Some Investigations to Improve the Performance in Rapid Investment Casting Process

Abstract

The rapid prototyping technologies (RP) is very useful when a limited number of pieces are promptly required as: in making/ testing prototypes, design iterations, design optimizations. The fused deposition modeling (FDM) is one of the RP technologies that can use thermoplastic for making sacrificial patterns used in investment casting process, is used to produce parts with controlled dimensional tolerances. In the present research, study of the product prepared with FDM assisted IC process has been done and issues in procedure have been addressed & resolved. This study includes comparisons of (i) FDM pattern materials such as PLA & ABS, (ii) block mould casting & shell mould casting, (iii) wax pattern, wax coated polymer pattern and uncoated plastic pattern, have been done. This work also shows the feasibility of direct shell printing through 3D ceramic printing with extrusion and SLS based processes. FDM pattern based RIC is faster & economical. Shell mould casting gives better result than block mould casting. Ceramic shell making process can be improved by optimized ceramic composition, drying time, and proper orientation. A thin wax coating on plastic patterns can improve the dimensional accuracy and surface finish of the investment castings made by using FDM based patterns. By varying infill rate minimum density of FDM pattern can be employed with sufficient strength. Polymer pattern are more robust and strong than wax pattern so not damaged during operation & handling.