EFFECT OF STUCCO APPLICATION METHOD ON THE MECHANICAL PERFORMANCE AND MICROSTRUCTURE OF INVESTMENT CASTING SHELLS

摘要

This paper presents the results of research that is being carried out within the EU-funded MedCast Project “Development of Foundry Casting Methods for Cost-Effective Manufacture of Medical Implants” (MedCast). The partnership is led by DePuy Johnson & Johnson with two university collaborators. Research has focused on understanding the influence of stucco application methods on the performance of investment casting shells. Weibull statistics were adopted to develop a robust testing method for the mechanical strength of the shells. The Weibull plots showed the presence of two slopes when the sample was tested with the prime coat in tension, indicating two different failure mechanisms. In both testing orientations, 4 point bending proved a more reliable method of testing. Statistical methods were used to understand the main inf luences of stucco application on both prime and back up layers of the shell system. The flexural strength, permeability, edge strength and overall weight of the samples were analysed using this approach. It was found the rainfall sanding method gave thinner stucco layers compared to fluidised bed stuccoing yet gave stronger and denser shells.