Research Article

Development of micro rotary swaging tools of graded tool steel via co-spray forming

¹ Foundation Institute for Materials Science, Badgasteiner Str. 3, 28359 Bremen, Germany
² Bremen Institute for Mechanical Engineering, University of Bremen, Badgasteiner Str. 1, 28359 Bremen, Germany
³ Laboratory for Precision Machining (LFM), University of Bremen, Badgasteiner Str. 2, 28359 Bremen, Germany

^* e-mail: cscui@iwt.uni-bremen.de

Received: 30 September 2015
Accepted: 8 October 2015

Abstract

In order to meet the requirements of micro rotary swaging, the local properties of the tools should be adjusted properly with respect to abrasive and adhesive wear, compressive strength, and toughness. These properties can be optimally combined by using different materials in specific regions of the tools, with a gradual transition in between to reduce critical stresses at the interface during heat treatment and in the rotary swaging process. In this study, a newly developed co-spray forming process was used to produce graded tool material in the form of a flat product. The graded deposit was subsequently hot rolled and heat treated to achieve an optimal microstructure and advanced properties. Micro plunge rotary swaging tools with fine geometrical structures were machined from the hot rolled material. The new forming tools were successfully applied in the micro plunge rotary swaging of wires of stainless steel.