Investigation Of The Burnishing Machined Surface Of Titanium Alloy

Titanium alloy with a low density, high strength, outstanding corrosion resistance capacity, and fine thermal performance, has been widely used in numerous areas. However, titanium alloy is also known as difficult to cut material. Due to its difficult to cut characteristic, the productivity in traditional machining process of titanium alloy is limited to a low level, and the surface integrity of machined parts are difficult to ensure. For the purpose of enhancing the surface property of machined titanium parts, a separate finishing process known as surface treatment is suggested to conduct with the machined parts. Burnishing is a no chip process that applies a sufficient force to produce plastic deformation of a surface layer, in which a roller or a ball pushes surface materials from the peaks into the valleys thus result in better surface integrity of the machined parts. Burnishing process a very effective surface enhancement method which decrease the surface roughness, improve hardness and introduce compression stress to the burnished surface.In this paper, a new tool for a combined machining and mechanical plastic deformation is described. This combined tool could effectively improve surface integrity of machined parts, increase productivity and reduce manufacturing production period. The operating principle of burnishing-cutting technology is discussed in detail, and machining tests with titanium alloy TC4 using this combined tool were conducted. The influence of burnishing-cutting parameters such as burnishing-cutting velocity, feed rate, burnishing-cutting depth and the spring force on hardness, surface roughness, residual stress distribution and microstructure were investigated. The 2D thermomechanical model of burnishing process is established by adopting the finite element analysis software-Deform 2D. The effect of the burnishing parameters such as feed rate, burnishing force and the size of the burnishing ball on the value of effective strain rate, residual stress, and the depth of the plastic deformed material has been fully studied.