Temperature and power loading influence to the injection of bimodal stainless steel powder mixtures

摘要

Investigation on the influence of temperature and powder loading to the injection of Metal Injection Molding (MIM) feedstock prepared with bimodal powder mixture is presented. Feedstocks used were a mixture of coarse and fine stainless steel powder with composition of 30 and 70 % volume respectively mixed with polyethylene glycol, polymethyl methacrylate and stearic acid as a binder in a sigma blade mixer. The stainless steel powder has been loaded to 64 and 65 % volume before it was injection molded to form a MIMA tensile specimen with Battenfeld BA 250 CDC plastic injection-molding machine. The as-molded density was measured with Archimedes water immersion method according to the MPIF Standard 42. The injection temperature was varied from 120 to 150 癈 while the injection pressure remains at 350 bars. The three-point bend test was performed using INSTRON 5567 to measure the green strength according to the MPIF Standard 15. Results found that high powder loading bimodal feedstock is more temperature sensitive and the injection temperature has less significant to the as molded strength and density.