Efficient Analysis of CFRP Cutting Force and Chip Formation Based on Cutting Force Models Under Various Cutting Conditions

The cutting characteristics of unidirectional carbon fiber-reinforced plastic (CFRP) during zig-zag milling, which is the most used milling tool path in the industry, were analyzed. Cutting force and chip formation are the most useful indicators of cutting performance. Here, cutting force and chip formation were analyzed in up- and down-milling, then compared with those parameters in zig-zag milling. CFRP cutting force models for up- and down-milling were used for analysis of cutting force. Chip formations were predicted via simulations of fiber cutting angle. This simulation-based study overcame various experimental limitations regarding CFRP cutting force. The specific cutting forces of various fiber cutting angles were derived from cutting experiments involving unidirectional CFRP. The specific cutting forces decreased with increasing chip thickness. These results are similar to the size effect observed in metal machining. Cutting force analysis was performed with a focus on change in feed direction and rate of radial immersion. In zig-zag milling, the optimal feed direction rapidly changed at a radial immersion of 30%. At a radial immersion of 75%, the difference in cutting force related to the change in the feed direction was large. Type I (delamination-type) chip formation was dominant in the optimal feed direction because specific cutting force was lower in the Type I section than in regions of other chip formation types.