On-machine surface finishing of aluminum injection mold by sliding burnishing process with active rotary tool

Abstract

In this study, the fundamental burnishing characteristics and quality of a molded product were evaluated during the sliding burnishing process with an active rotary tool developed by the authors was applied to the on-machine surface finishing of an aluminum mold for resin injection molding. The burnishing characteristics were mainly evaluated based on the surface profile, roughness, glossiness, material composition, and residual stress. The burnishing force increased with the indentation depth of the tool, and a constant fluctuation occurred according to the tool rotation cycle. Good burnished surface roughness and glossiness were achieved when the burnishing tool was fed at the same height as the cusp recesses on the preliminary surface. High compressive residual stress existed on the subsurface during the burnishing process, compared to the machined surface and polished surface, and the compressive residual stress increased with the indentation depth of the burnishing tool. The feed direction of the burnishing tool had a significant effect on the burnished surface quality, and the quality improved when the sliding directions of the tool rotation and tool feed were the same. The mold piece obtained from the burnishing process had almost same surface roughness as that obtained from the polishing process. The molded product quality obtained for these molds was similar to the mold surface quality, and the molded product obtained from the mold fabricated through the burnishing process had the same quality with that obtained through the polishing process. Based on these results, on-machine surface finishing of the injection mold was achieved using a general machine tool through position control by applying sliding burnishing with an active rotary tool.