Transcript Slide 1
Rapid Prototyping for Casting Aaron Agostino Mechanical Engineering – Union College Advisor – Professor Amy Hsiao, Ph.D Abstract Casting has been around since the Neolithic period, several thousand years ago, and through time has developed substantially. Lost wax casting is what I am basing my project on, though rather than using wax, ABS prototypes are the starting medium. My process begins by creating a 3D model, and from that part, I create a mold and cast the part. This project is aimed at getting a better working knowledge of casting and will move towards function by creating useful and intentional working parts as the process becomes more routine. Background As villages were first forming there was a developing need for specialized objects. Agricultural equipment, tools, jewelry, and many other products became necessary, and investment casting was there to meet the demands. Over time the methods were improved and experimentation led to improved technical knowledge. The techniques used two thousand years ago were nearly the same as those of today, though in the last hundred years our casting methods have been refined to meet the precision required of our society. By accounting for the properties of material microstructures and mechanizing the molding process, the demands for tighter tolerances and tougher specifications are attainable. Experimental Procedure ◦ ◦ ◦ ◦ ◦ ◦ ◦ ◦ Part conceptualized and created 3-dimensionally using SolidWorks Parts is exported as an .stl file to be dribbled on the rapid prototype machine Vents are created, dribbled, and adhered Mold is made around ABS part with a ceramic slurry Part is melted out of mold with torch and put in oven to completely evaporate Molten alloy is poured from crucible into warm mold to form part Mold is broken away leaving the part Vents and sprue are grinded off the surface of the part, leaving the final product Discussion This project has not been fully completed yet, but at this point there are some results that are worth looking into further. Through testing I found roughly at what temperature the ABS melts, and fortunately, it is below the temperature at which the gases are flammable. Knowing that this melting would be feasible opened up the possibility of this project. Another aspect of working with the ABS parts is the surface texture and tolerances. Though the parts have specific dimensions, the layering method limits the tolerance to 10 mils, and when improved surfaces require filler, tolerances increase further. The use of this method may not be practical for very deliberate products where material properties and accuracy are crucial, but often, early prototypes do not need high precision, and so, for these applications, the ability to quickly create a close likeness of the desired object is invaluable. Summary Progress so far has been limited due to resource accessibility, but in the next five months this project will develop from the basics of casting to the point where various materials are being alloyed and the mixtures may not be based on eutectic proportions. As this working knowledge of the process evolves, the specification of parts to applications will become more applied and researched. Next term there is the intention to collaborate with a fellow classmate who is studying harmonics so that we may investigate the effects of changing material ratios of the aluminum-copper alloy on the resulting tonal signal. If it works properly, we would be able to identify the type of alloy by its sound. References The History of Casting. Fine Art Foundry. 10/12/2005 http://www.kunstguss.ch/_html/eng/01_casting/01_03_history.html . J.L. Murray, Metals Handbook, 2nd Edition. J.R. Davis. Materials Park, OH: ASM International, 1998. Page 2.44.