Effects of injection molding parameter (temperature) on 316l stainless steel parts

• Main Author: Chua, Shi Wei.
• Other Authors: Loh Ngiap Hiang
• Format: Final Year Project
• Language: English
• Published: 2012
• Subjects: DRNTU::Engineering::Mechanical engineering
• Online Access: http://hdl.handle.net/10356/47613
• Institution: Nanyang Technological University

Powder injection molding (PIM) is a process consisting of four main steps: mixing, injection molding, debinding and sintering. Every step in this process is important for the outcome of the final product. A circular part with micro-structures was molded in this project. The dimensions of the micro-structure were: width 200 µm and height 120 µm. There were a total of eleven micro-structures in each molded part. Two feedstocks were used. The first feedstock consisted of 92 weight % 316L stainless steel powder and 8 weight % binder system. The second feedstock consisted of 91 weight % 316L stainless steel powder and 9 weight % binder system. The binder system consisted of: paraffin wax, ethylene vinyl acetate, low density polyethylene and stearic acid. The main focus of this project was to study the effects of injection molding parameters (temperature) on the characteristics of the molded parts. There were four different sets of injection molding parameters. The molded parts were compared to see the effects of different sets of molding parameters (with different barrel and mold temperature) on the quality of the micro-structures. The micro-structures were examined under scanning electron microscope (SEM) and the SEM micrographs were observed. Dimensions of the micro-structures were also measured and compared to the specified dimensions of the silicon mold insert. The molded parts were then sent for debinding and viewed under the SEM for debinding defects and shape retention of the micro-structures. Feedstock 1 with a higher powder loading of 92 weight % and 8 weight % binder system using set 4 molding parameters of higher barrel and mold temperatures (175 ℃ and 75 ℃, respectively) gave the best result: good filling of the micro-structures, good shape retention after debinding and no visual debinding defects.