The 3-D characterisation of the surface topography of the ballizing process

Engineering surfaces are produced by a large number of manufacturing processes and once the processing is complete they are left with a surface texture which reflects the machining operation. Boring, turning, milling, grinding, lapping and honing are typical machining process, whilst roller burnishing and ballizing are typical of processes where improved surface finish as well as modified surface properties are required. These latter two processes, which have been in common usage for many years, have advantages which have not yet been fully explored. This includes the ability to deliberately impart negative residual stresses into the surface which are advantageous in improving the functional life of often stressed components as well as improved surface texture. The main purpose of this paper is to investigate the trends of roughness and residual stress related to the parameters of the ballizing process. This paper uses the 3-D surface evaluation techniques to characterise the ballized (engineered) surface and uses the ring cut-off method to calculate the residual stress on its circumference. This experimental methodology and analysis are used to show that: 1) The wall thickness of the ballized component and the interference amount are significant causes of roughness and residual stress. 2) The speed of the ball (velocity) going through the holes has a little effect on the roughness and residual stress.