Abstract

Cutting precision is extremely affect by a phenomenon known as built-up edge (BUE) that occurs on tungsten carbide tools during low cutting speed of aluminum alloy. BUE is responsible for early tool breakage due to excessive material build-up from the machined part on the cutting face, leading to problems of shape irregularity and tool-tip breakage. Thus, Diamond-like Carbon was deposited and tested to verify cutting precision in aluminum alloy by using tungsten carbide tools. The characterizations of the film were: Morphology analysis through scanning electron microscopy; structural atomic analysis of chemical bond from Raman Backscatter Spectroscopy; X-ray photoelectron spectroscopy helped to identify the distribution of carbon atoms on the film surface, and the evaluation of Young's modulus and hardness using the Oliver-Pahrr method. To analyse the cutting precision, drilling tests were performed on coated/uncoated drills at two cutting speeds (340 and 430 m/min). As an evaluation parameter in the aluminum alloy, the hole diameter deviation was measured after pre determined numbers of drilling operations. Statistical comparisons between the diameter deviation as a function of the number of drilling test indicated better cutting accuracy for the DLC coated tool. The factors identified in this work, such as the reduction of the friction coefficient, and the hardness and Young's modulus of the DLC helped in the performance of the tool, mainly in the lower cutting speed.

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