Journal articles: 'Plaster molds'

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Shumkov, A. A., T. R. Ablyaz, and K. R. Muratov. "Assessing the Surface Distortion of Plaster Molds Made with the Use of SLA Models." Archives of Foundry Engineering 17, no. 3 (September 1, 2017): 123–26. http://dx.doi.org/10.1515/afe-2017-0103.

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Abstract The method of determining the accuracy of polymer molds in plaster forms has been discussed. Distortion of the surface of molds and plaster molds has been assessed. It has been found that the presence of monolithic and porous structure in the samples does not change the accuracy of the surfaces when forms are prepared for removing the material of the model. It has been found that in case of full-mold casting it is more expedient to form the mold cavity with cellular adjustable structures of molding prototypes.

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Tangboriboon, Nuchnapa, Sukritchai Teeraroengrit, Pattara Chawhuaymhak, Jirarat Kamonsawas, Sairung Changkhamchom, and Anuvat Sirivat. "Efficient stoneware hand mold for slip casting in natural rubber latex glove preparation." Progress in Rubber, Plastics and Recycling Technology 36, no. 4 (January 13, 2020): 262–83. http://dx.doi.org/10.1177/1477760619895013.

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Disposal medical gloves are an important product to maintain hygienic conditions, ensuring security for patients and safeguarding against infections. They are used in many fields, such as dental and medical, beauty and cuisine, food and pharmaceutical industries. Presently, aging populations and an emerging middle class in developing countries require medical gloves at a higher volume. Therefore, the demand for medical gloves increases continuously. In this work, two types of hand molds were prepared from stoneware clay and plaster to be used in the natural rubber glove preparation. The ceramic stoneware and plaster hand molds were prepared by the slip casting. The obtained stoneware hand molds were found to be superior to the commercial hand molds. Natural rubber latex (NRL) gloves were fabricated by dipping the stoneware hand mold coated with a coagulant into the NRL compound using the sulfur curing system at 120°C for 30 min. The latex solid:water weight ratio, drying and firing temperatures, and firing time used to prepare stoneware hand molds were found to affect the adsorption–adhesion properties between the mold surface and the NRL films. The obtained NRL films were further characterized for the physical properties such as appearance, film thickness, tackiness, and effusion of the phase formation by X-ray diffraction, the microstructure by scanning electron microscope, and the mechanical properties. The NRL glove films prepared by the stoneware hand mold possessed the high percentage elongation at break and the maximum load stress equal to 1343.30 ± 78.36% and 12.74 ± 2.34 MPa, respectively. On the other hand, the latex glove films prepared by the plaster hand mold with 80 consistency provided the percentage of elongation at break and the maximum load stress equal to 531.76 ± 2.54 and 21.01 ± 0.08 MPa, respectively.

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Parsley, Ronald L. "Latex casting of macroinvertebrate fossils." Paleontological Society Special Publications 4 (1989): 275–81. http://dx.doi.org/10.1017/s2475262200005244.

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Latex casting of macroinvertebrate fossils, when filling natural molds, produces a positive, or cast, reproduction of the organism. The use of latex molds to cast fossils in plaster or plastic materials will be discussed elsewhere in this volume. The purpose of this paper is to describe the preparation of latex casts for study and photography. The procedure for preparing a latex mold is essentially the same. Latex casts, carefully made, reproduce surficial detail with remarkable fidelity and a photograph of a whitened, stained-latex cast is often times indistingushable from a photograph of a well- preserved whitened body fossil.

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Jeong, M. J., Chang Hwan Seo, Yeong Hwan Song, K. J. Kang, and Bo Young Hur. "Effect of Different Upper Side Types of Plaster Molds on the Pore Formation of Al Foams via Upward Foaming Method." Materials Science Forum 569 (January 2008): 269–72. http://dx.doi.org/10.4028/www.scientific.net/msf.569.269.

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Fabrication of Aluminum foam with near net shape has been investigated by powder metallurgy method and conventional pouring method. PM method is good for fabrication of near net shape foam, but it needs high cost compared with pouring method. More cost-effective methods are needed to make near net shape al foam to be applied various field. Therefore, novel method for fabrication Al foam was researched in this paper. In order to prepare near shape Al foams with homogeneous pore structures, the so-called upward foaming method was designed and applied. By using this method, two kinds of molds were designed, one is stainless mold used for melting and foaming Al and another is the plaster mold with near net shape. The fabrication procedures of near net shape Al foam are as following: (1) a quantity of Al ingot was melted in the stainless mold; (2) Ca particles was added in the Al melt to increase its viscosity; (3) TiH2 was introduced in the thickened Al melt to make melt being foamed; (4) the plaster mold was put on the stainless steel one to make enlarging Al melt foam fill with the plaster one; (4) the plaster mold was removed and was cooled. In this study, in order to get near net Al foam with relative good pore structures, the plaster molds were designed with three different upside styles and their effects on the pore structures (pore size, porosity and cell wall thickness) of Al foams were investigated. The results showed that the Al foam had the relative good pore structures when the plaster mold with a void was applied.

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Pastirčák, R., A. Sládek, and E. Kucharčíková. "The Production of Plaster Molds with Patternless Process Technology." Archives of Foundry Engineering 15, no. 2 (June 1, 2015): 91–94. http://dx.doi.org/10.1515/afe-2015-0045.

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Abstract The work deals with technology Patternless process that combines 3 manufacturing process mold by using rapid prototyping technology, conventional sand formation and 3D milling. It's unconventional technology that has been developed to produce large-sized and heavyduty castings weighing up to several tons. It is used mainly in prototype and small batch production, because eliminating production of models. The work deals with the production of blocks for making molds of gypsum and gypsum drying process technology Thermomold. Into blocks, where were made cavities by milling were casted test castings from AlSi10MgMn alloy by gravity casting. At machining of the mold cavity was varied feed rate of tool of cemented carbide. Evaluated was the surface roughness of test castings, that was to 5 micrometers with feed from 900 to 1300 mm/min. The dimensional accuracy of castings was high at feed rate of 1000 and 1500 mm/min did not exceed 0.025 mm.

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Babcock, Loren E. "Casting with plaster of Paris." Paleontological Society Special Publications 4 (1989): 320–25. http://dx.doi.org/10.1017/s2475262200005281.

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Plaster of Paris is a general term for gypsum plasters and gypsum cements. Plaster, which has been in widespread use for producing casts of fossils since the Nineteenth Century (e.g., Green, 1832; Ward, 1866), is easily used for making rigid, long-lasting, and inexpensive casts of study specimens, and for making field casts from natural molds. Good general descriptions of the use of plaster are given in Clarke (1938) and Rich (1947), as well as in many recent books on sculpture (e.g., Miller, 1971; Chaney and Skee, 1973; Andrews, 1983), and in various brochures distributed by manufacturers (e.g., United States Gypsum Company, 1987a, 1987b). Using plaster for casting paleontological specimens was previously discussed in works by Quinn (1940), Keyes (1959), Heintz (1963), Rigby and Clark (1965), Rixon (1976), and Chase (1979).

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Church, Brent W., Daranee Tantbirojn, Thuydung Do, Martha H. Wells, and Antheunis Versluis. "Depth-of-cure of Bulk-fill Composites Cured in Tooth or Opaque Substrate." International Journal of Experimental Dental Science 6, no. 2 (2017): 68–73. http://dx.doi.org/10.5005/jp-journals-10029-1159.

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ABSTRACT Purpose To determine the effect of substrate on the depth-of-cure determination when using hardness profiles in a covered-slot technique and to introduce a new covered-slot method that uses tooth substrates. Materials and methods Three bulk-fill composites and one conventional composite were tested: Tetric EvoCeram Bulk Fill, Venus Bulk Fill, Filtek Bulk Fill Flowable, Filtek Supreme Ultra. The composites were light-cured in rectangular slots (2 mm deep, 2 mm wide) made in a plaster mold or an extracted tooth. The slots were covered with an orange glass plate during curing, leaving one end exposed for light-curing. After curing, the glass plate was removed and the sample was stored in the dark for 24 hours before Vickers hardness was measured as a function of depth at 0.5-mm intervals. Results were analyzed using two-way analysis of variance (ANOVA) and pairwise comparisons (significance level 0.05). Results The hardness of composites cured in covered-slot molds decreased with increasing depth (p < 0.001). Bulk-filled composites cured in plaster molds had a slightly lower depth-of-cure than those cured in natural tooth substrates. Differences between the tooth and plaster substrates were significant at all depths in the “packable” bulk-fill composite (Tetric EvoCeram Bulk Fill), and were significant at ≥2.5 and ≥3.5 mm in the flowable bulk-fill composites (Filtek Bulk Fill Flowable and Venus Bulk Fill) respectively. Conclusion Using natural tooth substrates in the covered-slot method increased the depth-of-cure of bulk-filled composites in comparison to opaque plaster molds. How to cite this article Church BW, Tantbirojn D, Do T, Wells MH, Versluis A. Depth-of-cure of Bulk-fill Composites Cured in Tooth or Opaque Substrate. Int J Experiment Dent Sci 2017;6(2):68-73.

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Gascoigne, H. E. "PLASTER AND WAX MOLDS FOR CASTING PHOTOELASTIC MODELS." Experimental Techniques 11, no. 10 (October 1987): 27–29. http://dx.doi.org/10.1111/j.1747-1567.1987.tb00624.x.

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Márquez, María José Manfredi, Priscila Távara Vidalón, Nuria Lara Hurtado, and Javier Ramos-Ortega. "Comparative Study Between the Different Techniques of Molding and the Morphology of the Foot in Weightbearing." Journal of the American Podiatric Medical Association 108, no. 5 (September 1, 2018): 375–82. http://dx.doi.org/10.7547/17-019.

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Background: Taking a mold of the foot is an important advance for podiatric medicine and an indispensable procedure for the individualization of orthopedic treatments. We sought to determine which method of measuring molds (plaster cast in weightbearing and nonweightbearing and phenolic foam in weightbearing) reproduces with more reliability the expansion of the foot in weightbearing by comparing the widths of the forefoot and hindfoot in the different methods and in barefoot weightbearing. Methods: In 54 patients, we studied the differences in width between the forefoot and hindfoot in barefoot weightbearing compared with in the different mold obtainment techniques. A descriptive, observational, and transversal study was performed in which foot molds were obtained with the different techniques, without corrective maneuvers, followed by scanning of each as well as barefoot weightbearing. Results: Significant differences among the techniques were shown, with phenolic foam being more similar to barefoot weightbearing in forefoot and hindfoot width. Conclusions: The method that reproduces the expansion of the foot in weightbearing with more reliability is phenolic foam. The forefoot width is superior in barefoot weightbearing versus the three foot casts studied. The hindfoot width is superior in the foot cast with plaster in weightbearing compared with barefoot weightbearing and the other two foot casts.

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Lazar, Liliana, and Ion Balasanian. "VALORIZATION OF PLASTER MOLDS WASTE FROM FINE CERAMIC INDUSTRY." Environmental Engineering and Management Journal 9, no. 1 (2009): 141–46. http://dx.doi.org/10.30638/eemj.2010.021.

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Ren, Jie, Xiang Chen, Yan-xiang Li, Yuan Liu, and Hua-wei Zhang. "Properties of fiber reinforced plaster molds for investment casting." China Foundry 17, no. 5 (September 2020): 332–40. http://dx.doi.org/10.1007/s41230-020-0056-9.

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Ochoa, Rafael E., Carlos A. Gutiérrez, Jorge López-Cuevas, Juan Rendón, José Luis Rodríguez-Galicia, and J. Cruz-Álvarez. "Effect of Water/Plaster Ratio on Preparing Molds for Slip Casting of Sanitaryware; Rheology of the Initial Plaster Slurry, Microstructure and Mold Properties." Transactions of the Indian Ceramic Society 77, no. 2 (April 3, 2018): 84–89. http://dx.doi.org/10.1080/0371750x.2018.1475262.

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Jahn, Josefine, Benjamin Thorenz, Markus Kafara, and Rolf Steinhilper. "Combining Optical Metrology and Additive Manufacturing for Efficient Manufacturing of Carbon Fiber Reinforced Plastic Orthopedics: A Case Study." Applied Mechanics and Materials 871 (October 2017): 275–83. http://dx.doi.org/10.4028/www.scientific.net/amm.871.275.

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Often, carbon fiber reinforced plastic (CFRP) manufacturing represents an expensive, time-consuming, small-scale production due to products and components characterized by complex geometric properties. In the field of orthopedic products individual molds, usually made of metal alloys or plaster, are necessary to shape the contour of the components. The presented case study focuses on individually manufactured masks for post-operative treatment of uncomplicated midfacial fractures that are frequent and typical injuries in popular contact sports like football or handball. To improve the costly process of CFRP production of individually manufactured masks, this paper describes the advantages of the combination of optical metrology (i.e. 3D-scanning) and additive manufacturing (i.e. 3D-printing). Therefore, the conventional process chain consisting of the main process steps molding (master pattern), casting (mold), CFRP laminating, curing, cutting and final assembly is replaced by 3D-scanning (instead of master pattern), followed by the revision of the CAD-model (to prevent cutting efforts), 3D-printing (mold), CFRP laminating, curing and final assembly. Summarizing, this case study on manufacturing of carbon fiber reinforced plastic orthopedics shows that the combination of innovative manufacturing technologies opens up new possibilities to increase efficiency in craft based manufacturing.

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Vancea, Cosmin, and Ioan Lazău. "Glass foam from window panes and bottle glass wastes." Open Chemistry 12, no. 7 (July 1, 2014): 804–11. http://dx.doi.org/10.2478/s11532-014-0510-x.

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AbstractGlass foams are building materials that now compete with classic insulating polymeric and fiber materials for thermal enveloping. The low flammability, high chemical durability and thermal stability are distinct advantages over polymeric materials. The present paper proposes the possibility of producing glass foam using two types of recycled glass wastes (window panes and bottle glass) together with plaster wastes from used ceramic casting molds as foaming agent. Optical microscopy, measurements of apparent porosity and density, hydrolytic and chemical stability, as well as thermal conductivity were used in order to characterize the obtained glass foams as insulator materials for the building industry. The apparent porosity of glass foams ranges between 20.19–54.54% when using window glass wastes, and 18.77–51.75% with bottle glass wastes. Thermal conductivity was less than 0.25 W mK-1 for all the studied glasses. The obtained results confirm that there exists an alternative method for producing glass foams, for example, from glass wastes and used ceramic plaster molds, which are utilized as foaming agents with good chemical stability and insulating properties.

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Gholami, M., and Z. Khakpour. "Manufacturing of new potential plaster molds for slip casting of alumina nanoparticles." Journal of the Australian Ceramic Society 55, no. 3 (October 26, 2018): 633–37. http://dx.doi.org/10.1007/s41779-018-0272-6.

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Auechalitanukul, Chiraporn, Ryan C. McCuiston, Benjawan Bunlangsup, Chanattha Naikorn, and Sudachuan Tapanaun. "Properties of Sintered Bronze-Graphite Containing Calcium Sulfate Derived from Waste Plaster Molds." Key Engineering Materials 751 (August 2017): 25–30. http://dx.doi.org/10.4028/www.scientific.net/kem.751.25.

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This study examined the effect of calcium sulfate additions on the microstructure and frictional properties of a 95bronze-5graphite material, commonly used for frictional applications. The samples were prepared using a powder metallurgy process. The calcium sulfate powder was obtained from recycled plaster molds previously used for ceramic slip casting. The plaster molds were cleaned, crushed and ball milled to obtain powder, which was calcined at 400 °C for 4 hours and screened. 2 to 8 weight percent calcium sulfate powder was added to a premixed powder composed of copper and tin and mixed before the graphite was added. The powder mixture was compacted into a disc shape under a pressure of 500 MPa. The compacted samples were sintered at 750 °C for 30 minutes in a reducing atmosphere. It was found that the green density of the samples decreased with increased amounts of calcium sulfate. After sintering, the densities were found to have decreased due to sample expansion. A finer microstructure was observed in the samples containing calcium sulfate powder, possibly due to a grain boundary pinning effect. The addition of calcium sulfate resulted in the reduction of both the measured friction coefficient and wear of the bronze-graphite samples. However, the addition of calcium sulfate powder above 6 weight percent appeared to show decreasing effects.

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Doctor, Michael, Anne Katz, Shannon O. McNamara, Jessica H. Leifer, Gabriela Bambrick-Santoyo, Turandot Saul, and Keith M. Rose. "A novel method for creating custom shaped ballistic gelatin trainers using plaster molds." Journal of Ultrasound 21, no. 1 (December 13, 2017): 61–64. http://dx.doi.org/10.1007/s40477-017-0274-1.

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Ochoa, Rafael E., Carlos A. Gutiérrez, Juan C. Rendón, and José L. Rodríguez. "Effect of preparation variables of plaster molds for slip casting of sanitary ware." Boletín de la Sociedad Española de Cerámica y Vidrio 56, no. 6 (November 2017): 263–72. http://dx.doi.org/10.1016/j.bsecv.2017.06.001.

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Lertcumfu, Narumon, Sukum Eitssayeam, Kamonpan Pengpat, Tawee Tunkasiri, Denis Russell Sweatman, Pharatree Jaita, and Gobwute Rujijanagul. "Influence of Curing on Calcined Kaolin-Based Geopolymer." Key Engineering Materials 690 (May 2016): 200–205. http://dx.doi.org/10.4028/www.scientific.net/kem.690.200.

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The object of this work was to use calcined kaolin-based geopolymer as an alternative material to replace ordinary Portland cement (OPCs) by applying geopolymerization processes. Geopolymer slurry was prepared from calcined kaolin and alkali activators, which consisted of 10 M NaOH and Na2SiO3 solution. The fresh slurry was cast into plastic molds and then cured at room temperature for 24 h. Reaction temperatures were measured (for 24 hours after casting). Compressive strength of the geopolymer was tested after curing at room temperature and after microwave heating. The mechanical properties increased with added plaster for microwave curing of 5 min. It is believed that this process can increase the efficiency of the production line for geopolymer.

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Anil, Umit Engin, Ebru Al, Kagan Kayaci, and Ferhat Kara. "Fabricating of Diatomite Based Ceramic Water Filter by a Novel Casting Method." Advances in Science and Technology 91 (October 2014): 48–53. http://dx.doi.org/10.4028/www.scientific.net/ast.91.48.

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In this study, a ceramic water filter with micron sized pores was developed based on diatomite raw material. The slip with diatomite earth which has tubular shaped particles was prepared by using agar. Agar is a gelatinous material derived from sea alges and used as a gelling agent in order to form ceramic filters by gel casting method. Rheology of the slip was investigated by rheometry. In the forming process, polymer and metal molds were used instead of plaster molds. After de-molding, ceramic filter samples were dried and fired at 1200 °C/ h for 2 hours. Density, phase analysis and microstructure properties of porous diatomite based filter material were measured and characterized by He picnometer, XRD and SEM, respectively. Water filtration performance and microbiological test results were also investigated.

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Aguilar-Castro, K. M., J. J. Flores-Prieto, M. E. Baltazar-Lopez, and E. V. Macias-Melo. "Design and experimental evaluation of a mixed-mode continuous solar dryer for plaster molds." Journal of Mechanical Science and Technology 26, no. 9 (September 2012): 2969–76. http://dx.doi.org/10.1007/s12206-012-0707-x.

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Siéssere, Selma, Mathias Vitti, Luiz Gustavo de Sousa, Marisa Semprini, and Simone Cecílio Hallak Regalo. "Educational material of dental anatomy applied to study the morphology of permanent teeth." Brazilian Dental Journal 15, no. 3 (December 2004): 238–47. http://dx.doi.org/10.1590/s0103-64402004000300014.

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The purpose of this report is to present educational material that would allow the dental student to learn to easily identify the morphologic characteristics of permanent teeth, and how they fit together (occlusion). In order to do this, macro models of permanent teeth with no attrition were carved in wax and later molded with alginate. These molds were filled with plaster, dental stone and/or cold-cured acrylic resin. The large individual dental stone tooth models were mounted on a wax base, thus obtaining maxillary and mandibular arches which were occluded. These dental arches were molded with plaster or dental stone. The authors suggest that these types of macro models allow an excellent visualization of the morphologic characteristics of permanent teeth and occlusion. Dental students are able to carve the permanent dentition in wax with great facility when they can observe macro models.

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León-Carriedo, M., Carlos A. Gutiérrez-Chavarría, and Jose Luis Rodríguez-Galicia. "Multilayered Zircon-Alumina Components Fabricated by Slip Casting." Materials Science Forum 755 (April 2013): 145–51. http://dx.doi.org/10.4028/www.scientific.net/msf.755.145.

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In recent years there have been many studies attempting to increase the mechanical properties and reliability of structural ceramic materials; the forming methods used for this purpose are based on multi-layered materials to induce residual stress between interface layers. In this work were made monolithic and multi-layered materials manufactured by casting in plaster of Paris molds using zircon and alumina as raw materials, mechanical and microstructure characterizations were compared, founding that, indeed, the laminar designs can substantially improve the mechanical properties of manufactured materials by the compressive stress between the interface layers.

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Meng, Xue Hua, Zu Quan Jin, Qing Li, and Ji Xiu Zhang. "Analysis for the Influence of the Admixture on the Solidification Rate of Expansion of the α-High-Strength Gypsum Plaster." Advanced Materials Research 446-449 (January 2012): 1153–57. http://dx.doi.org/10.4028/www.scientific.net/amr.446-449.1153.

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The α-type high-strength gypsum with its superior strength and performance is widely used in precision casting, ceramic molds, arts and crafts as well as plaster and GRG self-leveling and other industries that have higher demands to the dimensional stability of the products. Solidification rate of expansion is an important characterized parameters of gypsum volume stability, and also an important indicator of α-High-Strength gypsum plaster. The common adjustment method of Solidification rate of expansion is to add additives to change the gypsum hydration process. But the influences of different types of additives on setting expansion have not been studied yet, therefore, this paper studied on the influences of citric acid, tartaric acid and sodium pyrophosphate on the solidification rate of expansion of the α-High-Strength gypsum plaster. The results indicate that the gypsum expansion rate was decreased with the increase of gypsum set retarder, the expansion rate was firstly increased and then decreased when the citric acid and sodium pyrophosphate increased; however, when the tartaric acid increased, the expansion gradually decreased, and the tartaric acid and the expansion of the gypsum by and large are in an inverse proportion.

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Velazco, D. P. C., E. F. Sancet, F. Urbaneja, M. Piccico, M. F. Serra, M. F. Acebedo, G. Suárez, and N. M. Rendtorff. "Rapid prototyping of a complex model for the manufacture of plaster molds for slip casting ceramic." Cerâmica 60, no. 356 (December 2014): 465–70. http://dx.doi.org/10.1590/s0366-69132014000400003.

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Computer assisted designing (CAD) is well known for several decades and employed for ceramic manufacturing almost since the beginning, but usually employed in the first part of the projectual ideation processes, neither in the prototyping nor in the manufacturing stages. The rapid prototyping machines, also known as 3D printers, have the capacity to produce in a few hours real pieces using plastic materials of high resistance, with great precision and similarity with respect to the original, based on unprecedented digital models produced by means of modeling with specific design software or from the digitalization of existing parts using the so-called 3D scanners. The main objective of the work is to develop the methodology used in the entire process of building a part in ceramics from the interrelationship between traditional techniques and new technologies for the manufacture of prototypes. And to take advantage of the benefits that allow us this new reproduction technology. The experience was based on the generation of a complex piece, in digital format, which served as the model. A regular 15 cm icosahedron presented features complex enough not to advise the production of the model by means of the traditional techniques of ceramics (manual or mechanical). From this digital model, a plaster mold was made in the traditional way in order to slip cast clay based slurries, freely dried in air and fired and glazed in the traditional way. This experience has shown the working hypothesis and opens up the possibility of new lines of work to academic and technological levels that will be explored in the near future. This technology provides a wide range of options to address the formal aspect of a part to be performed for the field of design, architecture, industrial design, the traditional pottery, ceramic art, etc., which allow you to amplify the formal possibilities, save time and therefore costs when drafting the necessary and appropriate matrixes to each requirement.

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Cowden, K., B. Giammara, T. Devine, and J. Hanker. "Effects of sterilization modes on the mechanical strengths of plaster of paris implants." Proceedings, annual meeting, Electron Microscopy Society of America 47 (August 6, 1989): 890–91. http://dx.doi.org/10.1017/s0424820100156432.

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Plaster of Paris (calcium sulfate hemihydrate, CaSO4. ½ H2O) has been used as a biomedical implant material since 1892. One of the primary limiting factors of these implants is their mechanical properties. These materials have low compressive and tensile strengths when compared to normal bone. These are important limiting factors where large biomechanical forces exist. Previous work has suggested that sterilization techniques could affect the implant’s strength. A study of plaster of Paris implant mechanical and physical properties to find optimum sterilization techniques therefore, could lead to a significant increase in their application and promise for future use as hard tissue prosthetic materials.USG Medical Grade Calcium Sulfate Hemihydrate Types A, A-1 and B, were sterilized by dry heat and by gamma radiation. Types A and B were additionally sterilized with and without the setting agent potassium sulfate (K2SO4). The plaster mixtures were then moistened with a minimum amount of water and formed into disks (.339 in. diameter x .053 in. deep) in polyethylene molds with a microspatula. After drying, the disks were fractured with a Stokes Hardness Tester. The compressive strengths of the disks were obtained directly from the hardness tester. Values for the maximum tensile strengths σo were then calculated: where (P = applied compression, D = disk diameter, and t = disk thickness). Plaster disks (types A and B) that contained no setting agent showed a significant loss in strength with either dry heat or gamma radiation sterilization. Those that contained potassium sulfate (K2SO4) did not show a significant loss in strength with either sterilization technique. In all comparisons (with and without K2SO4 and with either dry heat or gamma radiation sterilization) the type B plaster had higher compressive and tensile strengths than that of the type A plaster. The type A-1 plaster however, which is specially modified for accelerated setting, was comparable to that of type B with K2SO4 in both compressive and tensile strength (Table 1).

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Hanker, J., K. Cowden, R. Noecker, P. Yates, N. Georgiade, and B. Giammara. "Effects of compression during formation on the microstructure of composite hydroxylapatite/plaster implants for bone reconstruction." Proceedings, annual meeting, Electron Microscopy Society of America 46 (1988): 750–51. http://dx.doi.org/10.1017/s0424820100105813.

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Composites of plaster of Paris (PP) and hydroxylapatite (HA) particles are being applied for the surgical reconstruction of craniofacial bone defects and for cosmetic surgery. Two types of HA particles are being employed, the dense sintered ceramic (DHA) and the porous, coralline hydroxylapatite (PHA) particles. Excess water is expressed out of the moistened HA/PP mixture prior to implantation and setting by pressing it in a non-tapered syringe against a glass plate. This results in implants with faster setting times and greater mechanical strengths. It was therefore of interest to compare samples of the compressed versus noncompressed mixtures to see whether or not any changes in their microstructure after setting could be related to these different properties.USG Medical Grade Calcium Sulfate Hemihydrate (which has the lowest mortar consistency of any known plaster) was mixed with an equal weight of Interpore 200 particles (a commercial form of PHA). After moistening with a minimum amount of water, disc-shaped noncompressed samples were made by filling small holes (0.339 in. diameter x 0.053 in. deep) in polypropylene molds with a microspatula.

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De Oliveira, Marciana Castanha, Thais Maira Borges, Flaviana Alves Dias, Paula Vanessa Pedron Oltramari-Navarro, Marcelo Lupion Poletic, and Thais Maria Freire Fernandes. "Dimensional Stability of Alginates Molds Tridimentionally Scanned." Journal of Health Sciences 20, no. 2 (July 27, 2018): 78. http://dx.doi.org/10.17921/2447-8938.2018v20n2p78-82.

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AbstractAlginate is among the most used materials in dentistry to create teeth negative printing and reproduction. The goal of this study was to compare dimensional changes of alginate scanned impression materials. Thirty impressions of a standard typodont were performed using three types of alginate (Hydrogum 5; Jeltrate Plus and Avagel). The impressions were scanned by the scanner 3Shape R700T and scans were performed immediately after molding. The analysis of digita models were performed at OrthoAnalyzer ™ 3D software. Measurements were carried out in relation to the transverse dimension (intercanine, interpremolares and intermolar). Method error was evaluated through the Intraclass Correlation Coefficient (ICC) and Bland-Altman. One-way ANOVA, Dunnet Post-test were used to compare the different groups in relation to Typodont (gold standard) for the different outcome variables. The data were tabulated in Statistical Package for Social Sciences version 20.0 and Minitab 17.0 softwares to compare groups. The significance level was 5%. The posterior transverse variables (D1PM, D2PM and DM) presented a statistically significant difference regarding the gold standard (Typodont) for the plaster models performed after the Avagel molding. In the digital models performed just after molding, only in DM, the Avagel material group presented values statistically higher than the control group. The alginates Hydrogum 5 and Jeltrate Plus presented dimensions closer to the gold standard.Keywords: Dental Impression Materials. Dental Models. Imaging, Three-Dimensional.ResumoO alginato está entre os materiais de moldagem mais utilizados na Odontologia para criar impressão e reprodução negativa dos dentes. O objetivo desse trabalho foi comparar alterações transversais de três marcas comerciais de alginato (Hydrogum, Jeltrate e Avagel) em moldes de alginatos. Trinta moldes de um Typodont padrão foram realizados, utilizando três tipos de alginato (Hydrogum 5; Jeltrate Plus e Avagel). Os moldes foram escaneados por meio do scanner 3Shape R700T e os escaneamentos realizados logo após a moldagem e logo após a obtenção dos modelos de gesso. As análises dos modelos digitais foram realizadas no software OrthoAnalyzer™ 3D. Foram realizadas mensurações em relação à discrepância transversal (inter-caninos, inter primeiro pré-molar, inter-segundo pré-molar e inter-molares). O erro do método foi avaliado por meio do Coeficiente de Correlação Intraclasse (CCI) e Bland-Altman. Utilizou-se Análise de Variância (one-way ANOVA, Pós-teste Dunnet) para comparação dos diferentes grupos em relação ao typodont (padrão-ouro) para as diferentes variáveis de desfecho. A análise estatística foi realizada nos programas Statistical Package for Social Sciences versão 20.0 e no programa Minitab 17.0 para comparação dos grupos. O nível de significância foi de 5%. As variáveis transversais posteriores (D1PM; D2PM e DM) apresentaram diferença estatisticamente significante em relação ao padrão-ouro (manequim) para os modelos de gesso realizados após a moldagem com Avagel. Nos modelos digitais realizados logo após a moldagem, apenas na DM, o grupo do material Avagel apresentou valores estatisticamente maiores do que o grupo controle. Os alginatos Hydrogum 5 e Jeltrate Plus apresentaram dimensões mais próximas do padrão-ouro.Palavras-chave: Materiais para Moldagem Odontológica. Modelos Dentários. Imagem Tridimensional.

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Pereira, Jefferson Ricardo, Janaina Salomon Ghizoni, Paulo Henrique Orlato Rossetti, Naudy Brodbeck May, and Accácio Lins do Valle. "Imperfections in plaster surfaces caused by the release of hydrogen gas of polyvinylsiloxane impression materials." Journal of Research in Dentistry 1, no. 2 (September 7, 2013): 98. http://dx.doi.org/10.19177/jrd.v1e2201398-106.

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Purpose: The purpose of this study was to evaluate the number of bubbles of hydrogen liberation from different polyvinylsiloxane impression materials. Material and Methods: A metallic stainless steel jig containing six receptacles, like trays, was constructed to accommodate the impression materials. The molds were poured immediately, and at 1 hour, 12 hours and 24 hours in order to evaluate the number of bubbles present in each sample. Each sample was made of improved stone (type IV), totaling 48 samples for each polyvinylsiloxane impression material. After setting, the surface of each sample was inspected under a light microscope at 40x magnification and the number of bubbles was recorded. Results were submitted to statistical analysis by ANOVA and Tukey Test (p=.05). Results: ANOVA test showed statistically significant differences among the polyvinylsiloxane impression materials, as determined by the number of bubbles (p<.05). The Tukey test showed statistically significant differences among the three groups (p<.05). Conclusions: Statistical differences were found between addition silicone with regard to the ideal time to wait for the plaster cast, showing that Aquasil results in fewer bubbles in plaster, followed by the President and Simply Perfect samples.

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Nascimento, Patrícia Lins Azevedo do, Rafael Bezerra Ribeiro, Cícero Romão Gadê-Neto, and Alexandre Henrique de Moura Dias. "Incorporation of disinfectants for obtaining dental stone: microbiological and dimensional evaluation." Revista de Odontologia da UNESP 44, no. 1 (February 2015): 24–30. http://dx.doi.org/10.1590/1807-2577.1036.

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AIM: To assess dimensional change and antimicrobial activity of disinfectants substances incorporated during the dental stone manipulation. MATERIAL AND METHOD: In vivo - microorganisms were collected in alginate molds of 30 volunteers inoculated on BHI agar and incubated at 37 °C for 24 hours. The molds were cast with type IV gypsum, manipulated with saline (G1), 1% sodium hypochlorite (G2) and 4% chlorhexidine (G3), replacing the water. After setting of plaster with 1 hour two collections on models were made. After 24 hours, the readings were performed. The Kruskal-Wallis and Wilcoxon tests with confidence interval of 99% and 95% respectively were used. In vitro - Müeller Hinton agar petri dishes were inoculated with S. mutans (ATCC25175), S. sanguis (ATCC10556) and E. faecalis (ATCC29212), over which were placed steel rings filled with the same substances of the in vivo study. After deposition of gypsum and incubation, halos were measured with a digital caliper and data were submitted to ANOVA and Tukey's test with confidence interval of 95%. Dimensional Change - With a metallic matrix and a perfectly adapted tray, the insertion axis and force used for moulding and obtain 30 specimens in type IV gypsum were standardized, following the same distribution of the study groups in vivo. The specimens were measured by Image Pro Plus software and data were submitted to ANOVA and Tukey's test with confidence interval of 95%. RESULT: Data from the in vivo study demonstrated a significant difference between the mold and each model (p<0.001). In the Wilcoxon test there was no significant difference between groups of models. At the in vitro test, G2 showed greater inhibition zones in all micro-organisms tested compared to G3, but with respect to dimensional changes, there was a significant difference between solutions and metallic standard, where G3 caused less change than G2. CONCLUSION: Chlorhexidine 4% showed to be the most suitable disinfectant.

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Halápi, Dávid, and László Varga. "Application of Additive Technology in Precision Casting." International Journal of Engineering and Management Sciences 5, no. 2 (April 15, 2020): 43–56. http://dx.doi.org/10.21791/ijems.2020.2.6.

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In this paper the surface of the prepared test specimens had been examined with light microscopy and surface roughness measurements. In order to improve the surface smoothness of PLA specimens, application of ethyl acetate was required. After this surface treatment, microscopic images were taken again. The melting and decomposition temperatures of the materials had been determined using derivatography. The chosen method was precision casting with gypsum molding. Also, the plaster molds had been burnt out according to the predefined melting and firing diagram. The measurement series shows that the samples produced by 3D printing can also be used in the field of precision casting. They provide greater freedom of design, more sophisticated pieces, and prototypes can be finished in a shorter amount of time.

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Zivcová, Zuzana, Eva Gregorová, and Willi Pabst. "Alumina ceramics prepared with new pore-forming agents." Processing and Application of Ceramics 2, no. 1 (2008): 1–8. http://dx.doi.org/10.2298/pac0801001z.

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Porous ceramics have a wide range of applications at all length scales, ranging from filtration membranes and catalyst supports to biomaterials (scaffolds for bone ingrowths) and thermally or acoustically insulating bulk materials or coating layers. Organic pore-forming agents (PFAs) of biological origin can be used to control porosity, pore size and pore shape. This work concerns the characterization and testing of several less common pore-forming agents (lycopodium, coffee, fl our and semolina, poppy seed), which are of potential interest from the viewpoint of size, shape or availability. The performance of these new PFAs is compared to that of starch, which has become a rather popular PFA for ceramics during the last decade. The PFAs investigated in this work are in the size range from 5 ?m (rice starch) to approximately 1 mm (poppy seed), all with more or less isometric shape. The burnout behavior of PFAs is studied by thermal analysis, i.e. thermogravimetry and differential thermal analysis. For the preparation of porous alumina ceramics from alumina suspensions containing PFAs traditional slip casting (into plaster molds) and starch consolidation casting (using metal molds) are used in this work. The resulting microstructures are investigated using optical microscopy, combined with image analysis, as well as other methods (Archimedes method of double-weighing in water, mercury intrusion porosimetry).

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Tepamat, Thanakorn, Thanakorn Wasanapiarnpong, Pornapa Sujaridworakul, and Charusporn Mongkolkachit. "Fabrication of Zeolite Na-A and Activated Carbon Composites by Slip Casting for Drinking Water Filtration." Key Engineering Materials 659 (August 2015): 299–303. http://dx.doi.org/10.4028/www.scientific.net/kem.659.299.

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Hybrid composite for drinking water filter aids were prepared by slip casting method. The slip was prepared from the mixture of 17.41% of zeolite Na-A, 17.41% of activated carbon, 0.35% of ZnO nanoparticles, 8.7% of phenolic resin, 0.54% carboxymethyl cellulose and 55.59% of reversed osmosis water. The slip was mixed in a high speed ball mill for 15, 30, 45 and 60 minutes and was then poured into plaster molds for 3 hours in order to maintain hollow casting. The green body was dried and fired at several of firing temperature of 600, 650, 700 and 750 °C. The major characteristics of the composite filter were characterized as: mechanical strength, morphology, pore diameter and ion exchange ability by three points bending, scanning electron microscopy (SEM), mercury porosimetry and inductive coupled plasma-optical emission spectroscopy (ICP-OES), respectively.

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Богатко, Н. М., and Н. І. Сахнюк. "Вплив санітарно-гігієнічного стану холодильних камер м’ясопереробних підприємств на безпечність м’ясної сировини за її зберігання." Вісник Полтавської державної аграрної академії, no. 1 (March 28, 2013): 106–9. http://dx.doi.org/10.31210/visnyk2013.01.28.

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Технологічні режими охолодження м’яса в охолоджувальній (t = -1 ºС) та холодильній (t = -12 ºС) камерах не чинять бактеріостатичний вплив на життєдіяльність плісеневих грибів. Найбільша зараженість плісеневими грибами повітряного середовища та штукатурки стін камер (охолоджувальних і холодильних) спостерігалася в їх нижній частині на висоті 0,5 м від підлоги. Дотримання вимог технологічних процесів зберігання м’ясної сировини, якісна дезінфекція забезпечать задовільний санітарно-гігієнічний стан охолоджувальних та холодильних камер. Technological modes of meat cooling in the cooling (t = -1 ºC) and cold (t = -12 ºC) cells do not have a bacteriostatic effect on the life of molds. Most fungi contamination of air and plaster walls of the chamber (cooling and refrigeration) was observed in their lower end at a height of 0.5 m above the floor. Compliance with process storage of raw meat, high-quality disinfection provide satisfactory sanitary conditions of cooling and cold storage.

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Sanewirush, U. Sangwanna, M. Buaheepkaew, O. Kosasang, and P. Saewong. "Properties of Waste Derived Mullite." Materials Science Forum 544-545 (May 2007): 605–8. http://dx.doi.org/10.4028/www.scientific.net/msf.544-545.605.

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Waste sediment (WS) from three different aluminum factories and rice husk ash (RHA) from power plants are used as precursors. Each WS is calcined to remove structural water then mixed and wet milled with RHA by 70 wt% until a homogeneous slip is obtained. The samples are formed by means of slip casting in plaster molds and fired at 1400 °C for 2 hours. The fired samples normally contain ~94 wt% mullite, 6 wt% residual silica and small amount of oxides of alkali and alkaline earth elements. It is found that their density and flexural strength are affected by alkali and alkaline earth contents and generally range from 1.53 to 2.38 g/cm3 and 18.11 to 76.37 MPa, respectively. While thermal expansion coefficient varies from 5.78 x 10-6 to 8.16 x 10-6 /°C and thermal shock resistance (T) from =200 to 300 °C.

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Landek, Darko, Lidija Ćurković, Ivana Gabelica, Mihone Kerolli Mustafa, and Irena Žmak. "Optimization of Sintering Process of Alumina Ceramics Using Response Surface Methodology." Sustainability 13, no. 12 (June 14, 2021): 6739. http://dx.doi.org/10.3390/su13126739.

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In this work, alumina (Al2O3) ceramics were prepared using an environmentally friendly slip casting method. To this end, highly concentrated (70 wt.%) aqueous suspensions of alumina (Al2O3) were prepared with different amounts of the ammonium salt of a polycarboxylic acid, Dolapix CE 64, as an electrosteric dispersant. The stability of highly concentrated Al2O3 aqueous suspensions was monitored by viscosity measurements. Green bodies (ceramics before sintering) were obtained by pouring the stable Al2O3 aqueous suspensions into dry porous plaster molds. The obtained Al2O3 ceramic green bodies were sintered in the electric furnace. Analysis of the effect of three sintering parameters (sintering temperature, heating rate and holding time) on the density of alumina ceramics was performed using the response surface methodology (RSM), based on experimental data obtained according to Box–Behnken experimental design, using the software Design-Expert. From the statistical analysis, linear and nonlinear models with added first-order interaction were developed for prediction and optimization of density-dependent variables: sintering temperature, heating rate and holding time.

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SILVA, Thalisson Saymo de Oliveira, Urias da Silva VASCONCELOS, Gregório Antonio Soares MARTINS, Valdimar da Silva VALENTE, and Carmem Dolores Vilarinho Soares de MOURA. "Conducts of disinfection, pouring and storage of irreversible hydrocolloid impressions by undergraduate students." Revista de Odontologia da UNESP 45, no. 1 (January 26, 2016): 1–6. http://dx.doi.org/10.1590/1807-2577.06215.

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Abstract Introduction Obtaining dental models that accurately represent the molded oral tissue requires professional attention, especially when using irreversible hydrocolloid as a molding material. Objective To evaluate the conducts of undergraduate dental students at different internships for the disinfecting procedures, pouring, and storage of irreversible hydrocolloid impressions. Material and method This is an observational, cross-sectional and descriptive study with a census sample of 89 students enrolled in the supervised internships I, II, III and IV. Data collection was performed using a structured questionnaire containing eight questions. Data were analyzed at the 5% significance level. Result Most of the students (88.8%) performed the disinfection procedure, for which the most widely used method (64.6%) was the application of sodium hypochlorite 1% spray stored in a sealed container. The most common disinfection time was 10 minutes (86.1%). Students in the early internships performed better in regard to the proportion of water/plaster to be used compared with students in the final internships. At all internships, pouring and storage of the ensemble of mold and model were neglected during the setting reaction. There was a statistically significant association between the stage and the disinfection method, the ratio of water/powder and pouring of the model (p<0.05). Conclusion Students exhibited appropriate conduct of disinfection; however, they should be encouraged to use evidence-based clinical practices in order to improve the procedures of pouring and storage of irreversible hydrocolloid molds.

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Ángeles, Jose Javier. "Las técnicas escultóricas de reproducción como medio de integración para alumnado con discapacidad." eari. educación artística. revista de investigación, no. 10 (December 20, 2019): 21. http://dx.doi.org/10.7203/eari.10.14228.

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Resumen. El siguiente artículo es una descripción interpretativa de una experiencia basada en la realización de un taller de técnicas de reproducción escultórica a partir de moldes de alginato, dirigido al alumnado con necesidades educativas especiales del Programa Específico de Formación Profesional Básica (PEFPB), realizado en un instituto de enseñanza secundaria. Se ha llevado a la práctica una metodología de interacción colectiva, monitorizada por los profesores del centro, en la que se ha empleado alginato dental como material para la confección de moldes, el cual, al ofrecer unas cualidades de copia excepcionales, permite al alumnado experimentar de manera manipulativa y visual todos los cambios que la materia comprende desde el proceso de mezcla de polvo y agua hasta la obtención de la reproducción. Las introducciones y explicaciones impartidas han sido simplificadas para obtener una mejor lectura y comprensión por parte del alumnado, introduciendo como ejemplo imágenes de obras escultóricas obtenidas mediante este procedimiento artístico. Además, se han realizado pequeñas demostraciones previas a la actividad para que el alumnado analice de forma visual cómo se manipula la materia, planteando como objetivo la reproducción de su propia mano en escayola. Cuando los conceptos y lenguajes artísticos se adaptan a las capacidades y necesidades del alumnado, hacen del aula un lugar de integración y cooperación, en el que los alumnos se introducen en experiencias visuales y manipulativas con las que descubren nuevos mecanismos de expresión. Palabras clave: integración, discapacidad, escultura, alginato, moldes, autoestima. Abstract: The following article is an interpretative description of a workshop devoted to sculpture reproduction based on alginate moulds addressed to students with special educational needs within the Specific Programme of Basic Vocational Training at a secondary education high-school. This workshop, supervised by teachers at the high-school, was performed following an interactional collective approach and using dental alginate for the production of moulds. Offering exceptional reproduction features, this material allowed the students to participate in a sensorial experience by means of the observation of all the changes that it suffers; from the mixing of alginate powder and water to the composition of the reproduction itself. The instructions and explanations given were simplified to obtain a better understanding of the students. Different images showing examples of sculpture works obtained by means of this technique were also provided. I addition, prior demonstrations were carried out so that the students could visually analyse how the material should be handled, suggesting the making of a plaster reproduction of their own hands. When concepts and artistic languages meet the student’s needs and capacities, they make the classroom a place for integration and cooperation where students live sensorial experiences which help them discover new ways of expression. key words: integration, disability, sculpture, alginate, molds, self-esteem. DOI: http://dx.doi.org/10.7203/eari.10.14228

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Vesper, Stephen, Larry Wymer, David Cox, and Gary Dewalt. "Populations of some molds in water-damaged homes may differ if the home was constructed with gypsum drywall compared to plaster." Science of The Total Environment 562 (August 2016): 446–50. http://dx.doi.org/10.1016/j.scitotenv.2016.04.067.

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Guiraldo, Ricardo, Sandrine Berger, Rodrigo Caixeta, Eloisa Souza, Murilo Lopes, Alcides Júnior, Sandra Moura, and Mário Sinhoreti. "Influence of the Disinfection Technique in Detail Reproduction and Dimensional Change of Plaster Casts Obtained from Different Alginate Impression Material Molds." British Journal of Medicine and Medical Research 17, no. 9 (January 10, 2016): 1–8. http://dx.doi.org/10.9734/bjmmr/2016/28035.

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Mize, Ramey. "Sacred Substantiations: Lincoln Casts and Statuary in the American Imagination." Contemporaneity: Historical Presence in Visual Culture 8 (October 30, 2019): 39–56. http://dx.doi.org/10.5195/contemp.2019.287.

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On March 31, 1860, Abraham Lincoln waited in the studio of Leonard Wells Volk as a plaster mold hardened around his face and head. After one hour, Volk removed the mold; he later repeated the process for Lincoln’s hands. The resulting life casts elicited profound emotional reactions in those who saw them. Augustus Saint-Gaudens recognized and capitalized on their invaluable status as candid indexes of Lincoln’s likeness in his 1887 Chicago monument, Abraham Lincoln: The Man. In the words of sculptor Lorado Taft, “It does not seem like a bronze. . . . One stands before it and feels himself in the very presence of America’s soul.” It was also Saint-Gaudens who amplified the casts’ influence through the manufacture of a prized series of thirty-three bronze replicas. The actual and imagined characteristics of these casts—their sense of possessing a “soul,” and their physical manifestation of Lincoln’s touch—all warrant consideration of their place within the larger tradition of holy relics. This paper posits the Lincoln casts as “contact relics” and establishes the generative potential of such a numinous categorization for American audiences, especially in the wake of the Civil War. Volk’s direct impressions of Lincoln’s visage and hands provided the “blueprints,” so to speak, for an astonishingly wide variety of sculptural manifestations—from the iconic Lincoln Memorial (1920) by Daniel Chester French to Abraham Lincoln (1917) by George Grey Barnard. This essay argues that the cultural impact of this sculptural genealogy is largely indebted to the casts’ material substantiations of Lincoln’s bodily presence and touch. Indeed, by situating these objects between medieval and modern modes of viewing, it will become clear that the casts, as progeny of the original life molds, afforded an affective, even remedial, authenticity for subsequent Lincoln monuments in the American imagination.

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Boles, Jessika, Maile Jones, Jenna Dunbar, and Jessica Cook. "Defining Legacy: The Perceptions of Pediatric Health Care Providers." Clinical Pediatrics 59, no. 11 (July 13, 2020): 1004–10. http://dx.doi.org/10.1177/0009922820940808.

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Legacy building interventions like plaster hand molds are offered in most children’s hospitals, yet little is known about how the concept of legacy is understood and described by pediatric health care providers. Therefore, this study explored pediatric health care providers’ perceptions of legacy at an academic medical center to ensure that future legacy interventions are evidence-informed and theoretically grounded. An electronic survey featuring three open-ended questions and two multiple-choice questions with an option for free text response was completed by 172 medical and psychosocial health care providers. Analysis yielded four themes: (1) legacy is intergenerational, enduring, and typically associated with end-of-life; (2) legacies articulate the impacts on others for which one is known and remembered; (3) legacies can be expressed through tangible items or intangible qualities; and (4) legacies are informed and generated by family relationships and work experiences. By understanding legacy as a personally and professionally contextualized experience, health care providers can better assess and meet the legacy needs of hospitalized pediatric patients and families.

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Murata, Yasuhiko, and Masahiro Kuramochi. "Development of Heating and Cooling Injection Mold with Far-Infrared Radiation Heater." International Journal of Automation Technology 10, no. 1 (January 4, 2016): 79–86. http://dx.doi.org/10.20965/ijat.2016.p0079.

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Several rapid heating and cooling molding methods have been developed for practical use to improve the surface quality of plastic injection-molded products. These methods, however, need expensive equipment and complex molds that require vast know-how, and hence cannot be applied easily to actual production. In order to establish a molding method in which the mold’s cavity surfaces can easily be heated, we designed and manufactured a heating and cooling injection mold with a far-infrared radiation heater. Using this mold, we molded a high-impact polystyrene molded product, and found that the use of such a mold could lead to a decrease in the V-shaped groove depth of weld lines, as well as to an improvement in the transcription of the mold’s cavity surface quality onto the molded product. We also carried out tensile tests on the molded products to confirm whether the use of such a mold could increase the product’s elongation at break.

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Mesquita, Rafael Agnelli, and Reinhold S. E. Schneider. "Tool Steel Quality And Surface Finishing of Plastic Molds." Exacta 8, no. 3 (February 16, 2011): 307–18. http://dx.doi.org/10.5585/exacta.v8i3.2442.

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Plastic industry is today in a constant growth, demanding several products from other segments, which includes the plastic molds, mainly used in the injection molding process. Considering all the requirements of plastic molds, the surface finishing is of special interest, as the injected plastic part is able to reproduce any details (and also defects) from the mold surface. Therefore, several aspects on mold finishing are important, mainly related to manufacturing conditions – machining, grinding, polishing and texturing, and also related to the tool steel quality, in relation to microstructure homogeneity and non-metallic inclusions (cleanliness). The present paper is then focused on this interrelationship between steel quality and manufacturing process, which are both related to the final quality of plastic mold surfaces. Examples are discussed in terms of surface finishing of plastic molds and the properties or the microstructure of mold steels.

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Mesquita, Rafael Agnelli, and Reinhold S. E. Schneider. "Tool Steel Quality And Surface Finishing of Plastic Molds DOI: 10.5585/exacta.v8i3.2442." Exacta 8, no. 3 (February 16, 2011): 307–18. http://dx.doi.org/10.5585/exactaep.v8i3.2442.

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Plastic industry is today in a constant growth, demanding several products from other segments, which includes the plastic molds, mainly used in the injection molding process. Considering all the requirements of plastic molds, the surface finishing is of special interest, as the injected plastic part is able to reproduce any details (and also defects) from the mold surface. Therefore, several aspects on mold finishing are important, mainly related to manufacturing conditions – machining, grinding, polishing and texturing, and also related to the tool steel quality, in relation to microstructure homogeneity and non-metallic inclusions (cleanliness). The present paper is then focused on this interrelationship between steel quality and manufacturing process, which are both related to the final quality of plastic mold surfaces. Examples are discussed in terms of surface finishing of plastic molds and the properties or the microstructure of mold steels.

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CAKMAKCI, SONGUL, BULENT CETIN, MUSTAFA GURSES, ELIF DAGDEMIR, and ALI ADNAN HAYALOGLU. "Morphological, Molecular, and Mycotoxigenic Identification of Dominant Filamentous Fungi from Moldy Civil Cheese." Journal of Food Protection 75, no. 11 (November 1, 2012): 2045–49. http://dx.doi.org/10.4315/0362-028x.jfp-12-107.

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Moldy Civil is a mold-ripened variety of cheese produced mainly in eastern Turkey. This cheese is produced with Civil cheese and whey curd cheese (Lor). Civil cheese has had a geographical presence since 2009 and is manufactured with skim milk. In the production of Moldy Civil cheese, Civil cheese or a mixture of Civil and Lor cheese is pressed into goat skins or plastic bags and ripened for 3 months or longer. During the ripening period, natural contaminating molds grow on the surface of and inside the cheese. In this study, 186 mold strains were isolated from 41 samples of Moldy Civil cheese, and 165 of these strains were identified as Penicillium roqueforti. Identification and mycotoxicologic analyses were conducted using morphotypic and molecular methods. PCR amplicons of the ITS1-5.8S-ITS4 region were subjected to sequence analysis. This research is the first using molecular methods on Moldy Civil cheese. Mycotoxicologic analyses were conducted using thin-layer chromatography, and random amplified polymorphic DNA genotypes were determined using the ari1 primer. Of 165 isolates, only 28 produced no penicillic acid, P. roqueforti toxin, or roquefortine.

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Barrios-Muriel, Jorge, Francisco Romero-Sánchez, Francisco Javier Alonso-Sánchez, and David Rodríguez Salgado. "Advances in Orthotic and Prosthetic Manufacturing: A Technology Review." Materials 13, no. 2 (January 9, 2020): 295. http://dx.doi.org/10.3390/ma13020295.

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In this work, the recent advances for rapid prototyping in the orthoprosthetic industry are presented. Specifically, the manufacturing process of orthoprosthetic aids are analysed, as thier use is widely extended in orthopedic surgery. These devices are devoted to either correct posture or movement (orthosis) or to substitute a body segment (prosthesis) while maintaining functionality. The manufacturing process is traditionally mainly hand-crafted: The subject’s morphology is taken by means of plaster molds, and the manufacture is performed individually, by adjusting the prototype over the subject. This industry has incorporated computer aided design (CAD), computed aided engineering (CAE) and computed aided manufacturing (CAM) tools; however, the true revolution is the result of the application of rapid prototyping technologies (RPT). Techniques such as fused deposition modelling (FDM), selective laser sintering (SLS), laminated object manufacturing (LOM), and 3D printing (3DP) are some examples of the available methodologies in the manufacturing industry that, step by step, are being included in the rehabilitation engineering market—an engineering field with growth and prospects in the coming years. In this work we analyse different methodologies for additive manufacturing along with the principal methods for collecting 3D body shapes and their application in the manufacturing of functional devices for rehabilitation purposes such as splints, ankle-foot orthoses, or arm prostheses.

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Auechalitanukul, Chiraporn, Ryan McCuiston, Ton Sukantowong, Wachira Wachirapanee, and Treepak Surmpakdeekul. "Effect of Waste-Derived Calcium Sulfate Additions on the Tribological Properties of Sintered Steel-Based Material." Key Engineering Materials 798 (April 2019): 146–51. http://dx.doi.org/10.4028/www.scientific.net/kem.798.146.

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Abstract:

This study examined the effect of waste-derived calcium sulfate additions (2 to 8 weight percent) on the tribological properties of a sintered high-carbon steel material, commonly used for frictional applications. The calcium sulfate powder was obtained by crushing and subsequent calcination of waste plaster molds previously used for slip casting of ceramics. Samples were made using the powder metallurgy method. Powder mixtures were uniaxially die compacted and sintered at 1,100°C for 30 minutes in a reducing atmosphere. It was found that the density of the samples decreased with increased amounts of calcium sulfate. This was due to the lower theoretical density of the calcium sulfate as well as volumetric expansion of the samples. Ball-on-disc tribological testing was performed at room temperature. The addition of calcium sulfate resulted in an increase of the kinetic friction coefficient. The measured wear volume was slightly reduced with the addition of calcium sulfate less than 6 weight percent, beyond which the wear increased. The hardness of the samples was reduced with the addition of calcium sulfate. Increased calcium sulfate content decreased the sample deformation resistance while increasing the kinetic friction coefficient and the wear. This was likely due to the microstructural changes of the samples, which will be discussed.

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Chen, Guang Xia, Xiao Yan Zeng, Ze Min Wang, Kai Guan, and Chang Wen Peng. "Fabrication of Removable Partial Denture Framework by Selective Laser Melting." Advanced Materials Research 317-319 (August 2011): 174–78. http://dx.doi.org/10.4028/www.scientific.net/amr.317-319.174.

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Abstract:

The removable partial denture framework is very complex in shape with many curved surfaces, which is a very important assistant tool in prosthodontics. Generally, frameworks are fabricated by single piece basing on mould by traditional cast technology, which has many shortages of multiple steps, time cost and defects such as sand adheres, inner holes, cracks and segregation etc. As a novel method, selective laser melting (SLM) rapid prototyping technology has the advantages of short manufacturing cycle, high precision and flexibility, simple fabrication arts, which can be used to replace the conventional cast technology in the areas of prosthodontics. A SLM system was designed and developed by ourselves, which is consisted of an Yb-fiber laser, an optical scanner, a powder coating device, a gas purification system and a control system, the process parameters were investigated systematically and optimized, finally fabricated removable partial denture frameworks with stainless steel and titanium materials successfully by using the SLM system under optimized parameters. The tests showed that the frameworks have an average dimension precision of ±0.172mm. The wearing experiments on the plaster mouth molds demonstrated the removable partial denture frameworks fabricated by SLM can be fully applied to clinic after some post- processing procedures.

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Li, Shan, Liang Xu, and Yu Qi Wang. "Design and NC Manufacturing of Plastic Injection Mold Based on UG Software." Advanced Materials Research 630 (December 2012): 163–66. http://dx.doi.org/10.4028/www.scientific.net/amr.630.163.

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On the platform of the UG Software’s CAD/MoldWizard/CAM components, the whole process of design and NC manufacturing of the plastic injection mold of a hair dryer’s shell was completed. The CAD/CAM process of the plastic injection mold was introduced by the practical application. The large advantage of the UG platform over the traditional method in the field of plastic injection molds’ design and manufacturing was reflected. The plastic injection molds’ design and manufacturing is a great challenge to the traditional design and manufacturing method, and the UG solutions can promote mold manufacturers’ ability of design and manufacturing remarkably.

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Journal articles on the topic 'Plaster molds'

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