Effect of tool path on cutting force in end milling

Tool path generation is an important task in end milling. In the existing literature, the tool path pattern/style is determined based on geometric analysis. However, there is little analysis from the viewpoint of machining dynamics/cutting force, which is more related to the final manufacturing performance. Although there are many types of tool paths (e.g., zigzag, spiral, and ISO-scallop tool path), they can be decomposed into a number of circular tool paths with various path radii and cutting angles. Firstly, by investigating chip formation mechanism, the effect of tool path radius on uncut chip thickness is obtained. Analysis shows that tool path radius has a significant influence on uncut chip thickness, thus affecting the cutting force, especially when the tool path radius is small. Then, the effect of cutting angle on cutting force distribution is analyzed. It is found that the feed direction could vary the distribution of cutting force in X and Y direction in 3-axis end milling. Based on such analysis, the cutting force prediction model considering tool path effect is established. To validate the proposed model, various experiments have been carried out based on well-designed tool paths. The comparative results show that (1) tool path has great effect on cutting force through the tool path radius, rotation direction, and start/end point, and (2) the proposed model is capable of providing accurate cutting force prediction considering tool path effect. From a physical viewpoint, the proposed method provides huge potential in automated/intelligent tool path optimization towards better surface quality via minimizing cutting force, which significantly contributes to the state of the art in tool path generation.