Machining Dynamics in Milling Processes

Abstract

The milling process is distinguished by a rotating tool with one or more teeth that removes material while travelling along various axes with respect to the workpiece. The engagement of each tooth with the workpiece is discontinuous in the milling process different to the turning process. As a tooth engages the workpiece, it receives a shock followed by a varying cutting force. The cyclic shock and variation of the cutting force induces vibrations between the tool and workpiece. It can also provide the necessary energy to excite a natural mode of vibration in any part of the machining system. These vibrations should be minimized because they can, and frequently do, degrade machining accuracy and surface finish. Moreover, under unfavourable conditions they may become unstable, leading to chatter, which can cause accelerated tool wear and breakage, accelerated machine wear, and even damage to the machine and part. For high speed machining and especially high speed milling, unstable vibration or chatter is a major factor limiting production rate.