Not only will “four-cut” mold steel fail to solve your mold chipping problem, but it will also leave you unsure of where the problem lies and how to optimize your mold. Buying “four-cut” mold steel is a recipe for disaster.
Today I received an inquiry regarding cold extrusion of red copper. The client had tried second-grade 8566, H13, and second-grade LG, but in all cases, the dies would flake off in large pieces after producing 3,000–5,000 parts. Even before reaching that count, copper would seep into the R-corners of the die. The seepage kept getting worse and worse until it eventually caused the die to split open, with the entire section flaking off.
He is cold extruding T2 red copper to produce a type of connector. He has already tried the low-hardness H13, the high-toughness LG die steel, and the high-hardness 8566 chipping-resistant steel, but in all cases, copper powder begins to seep in after 3,000–5,000 cycles, eventually causing the die to split open and the entire section to peel off. He is now at a loss on how to optimize the die and is feeling quite frustrated.
However, in my 299th session, a netizen asked me: “LG is the nemesis of red copper. Cold extrusion of red copper with LG doesn’t wear out the mold at all. The original mold could only handle 5,000–10,000 cycles, but now with LG, it can handle 50,000 cycles without breaking. It’s made things so much easier for me.”
This customer specializes in cold-extruding copper rods. He used to use LD for his dies, and back then, after producing just a few thousand to 10,000 units, the die would snap right in half—copper would seep in at the center, eventually causing the die to split open, leaving it split in two. After he contacted me, I recommended this high-toughness LG die steel.
Cold extrusion dies for pure copper place the highest demands on the smelting quality and toughness of the die steel. If the die steel has poor smelting quality—such as segregation or microscopic cracks—metal particles will be forced into the die during the extrusion process, causing it to split open. At the same time, the die steel must possess high toughness; otherwise, the die will be crushed during the extrusion process. He previously used LD steel, and after 5,000 to 10,000 cycles, the die would snap in half. However, after switching to LG, the die’s service life has increased to 50,000 cycles. He even remarked that the dies are virtually indestructible and incredibly low-maintenance, adding: “LG is the nemesis of red copper.”
LG is a proprietary high-toughness die steel developed by Yuhui Die Steel. It is not a national grade and is not publicly available; it is our intellectual property and our company’s proprietary grade. LG mold steel has 8–9 times the toughness of DC53 and a hardness of 54–58 HRC. It’s so tough that you can bend it with a hammer without it breaking. The high hardness of 54–58 HRC provides sufficient strength for cold extrusion dies used with red copper; its toughness is so exceptional that it won’t break even if you bend it with a hammer—this is the fundamental guarantee that your dies won’t crack.
This netizen has used H13, counterfeit LG, and counterfeit 8566—all of which failed after 3,000–5,000 cycles. This is the result of using counterfeit mold steel. In contrast, my clients’ molds have gone from 5,000 to 10,000 cycles, and then directly increased to 50,000 cycles—a lifespan improvement of at least five times. Comparing 3,000–5,000 cycles to 50,000 cycles, the lifespan difference is more than tenfold—that’s a huge gap.
Using LG mold steel for cold-extrusion dies made of red copper is like stepping right into a liberated zone!
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Wu Dejian’s tool steel, the chief of staff of the user, bought everything he had used.