Dry rotary swaging–approaches for lubricant free process design

Abstract

Rotary swaging is an incremental cold forming process and allows for the cost effective manufacture of cylindrical light weight components such as rods or hollow shafts. The process has a widespread use particularly in the automotive industry for example for the manufacture of axles and steering spindles. Besides the generation of desired geometries, rotary swaging offers the advantage of improved work piece material properties due to strain hardening and furthermore the generation of variable wall thicknesses for hollow shafts, and therefore an optimal use of material resources. Nowadays rotary swaging is carried out under the use of extensive amounts of lubricant. Main functions of the lubricant are the cooling of work piece and tools, washing out of wear particles from the forming zone and process lubrication in general. Before further processing, remaining lubricant mandatorily needs to be cleaned off the work piece, increasing the costs per unit significantly. Thus, an enhancement of rotary swaging towards a lubricant free process, i.e. a dry rotary swaging, is seen to be highly innovative, both under economic and ecological aspects. However, a lubricant free process design exhibits considerably modified frictional conditions, compared to a conventional process layout. This leads to changes in the power.