Investigation of the effect of different cutting parameters on chip formation of low-lead brass with experiments and simulations

Abstract

Poor chip breakage causes problems in machining of low-lead brass. To improve chip breakage, finite element model simulations were implemented in cutting tool design. Finite element model simulations enable high number of experiments that would be expensive and slow to perform by conventional cutting tests. Compression tests and cutting experiments under different temperatures and strain rates were performed for lead-free brass, to acquire material parameters for the finite element model. It was observed that the coupled effect of thermal softening and rate sensitivity of the material was difficult to take into account with the existing material model. Furthermore, it was found that there are no reported material models that can take rate sensitivity–temperature coupling into account. This was counteracted by fitting the model with least square method to the stress–strain data at the cutting temperature, although this causes error in simulations with temperatures higher or lower than the supposed cutting temperature. Nevertheless, the simulated results proved accurate enough to model the chip breakage. Based on the simulations and experiments, the use of a positive rake angle, high cutting speed and low cutting feed rate improve chip breakage from continuous chip to a chip of average length of 4 mm.