Enhancing dimensional accuracy and surface integrity by helical milling of carbon fiber reinforced polymers

Geometrical defects are one of the main problems in machining of carbon fiber reinforced polymer (CFRP) laminates Helical milling is a brand new machining process and a kind of manufacturing method that helical tool movement is added and results in better hole quality with one-time machining. In recent years, helical milling is attracting increasing attention of numerous researchers. In our study, an experimental investigation is carried out on CFRP laminates by using tungsten carbide tool. For the first time, effects of process parameters like cutting velocity and feed rate on the hole quality aspects such as hole diameter, circularity, cylindricity and surface roughness are experimentally and statistically discussed. Besides, surface morphology of the hole wall is examined. Analysis of variance (ANOVA) is carried out on hole quality parameters and their contribution rates are determined. Increasing cutting velocity improved hole diameter, circularity and cylindricity and had no significant influence on surface roughness. In addition, reduction in feed rate is suggested to have a high-quality hole in helical milling of CFRP. By statistical evaluation, results show that cutting velocity in all cases, is more effective than feed rate. Moreover, machining force is reduced in helical milling compared to conventional drilling.