Dewaxing of ABS rapid prototype pattern for ceramic investment casting of proximal humerus

Abstract

Orthopedic implants can be defined as medical devices used to replace or provide fixation of bone or to replace articulating surfaces of a joint. Many proximal humerus bone cases require almost immediate/short lead time surgery. Thus rapid respond from the manufacture is very crucial. The manufacture of surgical implant often requires the use of machining process. Current trend shows that preform either from casting or forging is preferred to reduce machining cost and time. It is expected that by employing rapid manufacture using rapid prototyping and investment casting process could expedite the manufacturer to surgery time. The objective of this project is to evaluate the effect of dewaxing time on collapsibility characteristic of solid and hollow constructed rapid prototyped proximal humerus ABS pattern.FDM2000 machine was used to build the ABS patterns. Acrylonitrile Butadiene Styrene (ABS) P400 was used for pattern material in this study. Output responses investigated were collapsibility, expansion defects. ABS hollow and solid pattern are prepared and are subjected to dewaxing in different time and temperature. The ABS hollow and solid pattern were compared based on the dewaxing process results, ceramic shell defects. The best pattern material according to the optimum time and temperature was chosen based on the results and compared with the reference process. This study is expected to assist the investment caster to estimate the decomposition temperature and allowance required in preparing a mould from ABS pattern as well as in the initial CAD drawings to produce a final casting with minimal dimensional in accuracy. It is hoped that the outcome of this study will assist the casting industries especially in biomedical in using the advanced product support tools using CAD and RP technology for higher productivity and quality products.