Optimizing the Injectability of Parts Produced by Metal Powder Injection Molding (MIM)

PROJECT COST:

41 666 $

PRIMA CONTRIBUTION:

8 333 $

PROJECT DETAILS:

Pratt & Whitney Canada manufactures parts using the low-pressure powder injection molding (LPIM) process. This process produces a dense metal part from an initial mixture of metal powder and a binder, which may be polymeric or made from a wax-based mixture.
During an initial project funded by the Partnership Engagement Grant Program (NSERC-PEG) in collaboration with Pratt & Whitney Canada, Professor N. Demarquette and her team developed a procedure for the rheological characterization of metal powder/polymer binder mixtures used in the LPIM process. The results made it possible to characterize the powder/binder mixtures using a moldability index based on the polymer injection process. This parameter, derived from the rheological characterization of the mixtures, quantifies the mixtures’ ability to be injected. Although the absolute values of the moldability index for P&WC’s proprietary mixtures are confidential, the model was validated and then used to study the impact of mixture parameters on injectability and, ultimately, to predict a mixture’s injectability. During this initial SEP project, correlating the rheological results with full-scale injection results in molds allowed us to recognize the importance of mold parameters (surface finish, mold material, etc.).
This project therefore aims to develop tools to accurately quantify the impact of various external factors—such as the rheological properties of the mixture, the surface finish, and the thermal properties of the molds (i.e., different mold cavity configurations and different mixtures)—on the moldability of the mixtures, in order to determine the optimal injection molding conditions for the mixtures used at P&W.