Feature Article Design for Additive and Advance Simulation
for Toolingless Investment Casting with Additive Manufacturing Processes and for Complex Wax Production Tooling by Jiten Shah, Founder and President, Product Development & Analysis (PDA) LLC, Naperville, IL
T
oolingless castings using AM (printed wax, PMMA, PLA and SLA) offers tremendous design
freedom with feature placement, orientation and zero/negative/reverse draft. Part and feature consolidation after carefully understanding current casting higher order sub-assembly; form-fit and functionality can lead to a more complex one piece casting configuration, improving the final product performance at reducing cost and lead times. Figure 1 is an example of racing car aluminum housing with manifold cast integral design, eliminating machining, gasket, bolting and performance issues with bi-metals with different CTEs with traditional design.
Toolingless casting also offers
tremendous freedom with part orientation and rigging options. The gating can now be designed and simulated to ensure favorable cooling rate and micro-structure without excessive residual stress and tendency for any hot tearing in alloys prone to. Since tooling is not there, traditional trial and approach with AM methods can be cost prohibited and foundry engineer can gain extra confidence in getting the casting right at the first time, if he or she uses effectively casting process simulation tools. Current state of the art modeling technology not only simulates filling, solidification and cooling, but predicts local micro-structure, mechanical properties, residual stress and distortion with higher degree of confidence for complex shaped castings in various alloys and correlates well to the reality. Figure 2 shows an example of solidification pattern for an investment
18 ❘ March 2020 ®
Figure 1: Aluminum Racing Engine Housing With Manifold As One Piece Casting Design
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