An Investigation of the Optimum Insert Diameter/Molding Diameter Ratio by Inserted Powder Injection Molding
Oğuz Yılmaz Kamran Samet Harun Koçak Çetin Karataş
AbstractInserted powder injection molding (IPIM) is developed to produce a larger volume parts in powder injection molding (PIM). In this method, the injection process is carried out on the part called insert. Since the injection volume gets smaller, the debinding time decreases. However, the insert diameter/the molding diameter ratio (Di/Dm) is the important parameter in that method. There could occur crack in the injection side unless the ratio determines properly. In this study, the insert and injection’s materials is high speed steel (HSS) and WC-%9Co feedstock, respectively. Different amount of expansion occurs since the materials have different thermal expansion coefficients. This difference causes a thermal stress in the connection surface. If the resulting thermal stress exceeds the compressing strength of the material in the injection side, then thermal cracks occur. Mathematical calculations have been carried out to determine the optimum ratio of Di/Dm. In order to validate the calculations, finite element analysis was performed by ANSYS software. Theoretical results were supported with experimental studies. The risk of cracking in the injection side increases as the ratio of Di/Dm increases. As a result of the study, the optimum ratio of Di/Dm was determined as 0.45 for the part produced by PIM.