Chip morphology and forces in end milling of elastomers

This paper describes chip morphology and forces in end milling of elastomers. A classification system that identifies elastomer chips based on their size and morphology is described. Optical pictures and Scanning Electron Microscopy (SEM) micrographs were used to examine and classify chips. A four-step examination procedure is developed to specify seven types of chips. Serrated chip formation with apparent adiabatic shear bands was observed for one end milling condition. The low thermal conductivity of elastomer is a possible cause for the observed shear band formation. Another type of serrated chip was found with surface wavy marks due to vibration of the workpiece. End milling force components were also recorded and analyzed. It was found that end milling of solid carbon dioxide cooled elastomers generated higher forces than the room temperature workpiece. A correlation of the maximum uncut chip thickness on averaged peak cutting force components is identified for different spindle speeds. This has indicated the potential for modeling elastomer machining processes.