Chatter in Horizontal Milling

An analytical and experimental investigation into the chatter behaviour of a horizontal milling machine is described in this paper. The experimental results were used to check the basic assumptions involved in the analysis.

The machine structure and the cutting force characteristics of the workpiece material were initially tested separately. The vibration behaviour during machining was then investigated for a range of machining conditions. These included different values of cutter speed, workpiece width, depth of cut and number of cutter teeth, different directions of cutter rotation, and plain and climb milling. The results are presented in the form of stability charts, describing conditions when chatter was present or absent.

Chatter was found to be of the regenerative type, occurring in bands of cutter speed. For all conditions tested, the machining stability defined by the envelope of the chatter bands improved as cutting speed was reduced.

The dependence of the chatter bands on cutter speed, the chatter frequency, and the qualitative changes in the chatter-free machining capacity were predicted successfully at all but low speeds. Quantitatively, the chatter-free machining capacity was predicted to be slightly less than half that found by experiment.

The conventional assumptions for dynamic cutting force characteristics were shown to be in error. More accurate assumptions based on recent fundamental work only partly explained experimental observations, indicating that an additional, and as yet unstudied, dynamic force component exists.