A study of internal face finishing of the cooling channel in injection mold with free abrasive grains

Abstract

This paper deals with a finishing method for the internal face of a cooling channel located in an injection mold that makes use of free abrasive grains. The injection mold is fabricated by layered manufacturing equipment using a ferrous based metal powder. When the internal pressure is loaded to the hydraulic cylinder, the solution containing the free abrasive grains is passed through the cooling channel. The internal face is then finished by the free abrasive grains. The effects of various conditions on finishing characteristics are investigated experimentally. The results showed that the internal face roughness of the cooling channel improved significantly during the first 1000s of finishing. The significant improvement achieved during the initial stages of finishing is due to the removal of the aforementioned unstable powders. Free abrasive grains are employed to remove the unstable powder on the internal face rather than to polish the alloyed face. The high-speed flow of the free abrasive grains results in an increase in their kinetic energy, thereby increasing the force with which they collide with the internal face and resulting in an improvement of the surface roughness. The internal face finishing was effective for the improvement of the thermophysical properties in the cooling channel.