When stamping 2.5-thick stainless steel, Yuhui’s 8566 die steel increased the mold’s service life by 8 times, which delighted Mr. Zhang. However, upon hearing that 8566 die steel was the same material as H13, Mr. Zhang was puzzled.
Here’s what happened: Mr. Zhang’s mold was used to stamp 2.5mm-thick stainless steel, and the product featured some narrow edge strips. Previously, when using D2 die steel, the punch would chip after just 5,000 stamping cycles. The metal shavings carried up by the chipped punch would damage the products, rendering them non-conforming. Since it was a progressive die, Mr. Zhang had to constantly repair the die and replace the punches, which caused delays and prevented production from moving forward. Furthermore, the frequent need to replace punches—which were expensive—left Mr. Zhang quite perplexed.
After Mr. Zhang approached me, I noted that since the primary failure mode of his die was chipping—and given that he was stamping 2.5-thick stainless steel, which is a hard material in the thick-sheet category—the die steel required extremely high resistance to chipping. However, he had chosen D2 die steel, which has poor resistance to chipping.
D2 is a high-carbon steel with a carbon content of 1.5 percent. It suffers from severe microstructural segregation and contains a large number of microscopic cracks invisible to the naked eye. When subjected to external impact, these cracks can cause chipping or fracturing. The fact that his dies are now chipping after only 5,000 stamping cycles clearly demonstrates that D2 is unsuitable for stamping 2-thick stainless steel. At that time, I recommended that he use 8566 die steel (anti-chipping steel).
8566 die steel is a proprietary chipping-resistant steel developed by Yuhui Mold Steel, designed primarily to address mold chipping and cracking issues. It has accumulated over a thousand case studies across 5 stamping operating conditions, 6 major material types, and 7 major application areas. The chipping resistance of 8566 die steel is four times that of high-speed steel SKH-9 and twice that of D2, with a hardness of 58–60 HRC. It is primarily designed to resolve chipping issues that high-hardness mold steels such as D2, DC53, and SKH-9 cannot address. In particular, for stainless steel stamping, sharp-corner stamping, and narrow-flange stamping—where conventional die steels fail to prevent chipping—8566 die steel has proven effective.
As our Mr. Chen noted, the performance of 8566 die steel is particularly evident when stamping 304 stainless steel; it can handle over 20,000 cuts of 3mm-thick stainless steel without any issues.
After hearing my explanation, Mr. Zhang purchased some 8566 die steel to try out. He found that punches made from 8566 die steel could stamp 40,000 products in a single run without chipping. Seeing such excellent results—with service life increasing from 5,000 to 40,000, an eightfold improvement—he wanted to further leverage the performance of 8566 die steel by applying a coating to enhance wear resistance and increase the number of stamping cycles. However, the coating manufacturer ran a spectral analysis and determined that the material was H13 die steel. This puzzled him—he didn’t believe H13 possessed such excellent performance, so how could it possibly have increased the punch’s service life by eight times? He called me to confirm.
After reviewing the photos he sent—taken with a non-destructive spectrometer—I immediately understood the problem. Non-destructive spectrometers cannot measure carbon content, and since 8566 die steel contains a very high percentage of molybdenum—a heat-resistant alloy element—the instrument mistakenly identified it as H13.
This is entirely reasonable and to be expected, because 8566 die steel is a proprietary anti-chipping steel developed by Yuhui Mold Steel. It is our company’s proprietary grade, not a national standard, and is not in the public domain; we hold the intellectual property rights to it. The manufacturers of these instruments do not have the chemical composition standards for 8566 die steel in their software, nor do they recognize this grade. Since the measured molybdenum (Mo) content was exceptionally high—and high molybdenum content is typically associated with hot-work die steels—the machine misidentified it as H13. This indicates that their instrument has not been properly calibrated, but the data is accurate. If their instrument reads 8566 die steel, then it has been tampered with or recalibrated, and the data it measures cannot be trusted.
After hearing my explanation, Mr. Zhang’s worries were put to rest. He said, “I know there are a lot of counterfeit 8566 die steel on the market, so I was hesitant to buy them. I never expected their lifespan to have increased eightfold. I think the 8566 die steel still has room to perform better—reaching 100,000 cycles shouldn’t be a problem. And I wanted to take some of the punches and have them coated to see how long they’d last. I didn’t expect the coating manufacturer to tell me they were made of H13—I just couldn’t believe it—so I came here to verify it. Now I can finally rest easy.”
The punch life has increased eightfold—the results speak for themselves—and he’s extremely satisfied. When it comes to preventing punch chipping, using 8566 die steel makes all the difference. If your punches are also experiencing chipping issues that you can’t resolve, you should definitely give 8566 die steel chipping-resistant steel a try.
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I am Wu Dejian, the “King of Mold Steel,” from Dongguan Yuhui Mold Steel. Yuhui Mold Steel is used by three Fortune 500 companies, and Kyocera has been sourcing our products for seven consecutive years. I have helped over 4,000 companies solve complex challenges related to mold material selection, manufacturing, and usage. If you’re unsure about which mold steel to choose, or if the steel you’re currently using results in short mold lifespans, or if you’re unsure which material to use, feel free to reach out to me. I’m confident I can serve as your trusted advisor in this area and help you avoid costly mistakes. Wu Dejian Mold Steel—your trusted advisor—and customers who’ve tried us keep coming back!