Flexible tool system for cold forging of micro-components

C. P-Withen (a), J. R. Marstrand (a), M. Arentoft (b), N. A. Paldan (b)
a Department of Manufacturing Engineering and Management, Technical University of Denmark, Produktionstorvet, Building 427, DK- 2800 Kgs. Lyngby, Denmark
b Institute for Product Development, Produktionstorvet, Building 425, DK- 2800 Kgs. Lyngby, Denmark

Abstract

The advantages of cold forging micro-components are the same as for conventional cold forging, namely the high production rate and the low material waste. To achieve this, a flexible tool system for cold forging of micro-components has been developed. When transferring the technique of cold forging from macro- to micro-scale, size effect and change in friction are conditions that have to be considered. Furthermore the precision of the tool system is crucial owing to the low tolerances on the dimensions of micro-components.

The tool system is designed for the eight basic cold forging processes with some replaceable process dependent parts. Furthermore it is possible to replace critical parts to reduce expenses if tool breakdown occurs. The system is tested by forging of an industrial component. The tool system is produced by micro-EDM and high precision machining.

The test of the final tool system shows that it can be used to cold forge micro-components. An Ø0.8mm rod is extruded 0.9mm to Ø0.3mm in an Ag97Cu3 alloy. The geometry of the cold forged component is close to the specified geometry. This indicates that the component can be cold forged with a few adjustments of the die and punch geometries. The ejection of the cold forged component proved difficult and a slight bend of the extruded part occurred.