Literatura científica selecionada sobre o tema "Freeform Powder Molding"

The capability of producing injection tool inserts using an additive manufacturing (AM) technology was investigated. Using electron beam melting (EBM), the restriction of drilling straight cooling channels could be eliminated and freeform channels with sufficient powder removal were achieved. EBM parameters and the design of the cooling channels strongly influence the sintering degree of the powder trapped in the channels and thus the ease of the powder removal. Despite the low heat conductivity of the new inserts made from Ti6Al4V, the cooling performance was the same as for the conventional inserts. However, the use of Ti6Al4V is advantageous, since the expanding agent used in injection molding is very corrosive.

Great improvements are continuously being made in the solid free form fabrication (SFF) industry in terms of processes and materials. Fully functional parts are being created directly with little, if any, finishing. Parts are being directly fabricated with engineering materials such as ceramics and metals. This thesis aims to facilitate a substantial advance in rapid prototyping capabilities, namely that of fabricating parts with continuously heterogeneous material compositions. Because SFF is an additive building process, building parts layer-by-layer or even point-by-point, adjusting material composition throughout the entire part, in all three dimensions, is feasible. The use of fine powders as its build material provides the potential for the Selective Laser Sintering (SLS), ThreeDimensional Printing (3DP), and Freeform Powder Molding (FPM) processes to be altered to create continuously heterogeneous material composition. The current roller distribution system needs to be replaced with a new means of delivering the powder that facilitates selective heterogeneous material compositions. This thesis explores a dense phase pneumatic conveying system that has the potential to deliver the powder in a controlled manner and allow for adjustment of material composition throughout the layer.

Master of Science

Solid freeform fabrication technology has shown a great deal of promise for the plastic injection molding industry due to its ability to produce complex geometry tooling relatively quickly. However, one shortcoming of metal-based SFF processes is that they have difficulty producing parts with acceptable surface quality. As such, secondary operations, such as machining, are frequently required thereby increasing fabrication time and cost. In addition, there is variation in the surface quality that is dependent upon the surface orientation during the build process. For example, parts produced using the metal-based 3-D printing process have vertical faces with a typical roughness 52% greater than the horizontal faces. This work investigates the effects on part surface quality resulting from the application of a contact surface "blank" to the part free surfaces during the infiltration stage of a powder metalbased rapid manufacturing process. Specifically, the effects of "blank" surface roughness and contact pressure are studied with respect to resultant surface roughness and uniformity of the infiltrated part. Application of a smooth contact surface on vertical faces resulted in Ra values at least 25% lower than that of vertical free surfaces. It was also revealed that there is a correlation between surface roughness of the blank and the surface roughness of the infiltrated part. Such blanks could be used to impart desired surface finish and texture to critical surfaces of a mold tool.

Bio-inspired products and devices take their inspiration from nature [Gold00]. Current mechanical engineering curricula do not cover manufacturing techniques and principles needed to develop such products and devices. We have been enhancing the mechanical engineering undergraduate curriculum by integrating recent advances in the manufacturing of bio-inspired products and devices through the following activities: 1. Insert a new sequence of instructional materials on bio-inspired concepts into the mechanical engineering curriculum. 2. Disseminate the materials developed for the new modules and course notes through a dedicated web site. As a result of the curriculum enhancement, a new generation of mechanical engineers will acquire the knowledge necessary to develop products and conduct research for a wide variety of applications utilizing bio-inspired concepts. The project (1) integrates emerging manufacturing technologies based on biological principles into the Mechanical Engineering curriculum, (2) utilizes multi-media technology for disseminating course content, and (3) trains graduate students and faculty participating in its implementation in an emerging technology and thereby contribute to faculty development. Specifically, curriculum is being developed that discusses the following manufacturing technologies and principles: 1. Concurrent Fabrication and Assembly: Manufacturing techniques and principles, such as solid freeform fabrication, compliant mechanisms, and multi-stage molding, that can eliminate the manufacturing and assembly of individual components as is the case for almost all natural systems. 2. Self Assembly: Principles for manufacturing a variety of products from a few building blocks using bio-inspired techniques such as templating and supramolecular chemistry. 3. Functionally Graded Materials: Bio-inspired development of new products through the gradual variation of material properties at multiple length scales through manufacturing processes such as sputtering and powder processing. The curriculum development effort makes two significant contributions to mechanical engineering education: (a) integration of a new research on bio-inspired products and devices into the mechanical engineering curriculum through new courses and revision of existing courses, (b) development of new instructional material for mechanical engineering education based on bio-inspired concepts. There are also broader impacts in the following areas: (a) undergraduate students who might not otherwise puruse studies in mechanical engineering will be attracted to the multidisciplinary area of bio-inspired products, (b) dissemination of the curriculum enhancement through conference presentations, a workshop, and dedicated web site, and (c) a biologically-oriented pedagogical approach to mechanical engineering education that ensures broader access to the knowledge needed to enhance the interest and skills of future engineers and researchers educated through this research program.

Laser aided direct metal/material deposition (DMD) process, one of the technologies based on laser cladding, has demonstrated the ability to make a metal component directly from a 3-D CAD model. DMD process is achieved with a laser system combined with a NC machine tool or laser-robot system. Making metallic parts directly, designer can reduce unnecessary steps such as mock-up and molding. In the sense, DMD process is rather a rapid production technique than a rapid prototyping process. With continued advancement, DMD process, one of the leading solid freeform fabrication techniques, has demonstrated the ability to make a metal part with heterogeneous components directly from a CAD model. One unique advantage of the process is that building different metallic parts in same object can be achieved alternating metal powders. The advantage gives designers better quality of products than others can offer. Another attractive point is that some features such as cooling channel, heat sinks, sensors, fibers, and even hard phases for composites can be embedded during the process. This paper summarizes the fundamentals of the process, process control and influence of process parameters, and reports some examples produced utilizing the technique with the characteristics of fabricated parts.