Mr. Zheng asked，“What type of die steel is best for cell phone heat sinks? We’re cold-extruding 6063 aluminum heat sinks, and the teeth are prone to scoring. We’re currently using H13, but after producing about 20,000 units with a single die, scoring occurs.”
The cold extrusion dies for this type of aluminum heat sink feature narrow-edged, thin blanks, which place demands on both the die’s strength and toughness. Additionally, since aluminum dust is generated during the cold extrusion process, adhesive wear caused by sticking is likely to occur. Even slight wear or adhesion on the die can result in scoring.
H13 is a medium-carbon steel with a carbon content of 0.38%. After heat treatment, it has a hardness of 50 HRC and good toughness, but its wear resistance is somewhat lacking. Therefore, after a period of use, it wears down and causes sticking. The fact that it now develops scoring after producing 20,000 units further corroborates this. Therefore, this die requires a die steel with good toughness and high strength. Based on past experience, I recommend the high-toughness LG die steel.
LG is a proprietary high-toughness die steel developed by Yuhui Company. Its toughness is 8 to 9 times that of DC53, with a hardness of HRC 54–58; it is so tough that it will not break even if you bend it by hand. LG not only offers high toughness but also a high hardness of 54–58 HRC—a performance characteristic that H13 cannot match. Therefore, using high-toughness LG die steel for aluminum cold extrusion dies will result in a longer service life.
Our client, Mr. Luo, also manufactures cold-extruded pure aluminum heat sinks. The product structure is relatively complex, featuring narrow-edged, thin sheets. Originally, the dies were made of H13 steel, with a maximum service life of 15,000 cycles. However, after switching to LG die steel, the dies have produced over 40,000 units without cracking, tripling their service life.
Mr. Luo’s operating conditions and mold materials are similar to Mr. Zheng’s. Therefore, for Mr. Zheng’s cold extrusion molds for 6063 aluminum smartphone heat sinks—which currently use H13 and suffer from scoring after only 20,000 cycles—you can switch to high-toughness LG die steel to extend the service life and eliminate scoring.
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Wu Dejian’s tool steel, the chief of staff of the user, bought everything he had used.