Study of the lateral pass width for conventional and ultrasonic vibrations- assisted ball burnishing on Ti-6Al-4V specimens

Ball burnishing is a technological finishing process based on plastic deformation of the objective surface by means of a hard ball gliding over it. Along with its easiness of application, possible on the same machine where machining was performed [1], burnishing is a comprehensive process able to achieve surface roughness improvements, and compressive residual stresses up to deep layers of the material [2]. Burnishing results have proved to be depending of a proper selection of parameters, which must be correctly controlled during the process. That is the case of burnishing force or the number of passes [3]. Among these parameters, the lateral pass width has proved to be influential on the surface roughness results, due to the behavior that most materials show when being plastically deformed. In effect, the applied force makes the material to flow to the borders of the burnishing imprint, giving way to a pile-up effect. This paper deals with indentation experiments on Ti-6Al-4V to deepen in the burnishing process of this material. Single burnishing imprints are geometrically characterized combining different levels of force, number of passes, and comparing the conventional process with that assisted with vibrations. An optimal lateral pass width is thus determined, and technological recommendations are made for future applications of the process.