Research of Co loss of cemented carbides progressive die in high-speed stamping

Die wear, especial progressive die wear is a major concern in the stamping industry in respect that it brings many problems, including shortened service life, wasted energy, increased production cost and lowered production efficiency. Alleviating die wear can increase the die inserts’ service life and is helpful to avoid frequent replacement of worn inserts and hence reducing the corresponding costs. WC-Co cemented carbide has good wear resistance and flexibility and is the most common used material for making progressive dies, but the die wear is still a prominent problem, especially in high-speed stamping. Some researches have shown that the appropriate content and even distribution of Co phase are very important to the performance of WC-Co cemented carbides. This paper is conducted to investigate the wear status and mechanism of WC-Co cemented carbides progressive die in high speed stamping. At first, the high-speed stamping test for WC-Co cemented carbides progressive die is carried out to get worn samples. Then the tool microscope is used to observe the surface pattern of the worn cutting edge of the tools. The scanning electron microscope is used to analysis the difference of microstructure of cutting edge of the progressive die both in unworn region and in worn region. The energy spectrometer is used to detect the relative percentage composition of Co and W elements on the cutting edge surface of the progressive die. The results showed that :(1)The macro and micro structure of cemented carbides progressive die change after long time and high speed stamping. (2) There are some small macro pits on the worn cutting edge. (3) The percentage composition of Co element in the worn region decreases. Finally, the Skeleton Theory and Composite Reinforcing Theory are used to analysis the effect of the Co loss. The research shows that the Co loss of cemented carbides in high-speed stamping is an important factor affecting the wearing and property of progressive die.