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1
De, Kock Willem Johan. "Numerical simulation of the plastics injection moulding process". Doctoral thesis, University of Cape Town, 1994. http://hdl.handle.net/11427/18307.
Testo completoAbstract (sommario):
The Hele-Shaw formulation is widely used for the simulation of the injection moulding process. The influence of the Hele-Shaw approximations is, however, unknown. A two-dimensional numerical model based on the Hele-Shaw formulation, and a model based on the Navier-Stokes equations without the Hele-Shaw approximations were developed. The solutions obtained with these two approaches were compared to investigate the influence of the Hele-Shaw approximations on the simulation of the injection moulding process. Weakly compressible, non-Newtonian flow of an amorphous polymer melt under non-isothermal conditions were simulated using constitutive equations generalized to non-Newtonian materials. The finite volume method, which is a very powerful method yet easy to use, was used to discretize the governing equations as compared to finite element methods used in most other reported models. The influence of the Hele-Shaw approximations on the solutions of specific flow cases was determined by comparing the solutions obtained with the model based on the Hele-Shaw formulation and the model based on the Navier-Stokes equations. Parametric studies were done to compare the solutions of the two numerical models for a wider range of flow cases. The following conclusions were made as a consequence of this study: Numerical models to simulate the injection moulding process can be simplified and the computer time required to solve these models can be reduced by using the Hele-Shaw formulation instead of solving the full Navier-Stokes equations. Numerical models based on the Hele-Shaw formulation are well suited to simulate the injection moulding process when the geometries and flow conditions fall within certain limits. These limits are determined by the combined effect of the geometry and the flow conditions represented by the Reynolds number. The simplicity of the finite volume method used in the generalized Hele-Shaw model makes it an attractive model to use for injection moulding simulations.
2
Jüttner, Gabor, Tham Nguyen-Chung, Günter Mennig e Michael Gehde. "Simulation of the Filling Process in Micro-Injection Moulding". Universitätsbibliothek Chemnitz, 2008. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-200801189.
Testo completoAbstract (sommario):
Nowadays, the filling and solidification of macro-scale injection mouldings can be predicted using commercial CAE software. For micro-injection moulding, the conventional tools do not work for all process conditions. The reasons might be the lack of high quality database used in the simulation and the improperly specified boundary conditions which do not reflect the real state in the cavity. Special aspects like surface tension or "size dependent" viscosity might also be responsible for the inaccuracy of the simulations.
In this paper, those aspects related to the boundary conditions were taken into consideration, especially the thermal contact behaviour and the melt compression in the barrel which affects not only the temperature of the melt due to the compression heating, but also reduces the actual volume rate in the cavity. It can be shown that the heat transfer coefficient between the melt and the mould wall has a significant influence on the simulation results. In combination with precise material data and considering the reduction of the volume rate due to the melt compression in the barrel, the heat transfer coefficient may be quantified by means of reverse engineering. In general, it decreases when either the cavity thickness or the injection speed increases. It is believed that a pressure dependent model for the heat transfer coefficient would be more suitable to describe the thermal contact behaviour in micro injection moulding. The melt compression in the barrel affects definitely the filling behaviour and subsequently the heat transfer in the cavity as well, which is especially true for micro parts of high aspect ratio.
3
Fu, Tingrui. "PP/clay nanocomposites : compounding and thin-wall injection moulding". Thesis, Loughborough University, 2017. https://dspace.lboro.ac.uk/2134/24655.
Testo completoAbstract (sommario):
This research investigates formulation, compounding and thin-wall injection moulding of Polypropylene/clay nanocomposites (PPCNs) prepared using conventional melt-state processes. An independent study on single screw extrusion dynamics using Design of Experiments (DoE) was performed first. Then the optimum formulation of PPCNs and compounding conditions were determined using this strategy. The outcomes from the DoE study were then applied to produce PPCN compounds for the subsequent study of thin-wall injection moulding, for which a novel four-cavity injection moulding system was designed using CAD software and a new moulding tool was constructed based upon this design. Subsequently, the effects of moulding conditions, nanoclay concentration and wall thickness on the injection moulded PPCN parts were investigated. Moreover, simulation of the injection moulding process was carried out to compare the predicted performance with that obtained in practice by measurement of real-time data using an in-cavity pressure sensor. For the selected materials, the optimum formulation is 4 wt% organoclay (DK4), 4 wt% compatibiliser (Polybond 3200, PPgMA) and 1.5 wt% co-intercalant (erucamide), as the maximum interlayer spacing of clay can be achieved in the selected experimental range. Furthermore, DoE investigations determined that a screw speed of 159 rpm and a feed rate of 5.4 kg/h are the optimum compounding conditions for the twin screw extruder used to obtain the highest tensile modulus and yield strength from the PPCN compounds. The optimised formulation of PPCNs and compounding conditions were adopted to manufacture PPCN materials for the study of thin-wall injection moulding. In the selected processing window, tensile modulus and yield strength increase significantly with decreasing injection speed, due to shear-induced orientation effects, exemplified by a significantly increased frozen layer thickness observed by optical microscopy (OM) and Moldflow® simulation. Furthermore, the TEM images indicate a strong orientation of clay particles in the flow direction, so the PPCN test pieces cut parallel to the flow direction have 36.4% higher tensile modulus and 13.6 % higher yield strength than those cut perpendicular to the flow direction, demonstrating the effects of shear induced orientation on the tensile properties of thin-wall injection moulded PPCN parts. In comparison to injection speed, mould temperature has very limited effects in the selected range investigated (25-55 °C), in this study. The changes in moulding conditions show no distinctive effects on PP crystallinity and intercalation behaviour of clay. Impact toughness of thin wall injection moulded PPCN parts is not significantly affected by either the changes in moulding conditions or clay concentration (1-5 %). The SEM images show no clear difference between the fracture surfaces of PPCN samples with different clay concentrations. TEM and XRD results suggest that higher intercalation but lower exfoliation is achieved in PPCN parts with higher clay content. The composites in the thin sections (at the end of flow) have 34 % higher tensile modulus and 11 % higher yield strength than in the thicker sections, although the thin sections show reduced d001 values. This is attributed to the significantly enhanced shear-induced particle/molecular orientation and more highly oriented frozen layer, according to TEM, OM and process simulation results. In terms of the reduced d001 values in the thin sections, it is proposed that the extreme shear conditions in the thin sections stretch the PP chains in the clay galleries to a much higher level, compaction of clay stacks occurs as less interspacing is needed to accommodate the stretched chains, but rapid cooling allows no time for the chains to relax and expand the galleries back. Overall, data obtained from both actual moulding and simulation indicate that injection speed is of utmost importance to the thin-wall injection moulding process, development of microstructure, and thus the resulting properties of the moulded PPCN parts, in the selected experimental ranges of this research.
4
Mullath, Aravind. "Process simulation and optimisation of thin wall injection moulded components". Thesis, Loughborough University, 2013. https://dspace.lboro.ac.uk/2134/13521.
Testo completoAbstract (sommario):
Integrally moulded hinges and tension bands are important features in packaging components for plastic closures and their function is critically dependent on the flow induced micromorphology in the hinge section. Polymer characteristics and processing of the hinge also have an influence on the hinge properties obtained. This study is aimed at obtaining interrelationships between polymer characteristics, in-cavity flow, microstructure development and hinge properties, to produce hinges with enhanced functional properties. Three different virgin polypropylene (PP) grades were investigated (homopolymer PP-H, random copolymer PP-RC and impact copolymer PP-IC) and injection moulding simulation was carried out using Moldflow software. In-cavity data acquisition has been carried out for different sets of injection moulding conditions, using high performance transducers and a data acquisition system. A comparison between Moldflow simulation and practical injection moulding data suggests that, for thin wall injection moulded components the real time pressure data are in close agreement during the injection stage. During the packing stage there is some disagreement between these data, since the thickness of hinge and tension band sections are 0.4 mm and 0.5 mm respectively, suggesting that these dimensions are extending the capability of the software. An extensive study using a design of experiments (DoE) approach was carried out on both practical and predictive data. Injection velocity and melt temperature were the most influential factors on the component mechanical properties. From the optical micrographs it is observed that PP-RC has a finer micro-structure compared to PP-H and PP-IC and some micrographs confirm Moldflow simulation results in which hesitation effects are evident, as the flow converges into the thin hinge and tension band sections. PP-clay nanocomposites (PP-CN) were prepared using a twin screw compounder. Transmission electron microscopy (TEM) has shown some evidence of dispersion and exfoliation of the clay particles in the PP matrix. However, X-ray diffraction (XRD) results show a reduction in inter-layer spacing of PPCN s possibly due to clay compaction. The addition of nano-clay however has not resulted in any significant improvements in the mechanical properties of hinges and tension bands. The high degree of molecular orientation induced in the hinge and tension-band sections appears to mask any improvements attributed to the addition of nano-clay. From the reprocessed and post consumer recyclate (PCR) study conducted on hinges and tension bands, it is seen that with an increase in both the re-processing and PCR content there is a decrease in the component strength of around 14%, giving scope to potentially use PCR in future packaging applications. Investigations conducted on colour pigments (violet and green) reveal that the onset of crystallisation for green pigmented mouldings is considerably higher (16°C) than for natural and violet mouldings. Optical micrographs also reveal a finer microstructural texture for green components, indicating a high nucleating capability of the green pigment. Irrespective of the colour, both for hinges and tension bands, the yield stress values were around twice as high as the values quoted in the manufacturer s data sheet for isotropic PP, due to the high levels of molecular orientation in the hinge and tension band sections. In order to industrially validate the findings from the DoE study, commercial closures were produced in industry on a production tool then characterised. In the case of tension bands, there was a good agreement between the results obtained from lab scale and industrial study due to the relatively simple geometry. For hinges this agreement is not so clear. Finally a comparison of mechanical properties of the 3 PP grades shows that PP-H has a higher yield stress compared to PP-IC and PP-RC and yield stress is significantly higher (yield strain values are lower) than values quoted by the manufacturer. The PhD study has confirmed the process conditions that are able to optimise all the interactive effects to improve functional properties in high volume parts in the packaging industry.
5
Polynkin, A., L. Bai, J. F. T. Pittman, J. Sienz, Leigh Mulvaney-Johnson, Elaine C. Brown, A. Dawson et al. "Water assisted injection moulding: development of insights and predictive capabilities through experiments on instrumented process in parallel with computer simulations". Maney Publishing, 2008. http://hdl.handle.net/10454/3511.
Testo completoAbstract (sommario):
YesAn idealised model of core-out in water assisted injection moulding (WAIM) is set up to isolate the effect of cooling by the water on the deposited layer thickness. Based on simulations, this is investigated for a specific case as a function of Pearson number and power law index. It is found that cooling significantly reduces the layer thickness to the extent that a change in the flow regime ahead of the bubble, from bypass to recirculating flow, is possible. For shear thinning melts with high temperature coefficient of viscosity, the simulations show very low layer thickness, which may indicate unfavourable conditions for WAIM. Although in the real moulding situation, other effects will be superimposed on those found here, the results provide new insights into the fundamentals of WAIM. Investigation of other effects characterised by Fourier and Reynolds numbers will be reported subsequently. Some early process measurement results from an experimental WAIM mould are presented. Reductions in residual wall thickness are observed as the water injection set pressure is increased and the duration of water bubble penetration through the melt is determined experimentally. The formation of voids within the residual wall is noted and observed to reduce in severity with increasing water injection pressure. The presence of such voids can be detected by the signature from an infrared temperatures sensor.
6
Mulvaney-Johnson, Leigh. "Gas assisted injection moulding : experiment and simulation : industrial machine experimental studies of the effect of process variables on gas bubble formation, and with simulation based upon a pseudo-concentration method". Thesis, University of Bradford, 2001. http://hdl.handle.net/10454/4983.
Testo completoAbstract (sommario):
The gas assisted injection moulding process is an important extension to conventional injection moulding. Gas assist can be applied in a number of ways, but here the penetration of a gas bubble through the polymer melt is of interest. A 3D fi nite element implementation of a pseudo concentration method is employed to simulate the primary penetration of the gas bubble. The wall thickness prediction is an important result since the extent of bubble penetration is sensitive to the remaining melt fraction. A number of methods for experimental measurement are developed to measure characteristics of the gas assisted injection moulding process dynamics and product. Key process variables, on an industrial gas-assist machine, were measured and analysed, leading to an empirical model for wall thickness prediction. Gas delay time and injection velocity are shown to be most influential in controlling residual wall thickness. Simulation results are evaluated against the empirical model. The trends observed, for simulation and experiment, in wall thickness after changes in process variable settings are found to agree qualitatively. The wall thickness prediction is found to be within 10% of the experimentally obtained measurements.
7
Choi, Mun Ying. "Computer simulation of injection moulding of thermoplastics". Thesis, Imperial College London, 1985. http://hdl.handle.net/10044/1/37662.
Testo completo
8
Scholz, Steffen Gerhard. "Micro injection moulding : process monitoring and optimisation". Thesis, Cardiff University, 2011. http://orca.cf.ac.uk/14054/.
Testo completoAbstract (sommario):
The advances in micro engineering and especially micro products and micro components with functional micro and nano structures / features are directly dependent on the advances in manufacturing technologies for their scale up production. Micro injection moulding is one of the key technologies for cost affective serial production of micro components. In this thesis, the process capabilities and constraints of this technology were studied systematically. More specifically, new tool making process chains and various process factors affecting the micro injection moulding process were investigated. The manufacturing capabilities of this technology were further analysed by investigating the filling behaviour of micro cavities, the influence of air in micro cavities and the forces occurring during the demoulding stage. Chapter 2 of this thesis reviews the slate of the art in micro tooling and micro injection moulding. In Chapter 3 an advanced condition monitoring system was developed to better understand the behaviour of the injection moulding process. In particular, cavity pressure sensors were utilised to analyse interdependences between process conditions and key characteristics of cavity pressure curves. Chapter 4 investigates the influence and effects of air inside micro cavities. A design of experiments’ study was carried out to identify process settings for achieving an optimum filling of micro cavities In particular the flow length inside the cavity was investigated to judge about the process performance. Next, the demoulding stage of the injection moulding cycle was studied in Chapter 5. In particular, ejection forces were analysed to investigate the influence of different process settings on demoulding behaviour of polymer parts. This is especially important in order to avoid any part damage during demoulding. In Chapter 6 micro stereolithography was used to fabricate mould inserts for micro injection moulding. Experiments were carried out with such mould inserts, and the tool life in relation to process settings for both the manufacture of the inserts and their replication performance, was studied systematically. Finally, Chapter 7 summarises the main conclusions and contributions to knowledge of this research. Also, future research directions in the area of micro injection moulding are proposed and briefly discussed The main findings of this research can be summarised as follows: • Indirect measurement methods can be utilised to monitor cavity pressure conditions in micro injection moulding and it was shown that Pmax, Pwork and Prate were dependent on the materials and processing conditions. • The performance of the u-IM process can be improved by understanding the effects of V1 and air evacuation on Qmax, Q, and the part flow length. High u-IM process settings and a limited venting through the primary split line have a significant impact on the filling performance. The u-IM process performance can be improved by incorporating secondary vents and by applying vacuum methods for air evacuation. • Pmax, Pwork and Fe max were dependent on the processing conditions and there is a direct correlation between cavity pressure and demoulding force. The position of the pressure sensors is important, but the readings of both sensors correlate. The holding pressure has the highest impact on the maximum demoulding forces. Rapid tooling can be applied successfully in u-IM and offers a faster, cheaper and highly flexible manufacturing route for producing prototypes in the final material. Only the uSL inserts produced with a layer thickness of 20 um (less undercuts) survived during the demoulding stage. The best results were achieved with PP, followed by PC. ABS polymer parts couldn’t be replicated successfully.
9
Griffiths, Christian Andrew. "Micro injection moulding : tooling and process factors". Thesis, Cardiff University, 2008. http://orca.cf.ac.uk/54854/.
Testo completoAbstract (sommario):
The development of new micro devices is highly dependent on manufacturing systems that can reliably and economically produce micro components in large quantities. Micro injection moulding is one of the key technologies for micro-manufacture and is considered as a cost effective replication method for mass production. The capabilities of this replication technology have to be studied systematically in order to determine the process constraints. The present work concerns the tooling and process factors that influence micro injection moulding. The requirements of this manufacturing process are identified, and a review of the current state of the art in the field, Chapter 2, is used to assess the potential of this technology. To analyse further the manufacturing capabilities of this technology against the requirements, an investigation of the pre-filling, filling and part removal stages of the process cycle is conducted. In particular, in Chapter 3 the pre-filling capabilities of multi cavity micro tools with the use of a runner system is explored. The filling performance of spiral-like micro cavities was studied as a function of runner size in combination with selected process factors. Then, in Chapter 4 the filling of micro mould cavities with controlled tool surface finishes is investigated. Factors affecting the flow behaviour are discussed and a special attention is paid to the interaction between the melt flow and the tool surface roughness. Using the same part design as that of the tool surface finish investigation, in Chapter 5 a Finite Element Analysis (FEA) is used to verify the effects of process parameters, particularly the factors affecting shear rate, pressure and temperature. The results of this investigation were then compared with those reported in the experimental study. Finally, in Chapter 6 the application of micro mould surface treatments is analysed. The effects of different surface treatments on the de-moulding of parts with micro features are investigated to identify the best processing conditions in regards to de-moulding behaviour. To validate the process effects for these three process stages micro injection moulding experimental set-ups were specially designed and implemented. These experiments apply various part designs, tool-making techniques, process factors, part inspection and condition monitoring techniques, and FEA. To further understand the importance of process characteristics at the micro scale, an in depth analysis of the experimental results for each of the selected investigations was carried out. Finally, in Chapter 7 the results from each of the investigations are summarised, and the main research findings identified, in particular the influence of runner size on the process performance, tool surface finish effects on the filling process, the accuracy and sensitivity of the proposed FEA model, and the effects of tool surface treatment on part de-moulding.
10
Somnuk, Peerawat. "Experimental study of simultaneous co-injection moulding process". Thesis, University of Warwick, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.308577.
Testo completo
11
Zhiltsova, Tatiana Vladimirovna. "Injection moulding process optimization for microstructured parts production". Doctoral thesis, Universidade de Aveiro, 2013. http://hdl.handle.net/10773/12059.
Testo completoAbstract (sommario):
Doutoramento em Engenharia MecâncicaAo longo das últimas décadas, a micromoldação (u-moldação) por injeção de termoplásticos ganhou um lugar de destaque no mercado de equipamentos eletrónicos e de uma ampla gama de componentes mecânicos. No entanto, quando o tamanho do componente diminui, os pressupostos geralmente aceites na moldação por injeção convencional deixam de ser válidos para descrever o comportamento reológico e termomecânico do polímero na microimpressão. Por isso, a compreensão do comportamento dinâmico do polímero à escala micro bem como da sua caraterização, análise e previsão das propriedades mecânicas exige uma investigação mais alargada. O objetivo principal deste programa doutoral passa por uma melhor compreensão do fenómeno físico intrínseco ao processo da μ-moldação por injeção. Para cumprir com o objetivo estabelecido, foi efetuado um estudo paramétrico do processo de μ-moldação por injeção, cujos resultados foram comparados com os resultados obtidos por simulação numérica. A caracterização dinâmica mecânica das μ-peças foi efetuada com o objetivo de recolher os dados necessários para a previsão do desempenho mecânico das mesmas, a longo prazo. Finalmente, depois da calibração do modelo matemático do polímero, foram realizadas análises estruturais com o intuito de prever o desempenho mecânico das μ-peças no longo prazo. Verificou-se que o desempenho mecânico das μ-peças pode ser significativamente afetado pelas tensões residuais de origem mecânica e térmica. Estas últimas, resultantes do processo de fabrico e das condições de processamento, por isso, devem ser consideradas na previsão do desempenho mecânico e do tempo de serviço das u-moldações.
Over the last decades, microinjection moulding (uIM) of thermoplastics has gained a pertinent place on the market of electronic equipment and a broad range of the mechanical aids. However, when size of components drop to the micro level, the assumptions of the conventional injection moulding cease to describe the complex rheological and thermo-mechanical behavior of the polymer in the microimpression. Therefore, understanding of the polymer flow dynamics at the micro scale as well as characterization, assessment and prediction of the final mechanical properties require a great deal of additional research. The prime objective of this doctoral thesis is to get an insight into the physical phenomena inherent to μIM process. In order to comply with the established objective, a number of parametrical studies of the μIM process were carried on an instrumented micromould and then their results were compared with the obtained numerical simulation results gathered from process modeling phenomena. Dynamical mechanical characterization of μ-moulded parts was performed in order to collect the data required for prediction of their long-term mechanical performance. Finally, after calibration of polymer material model, a long-term transient structural analysis was carried out. It was found out that the structural performance of microparts was significantly affected by the thermo-mechanical (residual) stresses. The latter is an inherent feature of the injection moulding processing, and therefore has to be accounted for the prediction of the u-moulded parts’ service life.
12
Yin, Kam Hoe. "Dynamic optimisation for energy efficiency of injection moulding process". Thesis, University of Nottingham, 2015. http://eprints.nottingham.ac.uk/28837/.
Testo completoAbstract (sommario):
Low carbon economy has emerged as an important task in China since the energy intensity and carbon intensity reduction targets were clearly prescribed in its recent Twelfth Five-Year Plan during 2011-2015. While the largest enterprises have undertaken initial initiative to reduce their energy consumption, small and medium-sized enterprises (SMEs) will need to share the responsibilities in meeting the nation’s targets. However, there is no established structure for helping SMEs to reduce their efficiency gap and hence the implementation of energy-saving measures in SMEs still remains patchy. Addressing this issue, this thesis seeks to understand the critical barriers faced by SMEs and aims to develop proprietary methodologies that can facilitate manufacturing SMEs to close their efficiency gap. Process parameters optimisation is perceived to be an effective “no-cost” strategy which can be conducted by SMEs to realise energy efficiency improvement. A unique design of experiment (DOE) introduced by Dorian Shainin offers a simplistic framework to study process optimisation, but its application is not widespread and being criticised over its working principles. In order to address the inherent limitations of the Shainin’s method, it was integrated with the multivariate statistical methods and the signal-response system in the empirical study. The nature of the research aim also requires a theoretical approach to evaluate the economic performance of the energy efficiency investment. Hence, a spreadsheet-based decision support system (file SERP.xlsm) was created via dynamic programming (DP) method. The main contributions of this thesis can be subdivided into empirical level and theoretical level. At the empirical level, a technically feasible yet economically viable approach called “multi-response dynamic Shainin DOE” was developed. An empirical study on the injection moulding process was presented to examine the validity of this novel integrated methodology. The emphasis has been on the integration of multivariate techniques and signal-response analysis. The former successfully identified the critical factors to energy consumption and moulded parts’ impact performance regardless of the great fluctuation in the impact response. The latter enables the end-user to achieve different performance output based on the particular intent. At the theoretical level, the “DP-based spreadsheet solution” provides a convenient platform to help the rationally-behaved decision makers evaluate the energy efficiency investments. A simple hypothetical case study on the injection moulding industry was illustrated how the decision-making process for equipment replacement can evolve over time. To sum up, both proprietary methodologies enhance the dynamicity in the optimisation process to support injection moulding industry in closing their efficiency gap. The study at the empirical level was limited by the absence of real industrial case study where it is important to justify the practicality of the proposed methodology. Regarding the theoretical level, the dataset for initial validation on the spreadsheet solution was not available. Finally, it is important to continue the future work on the research limitations in order to increase the cogency of the proprietary methodologies for common use in the industry.
13
Schiffers, Reinhard, Georg P. Holzinger e Gernot Huster. "Adaptive process control for stabilizing the production process in injection moulding machines". Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-200201.
Testo completoAbstract (sommario):
Plastic injection moulding machines are a positive example of the possibilities in terms of performance and energy efficiency of modern hydraulic drives technology. In addition to the performance and energy efficiency of the machines, the quality of the plastic mouldings and an easy to use machines control is the focus. To ensure a constant plastics part quality the set process parameters of the injection moulding machines are kept constant by appropriate closed loop control strategies today. Assuming a constant quality of the processed plastic raw material, this strategy is effective. If it comes to a qualitative variation in the processed plastics, which often leads to a change in viscosity of the plastics melt, keeping processing parameters constant will not lead to a constant quality of the moulded parts. The deviations in the plastics viscosity have such a great influence on the moulding process that the relevant process parameters have to be adjusted manually in many cases. Often the stroke of the reciprocating screw system has to be adapted to reach a constant filling volume of the cavity and therefore avoid burr formation or short shots. In this paper an approach for adaptive process control is introduced. This control loop is able to correct the set points of specific machines parameters online within the production cycle and therefore is able to avoid changes in the produced parts quality.
14
Fronimidis, Dimitris. "On-line monitoring and control of the injection moulding process". Thesis, University of Bath, 2007. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.436877.
Testo completo
15
Pina, Estany Jordi. "Micro and nanostructures replication via injection moulding". Doctoral thesis, Universitat Ramon Llull, 2018. http://hdl.handle.net/10803/663803.
Testo completoAbstract (sommario):
Des del descobriment del poliestirè i el PVC a principis del segle XX, els plàstics han revolucionat el nostre dia a dia. Les 250 milions de tones que es fabriquen cada any s'utilitzen en un ampli ventall d'aplicacions com l'embalatge, la construcció, el transport, la medicina, l'electrònica, etc.
D'una forma similar, es preveu que la nanotecnologia sigui una innovació disruptiva el segle XXI. Des que la nanotecnologia va néixer com a ciència als anys 80, han aparegut un ampli ventall d'aplicacions com els xips en laboratoris, les superfícies amb propietats d'autoneteja, les superfícies antimicrobianes, aplicacions òptiques, etc.
Actualment, la nanotecnologia està saltant des dels centres de recerca cap a la indústria. Per fer això, el plàstic sembla ser un material adequat gràcies al seu baix cost, la fàcil fabricació i les propietats interessants com l'alta resistència tot i el baix pes, la durabilitat, la resistència a la corrosió, la transparència, etc.
Aquesta tesi estudia en detall com l'injecció de plàstic es pot utilitzar per fabricar peces de plàstic amb àrees nanoestructurades. La dinàmica de fluids i la dinàmica molecular s'utilitzen per quantificar els paràmetres de procés i geomètrics que afecten la replicació. Des d'un punt de vista experimental i dins d'un marc de treball comú entre IQS (Universitat Ramon Llull), CSIC i Flubetech, s'injecta plàstic en motlles amb zones nanoestructurades i s'utilitza un microscopi de forces atòmiques per quantificar l'efecte en la replicació de la temperatura, el temps d'omplerta, la càrrega de polímer i la geometria de la nanocavitat. Per acabar, SEAT i l'IQS han unit esforços per desenvolupar una aplicació industrial centrada en la millora de l'homogeneïtat lumínica mitjançant el nanotexturitzat d'una superfície, s'ha obtingut d'aquesta manera un mètode més econòmic i eficient que els utilitzats actualment en l'il·luminació de fars i pilots.Desde el descubrimiento del poliestireno y el PVC a principios del siglo XX, los plásticos han revolucionado nuestro día a día. Las 250 millones de toneladas que se fabrican cada año se utilizan en un ámplio abanico de aplicaciones como los embalajes, la construcción, los transportes, la medicina, la electrónica, etc. De una forma parecida, se prevé que la llegada de la nanotecnología sea un cambio disruptivo del siglo XXI. Desde que la nanotecnología nació como ciencia en los años 80, han aparecido distintas aplicaciones en distintos sectores como los laboratorios en chips, las superfícies autolimpiantes, las superfícies antimicrobios, aplicaciones ópticas, etc. Actualmente, la nanotecnología está saltando desde los centros de investigación a la industria. Para conseguir este salto, el plástico parece ser un material adecuado debido a su bajo coste, fácil fabricación y propiedades interesantes como su alta resistencia aún y su bajo peso, la resistencia a la corrosión, la transparencia, etc. Esta tesis estudia en detalle como la inyección de plástico se puede usar para fabricar piezas de plástico con zonas nanoestructuradas. La dinámica de fluidos computacional y la dinámica molecular se utilizan para cuantificar los parámetros de proceso y geométricos que afectan a la replicación. Desde el punto de vista experimental y en un trabajo conjunto entre IQS (Universidad Ramon Llull), CSIC y Flubetech, se inyecta plástico en moldes con superfícies nanoestructuradas y se analiza con un microscopio de fuerzas atómica el efecto en la replicación de la temperatura, el tiempo de llenado, la carga de polímero y la geometría de la nanocavidad. Para acabar, SEAT y IQS han unido esfuerzos para desarrollar una aplicación industrial centrada en la mejora de la homogeneidad lumínica mediante el nanotexturizado de una superficie, obteniendo así un método más económico y más eficiente que los métodos usados actualmente en iluminación de faros o pilotos.
Since polystyrene and PVC were discovered at the beginning of the 20th century, plastics have revolutionized our daily lives. The 250 millions of tonnes that are manufactured each year are used in a wide field of applications like packaging, building and construction, transportation, medical, electronics, etc. In a similar way, nanotechnology is called to lead a disruptive change on the 21th century. Since nanotechnology emerged as a science in the 1980s, a wide field of applications has appeared in different areas like lab-on-chips devices, surfaces with self-cleaning capabilities, antimicrobial surfaces, optical applications, etc. Currently, nanotechnology is jumping from the research area to the mass production industry. To do so, plastic appears to be a suitable material for its low cost, easiness to manufacture and interesting properties like high strength-to-weight ratio, durability, corrosion resistance, transparency, etc. This thesis studies in detail how injection moulding manufacturing technique can be used for manufacturing plastic parts with micro and nanostructured areas. Computational Fluid Dynamics and Molecular Dynamics simulation methods are used to quantify the process and geometrical factors that effect the replication. From the experimental point of view, in a common work between IQS (Ramon Llull University), CSIC and Flubetech, plastic is injected in moulds with nanostructured areas and an Atomic Force Microscope is used for quantifying the effect of temperature, filling time, polymer charge and nanoscale geometries in the replication of nanocavities. Finally, SEAT and IQS joined efforts to develop an industrial application consisting into an improve of light homogeneity through the nanotexturising of a surface, obtaining a costs reduction and a better efficiency than the currently used methods for lighting headlamps and rear lights.
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Lekakou, Constantina. "Simulation of flow, reaction and heat transfer in reaction injection moulding". Thesis, Imperial College London, 1987. http://hdl.handle.net/10044/1/47048.
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Sombatsompop, Narongrit. "The characteristics fo flowing polymer melts in the injection moulding process". Thesis, University of Manchester, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.493734.
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Hopkinson, N. "Investigation into part injection and heat transfer in the direct AIM'T'M process". Thesis, De Montfort University, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.391647.
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Verhoyen, Olivier. "Crystallization of polyethylene terephthalate in injection moulding : experiments, modelling and numerical simulation". Université catholique de Louvain, 1997. http://edoc.bib.ucl.ac.be:81/ETD-db/collection/available/BelnUcetd-03032009-173159/.
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Armitage, Philip David. "Modelling, simulation and control of the reaction injection moulding of polymer blends". Thesis, University of Bradford, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.278814.
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Bon, Abdul Talib. "Process quality improvement on beltline moulding manufacturing". La Rochelle, 2008. http://www.theses.fr/2008LAROS239.
Testo completoAbstract (sommario):
Le monde industriel de fabrication d'aujourd'hui doit satisfaire la demande des utilisateurs finaux et l'un des facteurs déterminants est la demande des produits de haute précision. Plusieurs stratégies ont été employées par les fabricants pour réduire le nombre des défauts et prédire la précision des processus de fabrication. L'approche de l'amélioration de contrôle de qualité, implémentée dans cette étude, comprend la mise en place des paramètres et l'optimisation pour le processus de la moulure des ceintures de caisse afin de réduire la durée de la prise et le nombre des défauts. Nous avons développé de nouvelles techniques dans la sélection des paramètres et l'optimisation, dans lesquelles nous utilisons deux techniques statistiques qui sont notamment l'optimisation d'essaim de particules et l'algorithme génétique. Les techniques de prévisions ARIMA développées au cours de cette étude pourraient devenir un outil d'interprétation des données plus supérieur que la méthodologie traditionnelle existante. Les résultats de cette étude serviront d'évidences utiles dans l'applicabilité de l'implémentation de la méthodologie de la moulure des ceintures de caisses proposée aux fabricantsThe world of manufacturing industries is forced to meet the demand of the end users and one of the factors is highly quality demand from customer and highly precise products have determined by manufacturing systems. Many strategues from manufacturer already did how to reduce the number of defected and forecast the manufacturing process to more accurate. Process Quality Improvement approach was introduced and implemented in this study. Which is a parameter setting and optimization for beltline moulding process have developed and optimized to both shorten setting time and reduce number of detect procedures. We developed new techniques in parameter selection and optimization which is we apply a statistical techniques, Particle Swarm Optimization (PSO) and Genetic Algorithm (GA) approach in this study. The ARIMA forecasting techniques developed for this study can forecast, and can become superior to traditional methodology where interpretation is needed. The findings from the study will serve as a useful evidence and applicability of the proposed methodology to beltline moulding manufacturer for implementation
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Statham, Michael J. "Economic manufacture of freeze-cast ceramic substrate shapes for the spray-forming process". Thesis, University of Bath, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.285297.
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Dawson, A. J. "Process and production measurements for automatic inspection and control of injection moulding". Thesis, University of Bradford, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.535848.
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Yang, Ziqi. "Advanced batch process modelling, control and optimization for injection stretch blow moulding". Thesis, Queen's University Belfast, 2016. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.713464.
Testo completoAbstract (sommario):
The injection stretch blow Moulding (ISBM) process is widely used to manufacture PET bottles for the beverage and consumer goods industry. However, at present the ISBM process, including both the stretch blow moulding and reheating processes, are totally open-loop. The processes are complex and users often have to rely heavily on trial and error method to set up and control it. In this research, with the main purpose to displace this experience-based trial and error method in the ISBM process, the associated modelling and control methods are proposed.
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Salomeia, Y. M. "Improved understanding of injection stretch blow moulding through instrumentation, process monitoring and modelling". Thesis, Queen's University Belfast, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.517044.
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Dimitrov, D., e A. Moammer. "Investigation of the impact of conformal cooling on the performance of injection moulds for the packaging industry". Journal for New Generation Sciences, Vol 8, Issue 1: Central University of Technology, Free State, Bloemfontein, 2010. http://hdl.handle.net/11462/548.
Testo completoAbstract (sommario):
Published ArticleThis paper discusses the results obtained from studies on the performance of different cooling layouts. The conventional method of cooling makes use of straight-line cooling channels. This simple method of cooling does not possess the capability of uniformly cooling down the part produced. In contrast, conformal cooling is a technique that makes use of cooling channels in an injection moulding tool that closely follows the geometry of the part to be produced. The paper presents some experiences gained in a comparative case study of conventional cooling vs conformal cooling using simulation, followed by an experimental validation and statistical analysis of the results.
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Igreja, Rui Alexandre Aires da Trindade. "Numerical simulation of the filling and curing stages in reaction injection moulding, using CFX". Master's thesis, Universidade de Aveiro, 2007. http://hdl.handle.net/10773/2419.
Testo completoAbstract (sommario):
Mestrado em Engenharia MecânicaOs métodos habitualmente utilizados para a simulação de injecção em moldes envolvem um número considerável de simplificações, originando reduções significativas do esforço computacional mas, nalguns casos também limitações. Neste trabalho são efectuadas simulações de Reaction Injection Moulding (RIM) com o mínimo de simplificações, através da utilização do software de CFD multi-objectivos CFX, concebido para a simulação numérica de escoamentos e transferência de calor e massa. Verifica-se que o modelo homogéneo para escoamentos multifásicos do CFX, geralmente considerado o apropriado para a modelação de escoamentos de superfície livre em que as fases estão completamente estratificadas, é incapaz de modelar correctamente o processo de enchimento. Este problema é ultrapassado através da implementação do modelo não homogéneo juntamente com a condição de fronteira de escorregamento livre para o ar. A reacção de cura é implementada no código como uma equação de transporte para uma variável escalar adicional, com um termo fonte. São testados vários esquemas transitórios e advectivos, com vista ao reconhecimentos de quais os que produzem os resultados mais precisos. Finalmente, as equações de conservação de massa, quantidade de movimento, cura e energia são implementadas conjuntamente para simular os processos simultâneos de enchimento e cura presentes no processo RIM. Os resultados numéricos obtidos reproduzem com boa fidelidade outros resultados numéricos e experimentais disponíveis, sendo necessários no entanto tempos de computação consideravelmente longos para efectuar as simulações. ABSTRACT: Commonly used methods for injection moulding simulation involve considerable number of simplifications, leading to a significant reduction of the computational effort but, in some cases also to limitations. In this work, Reaction Injection Moulding (RIM) simulations are performed with minimum of simplifications, by using the general purpose CFD software package CFX, designed for numerical simulation of fluid flow and heat and mass transfer. The CFX’s homogeneous multiphase flow model, which is generally considered to be the appropriate choice for modelling free surface flows where the phases are completely stratified and the interface is well defined, is shown to be unable to model the filling process correctly. This problem is overcome through the implementation of the inhomogeneous model in combination with the free-slip boundary condition for the air phase. The cure reaction is implemented in the code as a transport equation for an additional scalar variable, with a source term. Various transient and advection schemes are tested to determine which ones produce the most accurate results. Finally, the mass conservation, momentum, cure and energy equations are implemented all together to simulate the simultaneous filling and curing processes present in the RIM process. The obtained numerical results show a good global accuracy when compared with other available numerical and experimental results, though considerably long computation times are required to perform the simulations.
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Alenezi, Dharay Falah Saleh. "Process Parameters Optimisation of Injection Moulding using SLA Inserts in Conventional & CCC Moulds". Thesis, University of Portsmouth, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.523624.
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Al-Ashaab, Ahmed H. S. "A manufacturing model to capture injection moulding process capabilities to support design for manufacture". Thesis, Loughborough University, 1994. https://dspace.lboro.ac.uk/2134/10338.
Testo completoAbstract (sommario):
The achievement of "better, faster, cheaper" product designs is heavily dependent on providing appropriate information to design teams. One of the essential parts of the information is the manufacturing process information. The aim of this research has been to explore the representation of the capability of the injection moulding process in a software form. The resulting model termed a Manufacturing Model must provide a common source of information to a range of interacting Design for Manufacture applications. These applications in turn would produce feedback advice as the design evolves, to the users in order to assist in their design decisions. The manufacturing information to support injection moulding process has been categorized as mouldability features, mould elements and injection mould machine elements which represent the main entities of the Manufacturing Model. The EXPRESS language and EXPRESS-G have been used to provide a formal non-software dependent representation of the underlying structure of the Manufacturing Model. To explore the use of the Manufacturing Model information to support Design for Manufacturing (DFM) applications the Object-Oriented methodology of Booch has been used. Three DFM applications have been considered, these being Desigu for Mouldability, Supporting Mould Design and the Selection of Injection Machine. An experimental Manufacturing Model, based on the EXPRESS representation, and related DFM applications have been implemented in Object-Oriented form using LOOPS (Xerox 1988). This has been used to show that the capability of the injection moulding process has been captured in the Manufacturing Model and provides support to a range of interacting Design for Manufacture applications. While the EXPRESS language has provided a good tool to capture the structure of the Manufacturing Model, further work has been required to define the functional interactions between entities within the model. Using the object oriented paradigm to implement the Manufacturing Model has been demonstrated. The Booch methodology in addition to EXPRESS has provided the basis to model the functional interaction between the Manufacturing Model entities. As an implementation tool, LOOPS has proven to provide adequate object oriented capability. However there is requirement for software tools which can readily be integrated with other software tools. The research has provided a contribution to a structured, and extensible, approach which should influence future CAB system structures aiming to provide support to Concurrent Engineering.
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Nixon, James. "Analysis of the stretch blow moulding process and subsequent simulation development". Thesis, Queen's University Belfast, 2015. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.677457.
Testo completoAbstract (sommario):
Injection stretch blow moulding (ISBM) is the most common processing method of producing thin-walled poly (ethylene) terephthalate (PET) containers. With numerous processing parameters and complex deformation, there is still a certain amount of expert knowledge required to successfully convert a PET preform into a useable bottle, capable of passing rigorous post-process testing. The purpose of this work is to develop an accurate simulation of the bottle forming procedure through extensive examination of the input parameters and how they affect the preform deformation and bottle characteristics. By removing the bottle mould, a free-stretch-blow analysis was performed over a large process window. This procedure utilised the digital image correlation (DIC) method with a patterned preform heated using an oil bath. A corresponding simulation was constructed using ABAQUS/Explicit FE solver and a constitutive viscoelastic user material subroutine. A comparison between the experimental and predicted values of internal cavity pressure, stretch-rod force and surface strain was performed resulting in reduced accuracy at low flow rate, sequential-type deformations. Free-stretch-blow trials also highlighted the need for adequate preform storage as increased moisture content affects the deformation behaviour. Reapplying the bottle mould and using the same process parameters revealed that the simulation had difficulties in predicted accurate bottle thickness, particularly at higher flow rate. An insufficient contact friction model was concluded and more insight into the heat transfer and back pressure between the polymer and mould was required. Results from the simulation also demonstrated that the previously assumed incompressible behaviour of PET during bottle formation is incorrect. A novel method of measuring strain levels in all three directions was devised to reveal that deformation mode greatly affects the value of Poisson's ratio. Insight into the ISBM process and development of the simulation has been advanced through this work and key areas of further improvement have been revealed.
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Rawson, Keith William. "Shear controlled orientation effects with injection mouldings produced by the SCORIM process". Thesis, Brunel University, 1997. http://bura.brunel.ac.uk/handle/2438/6380.
Testo completoAbstract (sommario):
Injection moulding using the process of Shear Controlled Orientation Injection Moulding (SCORIM) to enhance the aesthetic characteristics of plastics was investigated. Unsightly surface weld lines were successfully removed from highly reflective aluminium flake pigmented plastics by the application of a single macroscopic SCORIM shear when used in series with Bright Surface Moulding (BSM). A gonio spectrophotometer (GSP) was used for the quantitative characterisation of the Al flake pigmented mouldings as a measure of surface reflectivity and preferred angle of reflection. The different directional properties of surface reflectivities to either side of a conventional weld line are unacceptable, but were successfully reoriented approximately uniformly with the use of SCORIM and BSM moulding (i. e. SBM) used in series. SBM therefore provided an acceptable quality of surface finish for mouldings originally containing a weld line, without deterioration of mechanical properties. Indeed, some improvements in mechanical properties were observed. Translucent two-colour mouldings were used to successfully demonstrate the flow paths taken by sheared material during the application of macroscopic shears. The use of intermittent shearing to encapsulate shear oriented material in the solidifying layers, manifested original and profound aesthetic effects. This resulted from mixing the two colours and was reproducible and widely variable. The morphology of isotactic polypropylene (iPP) processed in this way and examined by light and electron microscopy revealed how only one or two intermittent shears were required to orient a large volume of the moulding in the shear direction. Moreover, U-shaped flow paths demonstrated that the easiest shear route was close to the mouldings edges, an observation supported by x-ray analysis. The addition of Al flake pigment was found to act as a heterogeneous nucleant for ß-spherulites. This acted as a suitable marker for the clear identification of the displaced weld interface using polarised light microscopy, of filled and unfilled iPP. y-phase was identified with the use of only one or two intermittent shears which reflects an increase in molecular alignment and consequent improved mechanical properties. The intensity of the y-phase increased with the volume of material sheared. Strong evidence was also obtained of a linear relationship between the logarithm of the time lapse between two intermittent shears and the corresponding values of a-phase index, crystallinity index and percentage crystallinity. The values of each increasing proportionally with the length of time used. Microhardness characterisation revealed anisotropy within SCORIM samples consistent with preferred orientation and increased modulus in the shear direction. The skin layers were characterised as the softest region through the thickness of SCORIM mouldings. The results of this work were used to provide the basis of a computer simulation of the SCORIM process under development at the University of Wales Swansea.
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Mamen, Belgacem. "Experimental investigation and numerical simulation of thermal debinding and sintering processes in powder injection moulding". Thesis, Besançon, 2013. http://www.theses.fr/2013BESA2033/document.
Testo completoAbstract (sommario):
L'étape de déliantage est une étape importante et parfois critique pour le procédé Moulage par Injection des Poudres. A cet effet, des analyses thermogravimétriques (TGA) ont été réalisées pour bien comprendre les mécanismes du déliantage thermique sous atmosphère imposée (Argon). Les méthodes de Kissinger et Ozawa ont été utilisées, en se basant sur les résultats des analyses thermogravimétriques, afin d’estimer les paramètres cinétiques nécessaires pour la simulation numérique, notre modèle se propose de décrire les phénomènes physiques liés à la dégradation du polymère, le transfert de chaleur de la déformation du composant pendant le déliantage thermique.La deuxième partie de la thèse est dédiée à la compréhension des mécanismes et du comportement du fritage des composants en tungstène sous une atmosphère d’hydrogène jusqu’à une température de 1 700°C. Des appareils expérimentaux, ont été mis en place afin de constituer une base de données physiques nécessaire pour l’identification des différents paramètres. L’identification de l’ensemble des lois de comportement a été réalisée en prenant en compte les spécificités physiques des poudres utilisées. Un modèle de comportement de type thermo élasto-viscoplastique est formulé pour représenter la loi de densification par diffusion solide, puis appliqué pour les différentes tailles de poudres de tungstène. La dernière étape consiste à valider des simulations numériques avec ABAQUS pour une meilleure détermination des densités et des retraits finaux des composants injectésThermal debinding is one of the most important steps In Powder Injection Moulding process. Thermogravimetric analyses (TGA) are employed to analyze the physics and kinetics of thermal debinding behaviour under argon atmosphere. The Kissinger and Ozawa method have been used to estimate the kinetic parameters from thermogravimetric experiments. To set up the numerical simulations of thermal debinding stage using finite element method, a coupled mathematical has been developed. The basic steps of the proposed model consist to solve the following sequences of coupled problems: themal degradation of binder coupled with heat transfer and deformation phenomena by finite element method using Comsol Multiphysics software.In the second part of this thesis, sintering behaviour of tungsten powders injection moulded component, under pure hydrogen atmosphere at temperature up to 1700°C. The experimental tests are used to determine the material parameters in the parameters in the viscoplastic constitutive law, which is incorporated with the identified parameters in order to simulate the final shrinkages and densities of tungsten injection moulded components during the sintering process. Comparison between the numerical simulations results and experimental ones, in term of shrinkages and sintered densities, shows a good agreement
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Cheng, Zhi-Qiang. "On the development of a fully explicit vectorial algorithm for the 3D simulation of powder injection moulding". Besançon, 2006. http://www.theses.fr/2006BESA2010.
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Srivastava, Prashant. "Value stream mapping on foam injection moulding process-- the starting point of a six sigma project". Menomonie, WI : University of Wisconsin--Stout, 2005. http://www.uwstout.edu/lib/thesis/2005/2005srivastavap.pdf.
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Gruber, Juan-Mario. "Prozessführung beim Thermoplastspritzgießen auf Basis des Werkzeuginnendrucks : process control based in cavity pressure for the injection moulding process of thermoplastics /". Aachen : Mainz, 2005. http://bvbr.bib-bvb.de:8991/F?func=service&doc_library=BVB01&doc_number=014914373&line_number=0001&func_code=DB_RECORDS&service_type=MEDIA.
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Tran, Ngoc Tu. "Creating material properties for thermoset injection molding simulation process". Universitätsverlag Chemnitz, 2019. https://monarch.qucosa.de/id/qucosa%3A38380.
Testo completoAbstract (sommario):
Um den Spritzgießprozess zu simulieren, sind korrekte Materialdaten nötig. Diese Daten umfassen Viskositätsmodelle, Wärmekapazitätskoeffizienten, Wärmeleitfähigkeitskoeffizienten, PVT-Modelle und bei reaktiven Materialien Härtungsmodelle. Bei der Spritzgießsimulation von Thermoplasten sind die Materialdaten in der Regel in den Simulationstools verfügbar. Der Anwender kann problemlos Thermoplastmaterialdaten auswählen, die bereits in die Materialdatenbank der Simulationswerkzeuge eingebettet waren, um die gesamten Phasen des Thermoplastspritzgießprozesses zu simulieren. Bei der Duroplastspritzgießsimulation sind nur begrenzt Materialdaten vorhanden und selten aus der Datenbank der Simulationswerkzeuge verfügbar, da sie nicht nur bei der Messung rheologischer und thermischer Eigenschaften, sondern auch bei der Modellierung rheologischer und kinetischer mathematischer Modelle kompliziert sind. Daher ist es notwendig, eigene Materialdaten zu generieren. Um dieses Problem zu lösen, bedarf es einer umfangreichen Wissensbasis bei der Messung von Materialeigenschaften sowie der Erstellung eines Optimierungsalgorithmus´. Um den Prozess des duroplastischen Spritzgießens exakt zu simulieren, bedarf es zudem fundierter Kenntnisse über die Formfüllungseigenschaften dieser Materialien. Die Untersuchung des Fließverhaltens von duroplastischen Spritzgießmassen im Inneren der Kavität ist jedoch nicht ausreichend beschrieben. Bisher gab es noch keine veröffentlichten Hinweise, die zeigen, wie man aus experimentellen Messdaten (thermische und rheologische Daten) für den reaktiven Spritzgießsimulationsprozess komplette Materialdaten für Duroplaste erzeugen kann. Diese Probleme führen zu einer Abhängigkeit der Anwender von der Materialdatenbank der Simulationssoftware, was zu einer Einschränkung der Anwendung der Computersimulation in der duroplastischen Spritzgießsimulation und dem Vergleich zwischen experimentellen und Simulationsergebnissen führt. Darüber hinaus stellt sich die Frage, ob es beim Füllen der Kavität ein Wandgleiten zwischen Duroplastschmelze und Wandoberfläche gibt oder nicht. Aus diesem Grund wird die Wirkung des Wandgleitens auf die Kavitätenoberfläche bei der Simulation des duroplastischen Spritzgießens immer noch vernachlässigt. Die vorliegende Arbeit konzentriert sich auf drei wichtige wissenschaftliche Ziele. Das erste ist die Innovation eines neuen technischen Verfahrens zur physikalischen Erklärung des Formfüllverhaltens von duroplastischen Spritzgießmassen. Das zweite Hauptziel ist die Entwicklung einer numerischen Methode zur Erstellung eines duroplastischen Materialdatenblattes zur Simulation der Formfüllung von duroplastischen Spritzgießmassen. Schließlich wird die Erstellung von Simulationswerkzeugen auf der Grundlage der physikalischen Gegebenheiten und des erzeugten Materialdatenblattes durchgeführt.To simulate the injection molding process, it is necessary to set material data. The material data for an injection molding process must include a viscosity model and its fitted coefficients, heat capacity coefficients, thermal conductivity coefficients, a PVT model and its coefficients, a curing model and its coefficients (only for reactive injection molding). With thermoplastics injection molding simulation, the material data is generally available from simulation tools. Users could easily choose thermoplastics material data that was already embedded in the material data bank of simulation tools to simulate the entire phases of thermoplastics injection molding process. However, with thermosets injection molding simulation, the material data is found in limited sources and seldom available from data bank of simulation tools because of complication not only in rheological and thermal properties measurement but also in modeling rheological and cure kinetics mathematical models. Therefore, with thermoset injection molding compounds that its material data bank has not been found in data bank of simulation tools, before setting material data, it is necessary to create its own material data that simulation packages do not supply a tool. Therefore, to solve this problem, it requires an extensive knowledge base in measurements of material properties as well as optimization algorithm. In addition, to simulate exactly the thermosets injection molding compound process, it requires a profound knowledge in the mold filling characteristics of thermoset injection molding compounds. However, investigation of flow behavior of thermosets injection molding compounds inside the mold has not been adequately described. Up to now, there has not been any article that shows a complete way to create thermoset material data from measured experimental data (thermal data and rheological data) for the reactive injection molding simulation process. These problems are leading to the users ‘dependency on the material data bank of simulation tools, leading to restriction in application of computer simulation in the thermoset injection molding simulation and comparison between experimental and simulation results. Furthermore, there is still a big question related to whether there is or no slip phenomenon between thermosets melt and the wall surface during filling the cavity, for which has not yet been found an exact answer. Because of this the effect of wall slip on the cavity surface is still ignored during thermoset injection molding simulation process. This thesis focused on three key scientific goals. The first one is innovation of a new technical method to explain the mold filling behavior of thermoset injection molding compounds physically. The second key goal is developing numerical method to create thermoset material data sheet for simulation of mold filling characterizations of thermoset injection molding compounds. Finally, creating a simulation tool base on the physical technique and generated material data sheet.
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Gülçür, Mert, J.-M. Romano, P. Penchev, Timothy D. Gough, Elaine C. Brown, S. Dimov e Benjamin R. Whiteside. "A cost-effective process chain for thermoplastic microneedle manufacture combining laser micro-machining and micro-injection moulding". Elsevier, 2021. http://hdl.handle.net/10454/18446.
Testo completoAbstract (sommario):
YesHigh-throughput manufacturing of transdermal microneedle arrays poses a significant challenge due to the high precision and number of features that need to be produced and the requirement of multi-step processing methods for achieving challenging micro-features. To address this challenge, we report a flexible and cost-effective process chain for transdermal microneedle array manufacture that includes mould production using laser machining and replication of thermoplastic microneedles via micro-injection moulding (micromoulding). The process chain also incorporates an in-line manufacturing data monitoring capability where the variability in the quality of microneedle arrays can be determined in a production run using captured data. Optical imaging and machine vision technologies are also implemented to create a quality inspection system that allows rapid evaluation of key quality indicators. The work presents the capability of laser machining as a cost-effective method for making microneedle moulds and micro-injection moulding of thermoplastic microneedle arrays as a highly-suitable manufacturing technique for large-scale production with low marginal cost.
This research work was undertaken in the context of MICRO-MAN project (“Process Fingerprint for Zero-defect Net-shapeMICROMANufacturing”, http://www.microman.mek.dtu.dk/).MICROMAN is a European Training Network supported byHorizon 2020, the EU Framework Programme for Research andInnovation (Project ID: 674801). This research has also receivedfunding and support from two other Horizon 2020 projects:HIMALAIA (Grant agreement No. 766871) and Laser4Fun (GA no.675063).
The full-text of this article will be released for public view at the end of the publisher embargo on 04 Feb 2022.
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Pereira, M. F. V. T., J. M. Benson, M. Williams e H. Chikwanda. "Component and die design principles and process parameters for the metal injection moulding of a Ti alloy". Journal for New Generation Sciences, Vol 8, Issue 2: Central University of Technology, Free State, Bloemfontein, 2010. http://hdl.handle.net/11462/562.
Testo completoAbstract (sommario):
Published ArticleMetal injection moulding (MIM) offers advantages for mass production of components over conventional production methods for parts with complex shapes and large production runs. The MIM process includes mixing a fine metallic powder with a polymeric binder to produce a homogeneous feedstock. This enables the production of metallic components in a similar manner to plastic injection moulding. After undergoing a process of binder removal the components undergo a conventional sintering cycle. As significant shrinkage occurs (as much as 30%) this must be considered when designing the die cavity. This paper describes the design and manufacture of a die to produce tensile specimens. Extensive injection moulding trials to produce acceptable tensile components were undertaken. The complexities and possible implications of the design of a mould on the process are discussed. The outcomes of this research will be used by the CSIR for further development and application of the MIM technology for manufacture of high value components, such as dental implants.
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Vahlund, C. Fredrik. "Fibre orientation, rheological behaviour and simulation of the compression moulding process for composite materials /". Luleå, 2001. http://epubl.luth.se/1402-1544/2001/25/index.html.
Testo completo
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Soyama, Juliano [Verfasser], e Florian [Akademischer Betreuer] Pyczak. "Development of creep resistant titanium aluminide alloys for the Metal Injection Moulding process / Juliano Soyama ; Betreuer: Florian Pyczak". Cottbus : BTU Cottbus - Senftenberg, 2014. http://d-nb.info/111428310X/34.
Testo completo
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Cheng, C.-C., Y. Ono, Benjamin R. Whiteside, Elaine C. Brown, C. K. Jen e Philip D. Coates. "Real-time diagnosis of micro powder injection molding using integrated ultrasonic sensors". Hanser, 2007. http://hdl.handle.net/10454/4068.
Testo completoAbstract (sommario):
noReal-time diagnostics of ceramic powder injection molding using a commercial micromolding machine was performed using ultrasound. Miniature ultrasonic sensors were integrated onto the mold insert. Melt front, solidification, temperature variation and part detachment of the feedstock inside the mold cavity were observed. It has been demonstrated that ultrasonic velocity in feedstock inside the mold cavity, the ultrasonic contact duration during which the part and mold are in contact, and holding pressure can be used to assist with optimization of injection and cooling parameters to minimize energy consumption and maximize process efficiency.Real-time diagnostics of ceramic powder injection molding using a commercial micromolding machine was performed using ultrasound. Miniature ultrasonic sensors were integrated onto the mold insert. Melt front, solidification, temperature variation and part detachment of the feedstock inside the mold cavity were observed. It has been demonstrated that ultrasonic velocity in feedstock inside the mold cavity, the ultrasonic contact duration during which the part and mold are in contact, and holding pressure can be used to assist with optimization of injection and cooling parameters to minimize energy consumption and maximize process efficiency.
42
Demirel, Bilal, e bilal demirel@student rmit edu au. "Optimisation of Petaloid Base Dimensions and Process Operating Conditions to Minimize Environmental Stress Cracking in Injection Stretch Blow Moulded PET Bottles". RMIT University. SAMME, 2009. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20090305.154433.
Testo completoAbstract (sommario):
ABSTRACT Injection stretch blow moulded PET bottles are the most widely used container type for carbonated soft drinks. PET offers excellent clarity, good mechanical and barrier properties, and ease of processing. Typically, these bottles have a petaloid-shaped base, which gives good stability to the bottle and it is the most appropriate one for beverage storage. However, the base is prone to environmentally induced stress cracking and this a major concern to bottle manufacturers. The object of this study is to explain the occurrence of stress cracking, and to prevent it by optimising both the geometry of the petaloid base and the processing parameters during bottle moulding. A finite element model of the petaloid shape is developed in CATIA V5 R14, and used to predict the von Mises stress in the bottle base for different combinations of three key dimensions of the base: foot length, valley width, and clearance. The combination of dimensions giving the minimum stress is found by a statistical analysis approach using an optimisation and design of experiments software package ECHIP-7. A bottle mould was manufactured according to the optimum base geometry and PET bottles are produced by injection stretch blow moulding (ISBM). In order to minimise the stresses at the bottom of the bottle, the ISBM process parameters were reviewed and the effects of both the stretch rod movement and the temperature profile of the preform were studied by means of the process simulation software package (Blow View version 8.2). Simulated values of the wall thickness, stress, crystallinity, molecular orientation and biaxial ratio in the bottle base were obtained. The process parameters, which result in low stress and uniform material in the bottle base, are regarded as optimum operating conditions. In the evaluation process of the optimum bottle base, bottles with standard (current) and optimized (new) base were produced under the same process conditions via a two-stage ISBM machine. In order to compare both the bottles, environmental stress crack resistance, top load strength, burst pressure strength, thermal stability test as well as crystallinity studies ¬¬¬via modulated differential scanning calorimetry (MDSC) and morphology studies via environmental scanning electron microscopy (ESEM) and optical microscopy were conducted. In this study carried out, the new PET bottle with the optimised base significantly decreased the environmental stress cracking occurrence in the bottom of the bottle. It is found that the bottle with optimised base is stronger than the bottle with standard base against environmental stress cracking. The resistance time against environmental stress cracking are increased by about % 90 under the same operating process conditions used for standard (current) bottles; and by % 170 under the optimised process conditions where the preform re-heating temperature is set to 105 oC.
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Kietzmann, Clinton van Lingen. "Numerical simulation of the plastics moulding process using a thin gap numerical model / Clinton van Lingen Kietzmann". Thesis, Potchefstroom University for Christian Higher Education, 1995. http://hdl.handle.net/10394/851.
Testo completoAbstract (sommario):
The injection moulding process is one of the most popular means of mass producing components to
very small tolerances. Before the advent of the affordable computer, the methods used in injection
mould design were empirical in nature. Computational fluid dynamics offers the mould designer a tool
to predict and verify the mouldability of a part before any metal is cut on the actual mould. This thesis
describes the development of a thin gap numerical model that can be used by mould designers. The
thin gap assumption enables the Navier-Stokes equations to be simplified by the Hele-Shaw
approximation enabling the flow variables to be solved more efficiently, without a significant loss of
accuracy. Finite element solutions of the thin gap model are well documented and are well suited to
solving problems with complex geometries but in general finite element methods require more
memory and are slower in execution than finite-difference and finite volume methods.
A personal computer based program utilising the finite volume method for solving the Hele-Shaw
flow problem is developed in this thesis, which simulates the filling stage of the plastics injection
moulding process. The basic model was first developed on a two dimensional constant thickness
Cartesian coordinate domain using a constant tiscosity. This Newtonian model was then extended
with the Volume-of-Fluid method to include the moving boundary or free front. A suitable material
model was chosen to predict the viscosities of various grades of plastic at different temperatures and
pressures. Once this model produced accurate results it was extended to include generalised
curvilinear coordinates in order to solve problems on complex three dimensional geometries. The
program is tested and verified extensively with numerical experiments and experimental data from
previous published work and excellent results are obtained.
The final product of this thesis is a computer program which simulates the moving boundary during
the filling stage of the injection moulding process. This work contributes to the development and
understanding of finite volume and finite-difference methods in the simulation of plastic injection
moulding.Thesis (MIng (Meganies))--PU vir CHO, 1995.
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RENHA, JULIA FROTA. "SIMULATION OF INJECTION PROCESS FOR VISCOELASTIC POLYMER SOLUTION IN A RESERVOIR SCALE". PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2015. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=27000@1.
Testo completoAbstract (sommario):
PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROCom o objetivo de aumentar a capacidade dos poços petrolíferos, métodos convencionais de recuperação são utilizados, os quais consistem na injeção de água ou gás para a manutenção da pressão do reservatório. A produção do óleo ocorre através do deslocamento do mesmo no espaço poroso, onde a água, fluido deslocante, é injetada para ocupar gradualmente o espaço do óleo, fluido deslocado. Devido aos efeitos capilares e às heterogeneidades do meio poroso, uma parcela de óleo residual acaba ficando retida no reservatório, apresentando baixo fator de recuperação de óleo devido a elevada viscosidade do óleo em relação à viscosidade do fluido injetado e altas tensões interfaciais entre os fluidos. A adição de polímeros à água garante um aumento na sua viscosidade, melhorando a razão de mobilidade água/óleo no meio poroso. Uniformizando a frente de avanço e melhorando a eficiência de varrido devido à melhora no deslocamento do óleo. O presente trabalho analisa o comportamento viscoelástico do polímero, isolando o efeito viscoso e elástico em função das taxas de cisalhamento e extensão, implementado em um modelo de simulação de injeção de polímeros na escala de reservatórios. O efeito das propriedades reológicas da solução polimérica mostram nos resultados de produção uma frente de avanço mais estável e consequentemente uma melhora na taxa de recuperação de óleo quando avaliou-se o comportamento puramente cisalhante. Entretanto uma melhora na taxa de recuperação e na estabilidade da frente de avanço para o comportamento puramente extensional só pode ser observado quando o número de capilaridade foi aumentado consideravelmente.
Aiming to increase the capacity of oil fields, conventional recovery methods are used. These methods consist in the injection of water or gas to maintain the reservoir pressure. The oil production typically takes place by displacing this oil in the porous media, where the displacing fluid (water) is injected to gradually occupy the space of the displaced fluid (oil). Since due to capillary effects and the heterogeneity of the porous media, a residual oil portion ends up trapped in the reservoir. These methods lead to low values of oil recovery factor, which occurs mainly by two factors: high viscosity of the reservoir s oil in relation to the viscosity of the injected fluid and high interfacial tension between the fluids. The addition of polymers to the water ensures an increase in the viscosity of the injected fluid, improving mobility ratio between water and oil in the porous media. Thus, standardizing forward swept and improving the swept efficiency due to improved oil displacement, which reduces the formation of preferential paths in the reservoir, usually called fingers. This paper analyzes the viscoelastic behavior of the polymer, by isolating the viscous and elastic effect in function of its extension and shear rates, implemented in a polymer injection simulation model in a reservoir scale. The effect of the rheological properties of the polymer solution show in the production results a more stable injection front and consequently an oil recovery rate improvement when evaluated as a purely shear behavior. However an improvement in the recovery rate and stability of the injection front for pure extensional behavior can only be observed when the capillary number is increased considerably.
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Gibson, Millan-John. "Fibre Length Distribution and Dispersion during the Injection Moulding Process: An experimental study evaluating fibre length attrition and dispersion during processing of long glass fibre reinforced polymer composites in injection moulding including an evaluation of long glass fibre measurement techniques". Thesis, University of Bradford, 2018. http://hdl.handle.net/10454/17360.
Testo completoAbstract (sommario):
This project evaluates fibre length dispersion and distribution within the injection moulding process of long glass fibre reinforced polypropylene, sponsored by Autodesk Simulation.
The primary material used in this investigation was a 15 mm long glass fibre reinforced polypropylene consisting of two fibre content levels, 20 wt. % and 40 wt. %.
A review of previous research was compiled in this study to evaluate various glass fibre measurement methods and fibre breakage studies to establish where along the injection moulding process fibre breakage predominantly occurs and which process parameters have the greatest influence on fibre length distribution along the screw.
Based on literature findings, a manual fibre length measurement method was developed and applied in this study and benchmarked against existing commercially available automated software programs and found to be more accurate in obtaining a reliable fibre length distribution within a glass fibre reinforced sample.
Fibre length measurements from the nozzle confirmed that the majority of fibre breakage had already occurred in the screw. Measurements taken along the screw showed a drastic decrease in weighted average glass fibre length from initial pellet form to the end of the metering zone with sudden transitions to lower weighted average values seen at the beginning of the feeding zone and along the compression zone.
Fibre dispersion results from the nozzle and along the screw through the use of a μ-CT scanner showed a complex fibre flow and orientation of fibres with the preservation of fibre clusters being seen all along the injection moulding process but chiefly in the feeding and compression zones of the screw.
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Raza, Umar. "A service orientated architecture and wireless sensor network approach applied to the measurement and visualisation of a micro injection moulding process : design, development and testing of an ESB based micro injection moulding platform using Google Gadgets and business processes for the integration of disparate hardware systems on the factory shop floor". Thesis, University of Bradford, 2014. http://hdl.handle.net/10454/13362.
Testo completoAbstract (sommario):
Factory shop floors of the future will see a significant increase in interconnected devices for monitoring and control. However, if a Service Orientated Architecture (SOA) is implemented on all such devices then this will result in a large number of permutations of services and composite services. These services combined with other business level components can pose a huge challenge to manage as it is often difficult to keep an overview of all the devices, equipment and services. This thesis proposes an SOA based novel assimilation architecture for integrating disparate industrial hardware based processes and business processes of an enterprise in particular the plastics machinery environment. The key benefits of the proposed architecture are the reduction of complexity when integrating disparate hardware platforms; managing the associated services as well as allowing the Micro Injection Moulding (µIM) process to be monitored on the web through service and data integration. An Enterprise Service Bus (ESB) based middleware layer integrates the Wireless Sensor Network (WSN) based environmental and simulated machine process systems with frontend Google Gadgets (GGs) based web visualisation applications. A business process framework is proposed to manage and orchestrate the resulting services from the architecture. Results from the analysis of the WSN kits in terms of their usability and reliability showed that the Jennic WSN was easy to setup and had a reliable communication link in the polymer industrial environment with the PER being below 0.5%. The prototype Jennic WSN based µIM process monitoring system had limitations when monitoring high-resolution machine data, therefore a novel hybrid integration architecture was proposed. The assimilation architecture was implemented on a distributed server based test bed. Results from test scenarios showed that the architecture was highly scalable and could potentially allow a large number of disparate sensor based hardware systems and services to be hosted, managed, visualised and linked to form a cohesive business process.
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Menezes, Bezerra Renato [Verfasser], e F. [Akademischer Betreuer] Henning. "Modelling and Simulation of the Closed Injection Pultrusion Process / Renato Menezes Bezerra ; Betreuer: F. Henning". Karlsruhe : KIT-Bibliothek, 2018. http://d-nb.info/115122930X/34.
Testo completo
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Liu, Yao. "Heat transfer process between polymer and cavity wall during injection molding". Doctoral thesis, Universitätsbibliothek Chemnitz, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-157361.
Testo completoAbstract (sommario):
Injection molding is one of the most commonly applied processing methods for plastic components. Heat transfer coefficient (HTC), which describes the heat conducting ability of the interface between a polymer and cavity wall, significantly influences the temperature distribution of a polymer and mold during injection molding and thus affects the process and quality of plastic products. This thesis focuses on HTC under diverse processing situations. On the basis of the heat conducting principle, a theoretical model for calculating HTC was presented. Injection mold specially used for measuring and calculating HTC was designed and fabricated. Experimental injection studies under different processing conditions, especially different surface roughness, were performed for acquiring necessary temperature data. The heat quantity across the interface and HTC between a polymer and cavity wall was calculated on the basis of experimental results. The influence of surface roughness on HTC during injection molding was investigated for the first time. The factors influencing the HTC were analyzed on the basis of the factor weight during injection molding. Subsequently FEM (Finite element method) simulations were carried out with observed and preset value of HTC respectively and the relative crystallinity and part density were obtained. In the comparison between results from simulation and experiment, the result calculated with observed HTC shows better agreement with actually measured value, which can verify the reliability and precision of the injection molding simulation with observed HTC. The results of this thesis is beneficial for understanding the heat transfer process comprehensively, predicting temperature distribution, arranging cooling system, reducing cycle time and improving precision of numerical simulationDas Spritzgießen ist eines der am häufigsten angewandten Verarbeitungsverfahren zur Herstellung von Kunststoffkomponenten. Der Wärmedurchgangskoeffizient (WDK), welcher den Wärmeübergang zwischen Kunststoff und Werkzeugwand beschreibt, beeinflusst während des Spritzgießens maßgeblich die Temperaturverteilung im Bauteil und dem Werkzeug und folglich den Prozess und die Qualität der Kunststoffprodukte. Der Inhalt dieser Arbeit beschäftigt sich mit dem WDK unter verschiedenen Prozessbedingungen. Auf Grundlage des Wärmeleitungsprinzips wurde ein theoretisches Modell für die Berechnung des WDK vorgestellt. Es wurde dazu ein Spritzgießwerkzeug konstruiert und hergestellt, welches Messungen zur späteren Berechnung des WDK ermöglicht. Praktische Spritzgießversuche unter verschiedenen Prozessbedingungen, insbesondere unterschiedlicher Oberflächenrauheit, wurden für die Erfassung der erforderlichen Temperaturdaten durchgeführt. Auf Grundlage der experimentellen Ergebnisse wurde der Wärmeübergang zwischen dem Polymer und der Werkzeugwand berechnet. Der Einfluss der Oberflächenrauhigkeit auf den WDK wurde hierbei zum ersten Mal untersucht. Auf Grundlage des Bauteilgewichtes wurden anschließend die Faktoren, die den WDK beeinflussen, berechnet. Des Weiteren wurden FEM-Simulationen (Finite Element Methode) mit dem gemessenen und dem voreingestellten WDK durchgeführt und daraus der Kristallinitätsgrad und die Bauteildichte gewonnen. Der Vergleich zwischen den realen Ergebnissen und der Simulation zeigt, dass die Berechnungen mit dem gemessenen WDK eine bessere Übereinstimmung mit den realen Werten aufweist, was die Zuverlässigkeit und Präzision der Spritzgusssimulation bestätigt. Die Ergebnisse dieser Arbeit tragen zum umfassenden Verständnis des Wärmeübergangs im Spritzgießprozess, zur Vorhersage der Temperaturverteilung, zur Auslegung des Kühlsystems, zur Reduzierung der Zykluszeit und zur Verbesserung der Genauigkeit der numerischen Simulation bei
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Buriánková, Alena. "Analýza zmetkovitosti ve výrobním procesu". Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2019. http://www.nusl.cz/ntk/nusl-402585.
Testo completoAbstract (sommario):
The master’s thesis is focused on the reduction of rejection rate in production of plastic bowls with the use of statistic methods. The theoretical part of this thesis describes among others Statistical Process Control, Process capability and types regulatory diagrams. The basis for the practical part is data collection over a certain period of production, from which the percentage of the rejection rate is evaluated. Experiments and corrective actions are designed to improve the process and thereby reduce scrap.
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Elsheikhi, Salah A. "A holistic approach to injection moulding optimisation for product quality and cost through the characterisation of reprocessed polymeric materials and process monitoring : experimental evaluations and statistical analysis of multiple reprocessing of unfilled and short glass fibre filled polypropylene materials : an optimised methodology to realise minimum product cost at an acceptable product quality". Thesis, University of Bradford, 2011. http://hdl.handle.net/10454/5405.
Testo completoAbstract (sommario):
The plastics industry is one of the fastest growing major industries in the world. There is an increase in the amount of plastic used for all types of products due to its light weight and ability to reprocess. For this reason, the reprocessing of thermoplastics and the usability of reprocessed materials are gaining significance, and it is important to produce and consume plastic materials in an environmentally friendly way. In addition, rising raw material cost linked to the increased oil prices encouraged for reusing of the plastic materials. The aim of this research was to study and optimize the injection moulding process parameters to achieve a trade-off between the product cost and product quality, measured through mechanical properties and geometry, based on using regrind ratios. The work was underpinned by a comprehensive study of multiple reprocessing effects in order to evaluate the effect of process parameters, material behaviour, reprocessing effects and possible links between the processing parameters and key properties. Experimental investigations were carried out, in particular, focused on the melt preparation phase to identify key process parameters and settings. Multiple reprocessing stages were carried out; using two types of PP material: unfilled and short glass filled. A series of tests were used to examine product quality (mass, colour and shrinkage) and physical properties (density, crystallinity, thermal stability, fibre length, molecular weight, in-line and off-line viscosity, tensile strength, modulus of elasticity, elongation (%) and flexural strength). This investigation showed that the mouldability of the filled and unfilled PP materials, through the successive reprocessing stages (using 100 % regrind), was observed to be relatively consistent. Given the link between the processing parameters and key product and material properties, it is possible to manufacture products with minimal loss to part quality and mechanical properties. The final phase of the work focused on process optimisation study for short glass fibre filled PP material and the identified key process parameters (melt temperature, screw rotational speed, holding pressure, holding time and injection rate). A response surface experiment was planned and carried out for three reprocessing stages (0 %, 25 % and 50 % regrind). The fitted response surface models were utilised to carry out the trade-off analysis between the operating cost (material cost, energy cost and labour cost) and product quality (dimensions and tensile strength) Based on the optimal moulding conditions, the operating cost was reduced (from stage I as a reference), by 24% and 30 % for stage II and stage III respectively. A small, perhaps undetectable, change in product dimensions was noted. In addition, a small reduction in tensile strength was noted (from stage I as a reference), by 0.4% and 0.1 % for stage II and stage III respectively. The same data was applied in other countries (Australia, USA, Brazil, Libya and China) to manufacture the same product; and it was observed that the cost was reduced with increasing of regrind ratio. But the significant reduction of the cost, essentially, depended on those countries which have low wage rates (e.g. Brazil, Libya and China). For example, the cost of moulded product manufactured in China is £ 0.025 (using 50% of regrind), while the cost of the same product produced in Australia is £ 0.12, hence giving a total saving of 79 % and making it a valuable issue to be considered in industry.