What type of die steel is best for punching 5mm red copper? A viewer asked me this question during the 296th live stream.
Punching red copper tends to cause copper powder to stick to the punch. The punch must not only resist material adhesion but also have a hardness of 58 HRC; crucially, it must also have good toughness to prevent breakage. Based on these performance requirements and our experience from past successful cases, I recommend 8566 die steel.
8566 offers four times the crack resistance of high-speed steel SKH-9 and twice that of D2, with a hardness of 58–60 HRC. It primarily addresses the chipping issues that high-hardness die steels such as D2, DC53, and SKH-9 cannot resolve. Especially in applications where punches are prone to chipping—such as stainless steel stamping, sharp-corner stamping, thick-sheet stamping, and even narrow-flange stamping with minimal overlap—where conventional die steels fail to prevent chipping, 8566 provides the solution.
I recall during my last livestream—Episode 295—one of my long-time customers told me that 8566 performed exceptionally well for cold punching of red copper. Using a 16mm-diameter punch to extrude T2 copper with a hydraulic press to a depth of 20mm, the original punches made from DC53 and Cr12MoV were prone to breaking; even the best DC53 punches would break after just a few hundred punches. Now, using an 8566 punch, we’ve stamped over 10,000 products without a single breakage—the results have been excellent.
With 8566, the service life of a punch used to stamp T2 red copper to a depth of 20mm has increased from breaking after just a few hundred cycles to lasting over 10,000 cycles without breaking. Based on these figures, the service life has improved tenfold.
A 10-fold increase in punch life means that one 8566 punch is equivalent to 10 DC53 punches. The savings on punch machining costs alone are enough to purchase a large quantity of 8566 die steel, effectively making 8566 free to use.
Furthermore, while the punch life has increased tenfold, the price of 8566 is not ten times that of DC53; it’s as if you’re purchasing 8566 die steel at one-tenth the price, resulting in lower material costs.
By avoiding the need to replace 10 punches, the time saved translates to improved production efficiency. Since you don’t have to machine the punches, the operator can free up time to perform other tasks.
In essence, using 8566 for punches not only makes them effectively free to use but also extends their service life by 10 times while saving significant machining costs, achieving high efficiency, long service life, and low-cost operation.
Regarding the user’s mention of stamping 5-thick red copper, I strongly recommend 8566 anti-chipping steel. We’ve had customers use 8566 die steel to stamp 1.5mm red copper before—it withstood hundreds of thousands of stamping cycles without any issues and didn’t require edge grinding.
I want to remind you: do not use Cr12MoV or SKD11 for stamping red copper. These materials tend to attract copper powder; as one user in my 295th livestream mentioned, Cr12MoV and DC53 can even cause punch breakage. At best, DC53 can only handle a few hundred cycles. With this kind of hassle, you won’t be able to scale up production—you’ll end up trading punches for products, resulting in extremely high production costs. Choosing the right die steel will help you achieve twice the result with half the effort; otherwise, all your efforts will be in vain, and the cost of the die will increase—which is simply not worth it.
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Wu Dejian’s tool steel, the chief of staff of the user, bought everything he had used.