Comparative Study of Cutting Insert Wear and Roughness Parameter (Ra) while turning Nimonic 90 and Hastelloy C-276 by Coated Carbide Inserts

Abstract

Abstract The present investigation aims to compare the SEM - tool wear and surface roughness (Ra) after machining while dry turning of Nimonic 90 and Hastelloy C-276 with coated cutting inserts (PVD-TiAlN, CNMG 120408 UR – WS25PT). The experiments were conducted using this parameters: cutting velocity = 118 m/min; feed = 0.111 mm/rev, cutting depth = 1 mm, machining length = 50, 100 and 200 mm. The workpiece average surface roughness parameter (Ra) data obtained while dry turning Nimonic 90 with PVD - TiAlN cutting inserts after a different cutting length (50, 100 and 200 mm) was 0.873 µm, 0.954 µm and 1.562 µm respectively. The Ra value of the Hastelloy C-276 workpiece surface after being machined for the same machining conditions was 0.758 µm, 0.936 µm and 1.709 µm. Due to increased turning length, increased Ra values were obtained in both the work materials. The flank and rake surfaces wear mechanism were analyzed using a Scanning Electron Microscope. The wear rate of PVD-TiAlN coated cutting inserts was higher while turning Nimonic 90 alloy over Hastelloy C-276 after a cutting length of 50 mm and 100 mm, but after about 200 mm machining length the tool wear was high in case of Hastelloy C-276. It also observed that with the increase in cutting length, the tool wear and roughness values were increased.