Machinability of Thermo-Plastic Carbon Fiber Reinforced Plastic in Inclined Planetary Motion Milling

The study deals with an improved method of milling thermo-plastic CFRP with a radius end mill. The authors use inclined planetary milling to carry out a fine CFRP boring technique. The inclined planetary motion milling consists of the two independent spindle motions of tool rotation and revolution. The eccentricity of the tool rotation axis is realized by a few degrees of inclination from the revolution axis. The movement of eccentric mechanism can be reduced by comparing it with that of orbital drilling. The inclined planetary motion milling reduces inertial vibration and decreases cutting force. Owing to the geometrical cutting principle, material delamination and burrs can be decreased. Thermo-plastic CFRP has recently been under development as an alternative structural material for the next generation of automobiles and in response to demands for bored fastening holes. The shape of the cutting edge of the ball end mill is suitable for the inclined planetary milling, as revealed by results of past experiments done on thermo-set CFRP. However, the ball end mill has left burrs and melted matrix on the exit side in the case of thermo-plastic CFRP. The radius end mill has the advantage over the ball end mill in terms of finishing fine boring. Based on the consideration of the schematic model and experiments using the Taguchi method, the improved milling conditions are examined.