Machinability Of Polyamide 6 Under Cryogenic Cooling Conditions

Bertolini, R.; Ghiotti, A.; Bruschi, S.

Abstract Machining of polymeric materials can attain interest when the production lot does not justify the cost of molds or extrusion dies, or when the product to be manufactured requires dimensional accuracy not achievable otherwise. In this framework, the present study aims at evaluating the machinability of the polyamide 6 as a function of the cooling conditions. Two different cryogenic cooling configurations were adopted, whereas the conventional flood cooling was used as reference for sake of comparison, leading to machining conditions under very different temperature ranges. The polyamide 6 machinability was evaluated in terms of surface integrity (surface roughness, surface defects, crystallinity percentage and hardness) and chip morphology. Results show that the polyamide 6 has to be cut in a specific temperature range, namely between -20°C to 20°C, in order to get the best surface finish, namely achieving the lowest surface roughness and density of defects. In addition, the cryogenic cooling is proved to produce harder surfaces than the flood condition, but leaving unaltered the polymer crystallinity degree.