Studies to Improve the Machined Surface Texture in Micro-Milling Process

An experimental investigation on the reasons of surface texture, and the improvements of this phenomenon by flat surface micro-milling was conducted in this study. After rough machining, marks on the surface caused by scallop height, can be eliminated by using small pitch of tool path. But some slight textures on the surface still remain. By impact test and frequency domain analysis, it was found that the reasons of surface textures were little related with dynamic characteristics of machine tool structure and tool runout. Brass and pure nickel was machined in this study. Surface textures can be effectively eliminated when feed raises to 0.4 and 0.8μm/flute in brass and pure nickel machining, respectively. The reason of textures is that the partial material was plowed and elastic deformation occurred. Hence the material was not able to remove by cutting tool in a low feed. But unpreventablely, raising feed causes bad surface roughness. Adding water base fluid during the machining process can obtain better surface roughness whether the feed is high or not, even in a very low feed which the condition is good for the surface texture. According to the result, the feed of 0.16μm/flute is adopted in brass machining, and the good surface roughness Ra, which is only 0.026μm, can be obtained without appearance of surface texture.