Grey relational analysis for impact factors of micro-milling surface roughness

Surface roughness is the most important index to evaluate micro-milling process. Surface roughness of the machined parts in the micro-milling process is mainly influenced by four cutting parameters (namely extended length of the micro-milling cutter, spindle speed, feed per tooth and cutting depth in the axial direction). The influence degree of the four parameters on surface roughness is not the same. It is of utmost important to learn the relational degree between each cutting parameter and surface roughness for accurately controlling surface roughness of the machined parts and efficiently guiding the practical machining process of the parts. Grey relational analysis is used to obtain the relational degree between each cutting parameter and surface roughness of the micro-milling parts. Through sample analysis, the feed per tooth fz has the most influence on surface roughness of the machined micro-milling parts, the relational degree between the feed per tooth fz and surface roughness Ra is 0.7688, while the extended length of the micro-milling cutter L has the least influence on surface roughness of the machined micro-milling parts, the relational degree between the extended length of the micro-milling cutter L and surface roughness Ra is 0.6054. In the practical micro-milling process, the four main cutting parameters may be reasonably chosen to accurately control surface roughness of the machined parts depending on the results of grey relational analysis.