Permeability Performance on Porous Structure of Injection Mold Fabricated by Metal Laser Sintering Combined with High Speed Milling

Abstract

Metal Laser Sintering Combined with High Speed Milling is the technology in which high speed cutting is united with the selective laser sintering process. By changing the conditions of laser beam irradiation, it is possible to build a sintered porous media which has a hole in an arbitrary part by this process. If the mold tool of this structure is used for injection molding, it is proved that the compressed air imprisoned in the mold and the gas coming out of resin are discharged from it, poor molding can be reduced. However, as sintered porous media is hard to control for the size and position of an ordered macroporous structure, it is difficult to build porous media with an ordered macroporous structure deliberately. This results in a smaller amount of airflow and a greater variation in airflow. In order to solve this problem, latticework is proposed as a new gas permeable structure in this paper. Different from a lower density sintered structure, metallic powder is sintered and fused using a laser beam with a high energy density, and fusion is carried out into the latticework structure. The fused gaps of the structure serve as a hole. Since each hole will keep the position and become the ordered macroporous structure even if lamination continues, the improvement in performance of gas permeability is expected. The airflow equation for the structural design to satisfy a required airflow rate is also examined in this paper.