Effects of process parameters on quality of ultrafine WC/12Co injection molded compacts

• We use Taguchi experiments to optimize WC/Co powder injection process parameters.
• We examine process parameters' effects on quality of molded compacts.
• Confirmation experiments proved that statistical model is reliable.
• The quality of molded compacts mostly depends on characteristics of binder.

The effects of process parameters for ultrafine WC/12Co cemented carbide powder injection molding (PIM) on quality of molded compacts were investigated in this study. The quality characteristics are divided into compacts' appearance, flexural strength and density. The Taguchi method and ANOVA were taken to optimize the process parameters and to identify the most significant factors. The experimental results revealed that the flexural strength of injection molded compacts is significantly affected by all of chosen injection parameters. The sensitivity of flexural strength is closely related to the characteristics of binder. The density of compacts is mostly affected by injection pressure. The stability of density is attributed to the homogeneity of feedstock and the wettability between organic binder and WC/12Co powder mixture. It is found that, in a certain degree, the flexural strength of compacts is higher with the density increasing. Thus, the flexural strength is chosen as the main quality characteristic of injection molded compacts. It is proved by the confirmation experiments that the statistical model used to predict the value of flexural strength of compacts is reliable.