Reduction of Minimum Cutting Thickness of Titanium Alloys in Micro Cutting by a Magnetic Field Assistance

Abstract

Ultra-precision diamond cutting (UPDC) is a promising machining technology to generate precise components with optical grade surface. However, a tool rake angle turns to be negative when the tool radius is significantly larger than cutting depth during UPDC. The resulted plowing motion, which is the well-known size effect, causes undeformed and uncut materials remaining on the machined surface and thus affects the surface integrity of final components. In this study, the tribology behavior of tool/workpiece was altered in order to resolve the problematic size effect. A magnetic field was superimposed into titanium alloys during UPDC to increase the friction coefficient at the tool/workpiece interface in order to minimize the size effect and reduce minimum chip thickness (MCT) in UPDC. The experimental results showed the friction coefficient at the tool/workpiece interface increased under the magnetic field influence and a better surface quality was achieved in the presence of magnetic field. MCT of titanium alloys was reduced to 1μm by utilizing the proposed machining technology which the reduction percentage reached to 50%. A lower MCT value means the feasibility of machining under smaller depth of cut and thus enhances the existing precise level of components fabricated in ultra-precision machining.