In recent years, there has been an increasing demand for thin-walled titanium components and thus for economic manufacturing technologies, e.g. in the aviation industry. During the machining of thin-walled titanium parts, component distortions may occur. These are caused by high specific cutting forces in combination with the mechanical properties of titanium, which may induce residual stresses and limits the productivity of machining processes today. Furthermore, the distortions may be caused by the release of residual stresses from the semi-finished products – especially when machining additively manufactured parts.
In order to reverse these undesirable deformations, a defined deep rolling process may be used. Deep rolling is a mechanical surface treatment process that is typically employed to positively influence the near surface area of a component in order to improve its fatigue strength. In this process, a rolling ball tool is used to apply a force on the workpiece surface thereby introducing compressive internal stresses into the surface layer as well as smoothing the surface.
The publication shows that defined deformations of thin-walled titanium components can be created by proper choice of deep rolling process parameters. For this purpose, a hydrostatic tool with a rolling ball was used to treat the upper side of the sheets along straight lines. The number of passes, the offset between subsequent passes, the sheet thickness, the processing pressure and the ball diameter of the tool were varied. The resulting deformations are quantified by means of tactile measurement. Hence, post-processing by deep rolling shows a high potential for avoiding cost-intensive scrap of titanium-parts.