Surface texture characterization of alpha-beta titanium alloy (Ti6Al4V) after hydrostatic burnishing

Rzeszow University of Technology, The Faculty of Mechanical Engineering and Aeronautics, al. Powstancow Warszawy 12, 35-959 Rzeszow, Poland

^* Corresponding author:s.swirad@prz.edu.pl

Abstract

The ball burnishing process with hydrostatic tools is very economical finishing process for various types of machine parts. This process reduces the height of surface unevenness, introduces compressive stresses at high depth (approx. 1 mm) and increase the hardness of the surface layer. The paper presents effect of the ball burnishing process parameters with hydrostatic tools on the surface structure geometry of titanium alloy. This shows how the surface roughness can be reduced after preceding operation by the ball burnishing process. This process changes the surface stereometrics of the previously milled surface. Burnishing with hydrostatic tools can be easily and effectively used either on conventional or on CNC machines. The Ecoroll burnishing system used in this research consists of a high-pressure hydraulic pump (model 4.0 HGP) and the 6 mm diameter burnishing tool both connected via high-pressure hoses. The burnishing tool is based on a hydrostatics principle; the key element is a 6mm ball made of ceramics. The input process parameters considered in the paper included: burnishing rate, applied pressure and line to line pitch. It also showed a positive effect of hydrostatics burnishing on roughness and geometric structure of the surface. In most cases, the result is anisotropic surface, reduced roughness, reduced amplitude values of parameters such as: Sa, Sz. The biggest impact on the value of indicators of geometric structure comes from pressure, the smaller (but still significant) impact results from a tool speed and line to line pitch