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RESEARCH PRODUCT

Tool Failure in Sequential Cutting of two Different Materials

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In this paper the authors show that the premature tool breakage, characteristic of interrupted cutting, can be enhanced in sequential cutting of two materials having different mechanical and chemical properties. The results of experimental investigations carried out in turning pieces consisting of medium carbon steel and aluminium alloy show that the time to failure is significatively lower than that occurring in machining only one of the two materials; moreover the morphology of the damage depends by the cutting order. Working with the sequence steel-Al alloy welding phenomena caused by strong deoxidation due to the latter material are observed; these phenomena cause the early development of a “transverse crack” that is the starting point of the tool damage and of the subsequent fracture. Cutting the sequence Al-steel it was found a sudden fracture of the tool, sometime preceeded by chipping and cracks. In any case a more quick fracture than in the interrupted cutting of the steel alone was observed.