Title: Investigations into the influence of tool helix angle during end milling of open straight and curved thin-wall parts
Authors: Gururaj Bolar; Shrikrishna N. Joshi
Addresses: Department of Mechanical and Manufacturing Engineering, Manipal Institute of Technology, Manipal Academy of Higher Education, Manipal, 576-104, Karnataka, India ' Department of Mechanical Engineering, Indian Institute of Technology Guwahati, Guwahati, 781-039, Assam, India
Abstract: In this paper, the influence of cutting tool helix angle on performance parameters viz., milling force, part deflection, surface finish, chip morphology and micro-hardness considering open straight and curvilinear thin-walled parts is analysed. It was found that end mills with helix angle of 45° and 55° helped in achieving good surface finish and form accuracy while machining thin-wall parts. During machining, parts having concave geometry due to its inherent rigidity, generated higher milling force. But the wall deflection and form error was relatively lower in comparison with the straight wall thereby resulting in better surface finish. Also, formation of built-up-edge (BUE) at the cutting edge of end mills having 35° helix was noted which aided in surface defects. Back surface of the chips machined using 35° tools showed prominent lamella like structures but tools having higher helix angles were found to produce relatively lamella free surface.
Keywords: thin-wall; helix angle; chip morphology; micro hardness; milling force; surface roughness; built-up-edge; BUE; finite element simulation.
International Journal of Machining and Machinability of Materials, 2020 Vol.22 No.3/4, pp.212 - 232
Received: 22 Nov 2018
Accepted: 20 Apr 2019
Published online: 01 May 2020 *