Dry Machining Performance of AA7075-T6 Alloy Using Uncoated Carbide and MT-CVD TiCN-Al 2 O 3 -Coated Carbide Inserts
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RESEARCH ARTICLE-MECHANICAL ENGINEERING
Dry Machining Performance of AA7075-T6 Alloy Using Uncoated Carbide and MT-CVD TiCN-Al2 O3 -Coated Carbide Inserts Sarthak Prasad Sahoo1 · Saurav Datta1 Received: 22 November 2019 / Accepted: 17 September 2020 © King Fahd University of Petroleum & Minerals 2020
Abstract The present study examines dry machining performance of AA7075 T6 alloy using uncoated and MT-CVD TiCN–Al2 O3 coated carbide inserts. Machining performance is assessed with regard to tangential cutting force, tool tip temperature and depth of flank wear. The performance of coated tool is compared to that of uncoated insert. In addition, different modes of tool wear and chip morphology are studied in detail. It is experienced that coated tool causes lower tool tip temperature and lesser flank wear than untreated counterpart. Apart from abrasion, adhesion and built-up layer formation; attrition wear is distinctly visible in case of uncoated tool. On the contrary, in addition to common wear modes, coated tool also experiences diffusion wear. Keywords Dry machining · AA7075 T6 alloy · Coated carbide · Flank wear · Tool wear · Chip morphology
1 Background Light metal alloys have low density, high stiffness and high strength-to-weight ratio. These alloys are of great importance in engineering industries for the construction of transportation equipment, aircraft parts, aerospace, military and missile applications [1]. Aluminum and its alloys occupy the second position, next to steels, in the field of structural materials applications [2]. Aluminum alloys possess good machinability as compared to ferrous alloys; however, high cutting forces, disappointing surface quality and difficulty in chip control were reported due to ductility of these alloys [3]. Since 1930, 2XXX, 6XXX and 7XXX series aluminum alloys were recommended for use in aircraft industry due to their high strength-to-weight ratio [4]. However, 7050-T7451 alloy is used for aircraft structures [5], while AA-7075-T6 is used for producing gears, fittings and shafts [6]. Therefore, it is very vital to have proper knowledge and in-depth understanding on machining aspects of this low-density material. In metal cutting principles, Wright and Trent [3] conferred that machining of ductile materials like aluminum was prone to large tool–chip contact area and high chip thickness
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Saurav Datta [email protected] Department of Mechanical Engineering, National Institute of Technology, Rourkela, Odisha 769008, India
ratio which lead to high cutting force, high power consumption and enormous heat generation at the deformation zones. Kelly and Cotterell [7] reported microstructural changes, increased tool wear, residual stresses and sticking tendency of workpiece material over tool edges, during machining of aluminum alloy. High ductility of the alloy resulted in longer chips and inter-atomic diffusion between work and tool coating materials [8]. Conventional dry machining is a necessary practice as it corresponds to low cost of machining, less environmental iss
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