A word of advice to those making drawing dies: stop using Cr12MoV for drawing dies. It will inevitably cause material adhesion and stringing—there’s no fixing it.
This afternoon, I received an inquiry from Mr. Liu regarding the drawing of 0.35mm-thick cold-rolled sheet. He is currently using Cr12MoV, and a small die core is sticking to the material, which increases friction. After polishing, the issue seems to resolve, but the die sticks again after 300 products. What is the cause?
The biggest concern with drawing dies is material sticking and stringing. Therefore, when selecting drawing dies, non-stick properties should be the top priority, followed by wear resistance. Cr12MoV is a high-carbon cold-work tool steel with a carbon content of 1.5%. It suffers from severe microstructural segregation and contains numerous microscopic cracks invisible to the naked eye. When this steel comes into contact with iron during the drawing process, material adhesion and stringing occur—a problem that cannot be resolved; the only solution is to switch to a different tool steel.
The fact that the die sticks after just 300 products is sufficient proof that Cr12MoV is unsuitable for drawing dies. Having to polish a die after only 300 products—especially one that was painstakingly machined—makes production inefficient. While this die steel is cheap, the hassle it causes is unbearable. I also advise against applying a coating; it won’t solve the problem and will only waste more money.
For die steel used in stretching iron parts, you must use at least 6077 wear-resistant steel.
6077 is an electroslag steel with high-quality smelting and low impurity content. Die steel with low impurities achieves a good mirror finish, which is ideal for stretching dies; Additionally, as a six-sided forged steel (three forging and three drawing processes), it features excellent microstructural uniformity and minimal micro-cracks. This makes it less prone to sticking or stringing during drawing operations. With a hardness of HRC 60–63, it offers sufficient wear resistance and three times the fracture resistance of chromium steel, ensuring the die won’t crack. There are already successful case studies of using 6077 wear-resistant steel for drawing dies with iron materials.
Mr. Tan said that the 6077 wear-resistant steel he bought last time worked quite well. I use it to draw 0.7mm galvanized sheet metal into motor housings with a 30mm draw height. I’ve already produced 3 million units, and I haven’t received a single complaint from customers. Before, when I used DC53, the dies would start showing wire marks after just a few products, and I’d get scolded by customers. Now, with 6077 wear-resistant steel, I can make 3 million products, and I’m completely satisfied. I run a mold factory—as long as customers don’t complain, I’m happy.
Mr. Liu’s experience—where the die stuck after just 300 products—reminds me once again to advise everyone: don’t use Cr12MoV for deep-drawing dies. It’s a complete waste of money.
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Wu Dejian’s tool steel, the chief of staff of the user, bought everything he had used.