Abrasive Particle Generation in Dry Rotary Swaging

Rotary swaging is an incremental bulk metal forming process for the manufacture of cylindrical lightweight components. Whilst conventional rotary swaging is still carried under the intense use of lubricants to provide desired work piece quality and to avoid forming die wear, recent scientific work focuses on the design of a dry process layout. Novel functionalized rotary swaging dies were introduced, exhibiting both diamond like carbon (DLC) hard coated and structured surfaces to encounter complex and opposing tribological requirements when dry machining. Such dies were successfully applied to infeed rotary swaging experiments machining steel 1.0038 and aluminum 3.3206 tubes. Although primary targets were achieved, the dry rotary swaging process is subject to an increased abrasive particle generation from the work piece material and accumulation of such particles in the forming zone. Abrasive particles provoke a loss of work piece quality and ultimately lead to a clogging of the swaging unit, associated with a significant earlier termination of the forming process. This work presents the investigation of the particle generation when dry rotary swaging with functionalized forming dies in dependence on the work piece material and the process parameter feed velocity. Subsequently, improvements of the die s design are discussed which are to reduce the generation of abrasive particles and conveying the particles from the swaging unit, indispensable for the robust layout of dry rotary swaging processes.