Design for quality approach to improve surface roughness in milling operations

Tooling related malfunction is of particular concern, since tooling condition can cause loss of dimensional part accuracy and loss of the required surface finish. Out of specifications surface parameters will often be confined to less than quality making features and hence affect manufacturability. There is an eminent need for a methodology that enables process designers to evaluate and improve the quality manufacturability of the milling process before machining. This paper describes a methodology of design for quality manufacturability that enables product designers to evaluate, quantify and improve surface roughness in the design stage for milling operations. Different experiments have been conducted to measure cutting forces and surface roughness parameters under dry cutting conditions. The relationships between different operating parameters to the cutting force and surface roughness parameters were examined through extensive experimental work. Different relationships have been developed between five surface roughness parameters and three operating parameters. Further analysis has been conducted on the cutting force pattern: seasonal pattern, nonlinear trend and peak. The results generated from the study are very important for the parameters' design of manufacturability for the milling operation. The basis for the design for quality is a set of common classes of quality defects (errors), and a set of factors that influence the occurrence of the less quality. The concept of quality errors and the derivation of the index matrix are presented.