The Research Of Interfacial Wear Performance Of Mould Inserts During The Powder Injection Molding Of Feedstock

The product demand is increasing with the continuous development of powder injection molding technology, as a new type of near net-shape technology of powder metallurgy, the powder injection molding has been widely used. Affected by many factors, the mold wear is inevitable in the process of powder injection molding. Wear will not only affect the service life of the material and the reliability, but at the same time it will also affect the dimensional accuracy and surface quality of the injection products. So it is vitally significant to research the mold wear of powder injection molding.In this paper, by investigating the thermal and rheological properties of the feedstock, etc., the decomposition temperature of the feedstock, viscosity changing with the temperatures and shear rates were determined. Using a self-designed laboratory-scale experiment platform to examine the influence of mold interface wear behavior of the molten feedstock at200℃and80mm/s speed under different injection mold materials and runner sizes in the filling process of powder injection molding. And a14FW wear tester was also used to examine the influence of load, demolding temperature and demolding speed on the mold friction and wear properties, the wear mechanisms of different mold materials during the demolding process of powder injection molding were obtained. The main conclusions are as follows:(1) Through the thermo-gravimetric analysis and rheological characteristics of the feedstock, the results showed that the thermal decomposition of the feedstock was a multi-step decomposition process, the melting temperature of the feedstock was166.3℃, the binder started to degrade at a temperature of215.3℃, and the rheological properties showed that the feedstock had a good comprehensive performance at the temperature of200℃, so choosing200℃as the filling mold temperature of powder injection molding.(2) Different materials and different runner sizes presented different wear mechanisms in the mold filling process of powder injection molding. The mold material of H59was given priority to erosion wear and adhesive wear, while the40Cr was given priority to abrasive wear, and erosion wear and corrosion wear may occur. The wear volume of mold material was closely related to the runner section sizes, and the runner entrance worn more serious. (3) The results showed that the main wear mechanisms were adhesive wear and abrasive wear during the demolding process of powder injection molding, the40Cr showed typical abrasive wear, Mono-crystalline silicon exhibited adhesive wear and abrasive wear. The friction and wear properties of the mold material were affected by the load, demolding temperature and demolding speed.