Mr. Yang came by again today to purchase 8566 anti-chipping steel. While this may seem like a routine task over the past two-plus years, it was actually hard-won.
I recall Mr. Yang once mentioning that when precision-stamping gears from 5mm-thick S420MC pickled sheet, he initially used DC53 steel with a hardness of 60–62. However, the teeth were prone to chipping—chipping occurred after about 5,000 pieces, with each chip measuring 6–7mm. Even imported DC53 didn’t work out. After trying various options, he found that Yuhui’s 8566 anti-chipping steel worked best. That’s why, for over two years now, Mr. Yang has been coming frequently to purchase 8566 anti-chipping steel.
This fine-tooth precision blanking die is made from 5mm-thick S420MC high-strength, low-alloy plate. Due to the small clearance in the die, the thick plate is forced into the die under high pressure, placing extremely high demands on the die steel’s resistance to chipping.
DC53 is a high-carbon, chromium-8 (Cr8) cold-work die steel with a carbon (C) content of 1.0%. It can achieve a hardness of 60–62 HRC, and while its wear resistance is adequate, its toughness is somewhat lacking. When used in such harsh operating conditions—with a fine-tooth design and a narrow clearance for precision punching of thick plates—it is prone to chipping. In fact, the current die chips after only 5,000 punches, with large chunks of 6–7 mm breaking off at a time, which confirms this issue. DC53’s performance simply does not meet the requirements for this type of fine-tooth, thick-plate precision punching die.
In contrast, 8566 is a proprietary anti-chipping steel developed by Yuhui Mold Steel, specifically designed to address mold chipping issues. 8566 offers four times the chipping resistance of high-speed steel SKH-9 and twice that of D2, with a hardness of HRC 58–60. It effectively resolves chipping problems that high-hardness mold steels such as D2, DC53, and SKH-9 cannot overcome; In particular, under severe conditions—such as stainless steel stamping, thick-sheet stamping, fine-blanking dies, sharp-corner stamping, narrow-flange stamping, and stamping where the hole diameter is smaller than the sheet thickness or the stamping ratio is less than 1:1—chipping issues that standard die steels cannot resolve are all addressed using 8566 anti-chipping steel.
When fine-blanking 5mm-thick S420MC gears, although Mr. Yang declined to disclose the exact number of punches made with 8566, his frequent purchases over the past two years indicate that he is satisfied with its service life—otherwise, he would not be repurchasing it so often.
Using 8566 die steel for punch chipping makes a world of difference. If the punches in your gear fine-blanking dies are prone to chipping, you should definitely give 8566 anti-chipping steel a try.
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Wu Dejian’s tool steel, the chief of staff of the user, bought everything he had used.