Mr. Liu contacted me to inquire about a high-strength, high-toughness steel. For small cores in injection molds for automotive connectors, we typically use various mold steels such as SKD61, SKD11, DC53, ASP23, VIKING, UNIMAX, and others. The part dimensions are 3 × 4 × 72; since the part is so small, it’s prone to breaking.
It’s just a small part—you’ve tried six different types of die steel, including high-toughness and high-hardness grades, but it still breaks.
It’s a small part measuring 3×4×72—it doesn’t use much mold steel, but the machining costs far exceed the material costs. If you don’t use the right mold steel, you’re definitely wasting money.
Many of the properties of mold steel are determined by the quality of the smelting process, not by the alloy composition. This is why so many people end up with mold steel of the correct grade but with the wrong properties.
For the small pins in connectors, I recommend high-toughness LG mold steel. Mr. Yu said that LG mold steel offers both hardness and toughness. The heat-treated hard grade with a Rockwell hardness of 60H is so tough that even the scrap left over from wire cutting won’t break when bent 180 degrees; it even springs back after the force is released. LG steel combines toughness with rigidity, and it’s been snapped up by a group of friends who make plastic molds. It works very well for wire-cutting slender pins.
Mr. Chen’s piercing pins used to break easily; whether he used 8407 or SKH51, they would snap. Both sets of molds would break alternately, and his mold operating conditions were similar to Mr. Liu’s. But now that he’s been using high-toughness LG mold steel for a month, there haven’t been any breaks. Mr. Chen praised Mr. Wu, saying, “Last time I bought a small piece of scrap material to make an insert; it’s been in use for a month, and it’s still working fine.”
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Wu Dejian’s tool steel, the chief of staff of the user, bought everything he had used.