ANALYSIS OF THERMAL EXPANSION AND MICRO-DELAMINATION PHENOMENON OF CUTTING TOOL THIN SURFACE COATINGS IN HIGH-SPEED DRY MACHINING

ABSTRACT High-speed machining (HSM) is one of the commonly implemented recent machining technologies in industrial manufacturing operations that enables higher efficiency and accuracy as reducing production cost and machining cycle times depending on the specific manufacturing operation requirements and demands. Particularly dry machining is characterised with severe level of temperature and heat generation enters into cutting tools rather than machining with cutting liquid, which leads to detrimental effects on tool lifespan resulting in premature cutting tool failure or tool damages. In order to overcome this problem, cutting tool thin surface coatings are applied to reduce the amount of heat transferring into cutting tool by enhancing the tribological conditions and wear resistance of cutting tools. However, as a result of the coefficient of thermal expansion (CTE) mismatching of coating layer materials, delamination phenomenon can be observed in coating structures during machining. As outcomes of the study based on the results obtained, total dimensional thermal expansion and micro-delamination of the most appropriate optimised 3-layered coating structure were relatively decreased and the necessity of the thermal expansion capacity consideration in coating implementations was revealed for related Finite Element Analysis (FEA) simulations and coating structure designs