SOME INVESTIGATIONS TO IMPROVISE RAPID INVESTMENT CASTING PROCESS

Abstract

Investment casting (IC), also called precision casting process has been utilized to manufacture jewellery, art castings and weapons during the ancient times. In present times, its applications range from art castings & jewellery to turbine blades & many more scientific & industrial components because of its capability to generate parts with controlled dimensional tolerances. But in traditional IC, a metal die is essential to make sacrificial wax patterns & the fabrication of that die consumes lots of time & money, thus economically suitable for mass production only. With the advent of various techniques of Rapid prototyping such as FDM (Fused Deposition Modeling) in recent years, it’s became possible to obtain plastic based sacrificial patterns that helps the IC process in eradicating the expensive tooling requirement for making wax patterns & thus making IC available for customised & low volume products too. The utilization of pattern generated through FDM process in IC process to produce metal cast parts is known as Rapid Investment Casting (RIC), which is very helpful when a smaller number of pieces are required such as fabricating & testing prototypes, medical implants, design iterations etc. The FDM is among the most suited RP technologies which can utilize different polymers for generating sacrificial patterns to be used in IC process. In the present study (i) the parts prepared with FDM assisted IC and effect of various process parameters on pattern has been evaluated and studied (ii) Various FDM pattern materials such as PLA & ABS have been compared (iii) Comparison of types of IC processes, e.g. block mould casting, plaster mould casting & shell mould casting has been carried out to select the most suitable one (iv) FDM parameters like infill rate is optimized & minimum infill for sacrificial pattern that can serve the requirement has been found (v) Effect of FDM pattern infill rate & number of slurry coatings used in making shells, on surface roughness & hardness of cast is also evaluated.