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Effects of heat treatments on the on-line service life of a press die manufactured by W-EDM are studied. In this work, four manufacturing processes for a press die are considered: (1) milling and then grinding, (2) wire-cut electric discharge machining (W-EDM), (3) low temperature heat treatment after W-EDM, and (4) high temperature heat treatment after W-EDM. On-line punching experiments for an automobile part of BL646-chain are performed. The amount of wear of the die and punch, roll-over and burnish depth in the punched chain are measured every 1,000 strokes. Overall productivities are carefully compared. Finally, it is concluded that heat treatment after W-EDM for a press die can enhance its on-line service life. Especially, high temperature heat treatment after W-EDM is very attractive as a fast and cheap manufacturing method for a press die.

This paper is concerned with development of a process map for sequential compression-backward extrusion of bulk AZ31 Mg alloy at the warm temperatures. In experiments, metal flows and crack initiations are carefully investigated and formability is examined systematically for various forming conditions such as forming temperature, punch speed, and a gap between a specimen and die. Then, a process map for the sequential compression-backward extrusion of bulk AZ31 Mg alloy at the warm temperature is proposed. In order to further understand deformation behaviors and damage evolution during warm forming process, thermo mechanical finite element analyses coupled with damage evolutions are carried out. In general, finite element predictions support experimental observation. Finally, it is concluded that the process map, proposed for the sequential compression-backward extrusion of AZ31 Mg alloy, is valid.