Question from a viewer during the 300th live stream: What type of die steel is best for punching 3mm-thick aluminum?
When punching aluminum, many die failures are caused by aluminum shavings sticking to the die, resulting in burrs on the product. However, many people mistakenly believe this is due to insufficient hardness or poor wear resistance of the die steel. This leads to incorrect material selection—even when using high-hardness die steel, the die is still prone to aluminum shavings sticking to it, and the product still tends to develop burrs. In this case, we need to choose a mold steel that resists material adhesion. In fact, a hardness of 58 HRC is sufficient; instead, we should prioritize non-stick performance.
When stamping aluminum sheets, if you choose Cr12MoV, SKD11, D2, or DC53—these high-carbon steels with very high carbon content—their microstructure will contain a large number of microcracks after heat treatment. Furthermore, since today’s mold steels prioritize extremely low prices, their smelting quality is very poor, with severe segregation and a large number of microscopic cracks invisible to the naked eye. These microscopic cracks easily cause adhesive wear when punching aluminum material. This is also a source of confusion for many people.
When punching 3mm-thick aluminum—a relatively thick material—the high friction during the punching process causes the workpiece to heat up easily, making the die even more prone to aluminum shavings sticking to it. Your die steel must not only be of high metallurgical quality and free of microcracks but also have a high thermal conductivity to ensure rapid heat dissipation from the die. Based on the performance requirements for dies and past case experience, I recommend 85666 anti-chipping steel.
During the 299th live stream, a viewer commented: “8566 doesn’t stick to aluminum, and there’s very little aluminum shavings—it’s excellent.”
There’s also Mr. Bao from Dongguan, who was performing 45° angled punching on 4mm aluminum sheets. His original punches were made of DC53 and SKH-9, used in a continuous die with a punching speed of 100. Working 10 hours a day, he had to replace at least one punch daily—sometimes even two. The punches would either get clogged with aluminum shavings or chip off, which was very frustrating.
After he contacted me, I recommended he use 8566 chipping-resistant steel. A month later, he told me that with the 8566 die steel, his punching speed had increased from 100 to 200, and after more than 10 days of operation, there were no issues with aluminum shavings sticking to the punch, nor was there any die wear—which amazed even the industry leaders.
Increasing the punching speed from 100 to 200 is equivalent to getting two days’ worth of work done in one day—that’s effectively doubling efficiency.
Previously, he had to replace at least one punch per day, but now he’s been punching for over 10 days without needing a replacement, which means the die’s service life has increased by 15 times.
With efficiency doubled and service life increased by more than 10 times, anyone would be thrilled. It’s no wonder the industry leader was so impressed. I’m sure even the industry leader has never seen such an amazing material.
Then there’s our Mr. Qi, who was stamping 2mm-thick aluminum. His punch was only 2.01 wide, and he was using DC53. Because the punch was relatively narrow and long, it was prone to chipping. But after switching to Yuhui 8566 anti-chipping steel, he stamped 1 million products without ever having to sharpen the cutting edge.
The netizen asked what die steel is best for stamping 3mm-thick aluminum. I think whether you’re stamping 2mm, 3mm, or 4mm—thicker aluminum sheets—using 8566 chipping-resistant steel is the safest choice.
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Wu Dejian’s tool steel, the chief of staff of the user, bought everything he had used.