Douyin Store Inquiry: The temperature at the hot runner gate is 190°. When using H13 for small inserts, they tend to break. We’re now using beryllium copper; although they don’t break, they wear out easily and have a short service life—they break after only 3,000–5,000 cycles. The top of the small pin is only 1 mm, and the bottom is only 2 mm, and it’s secured on three sides.
For 1mm plastic mold core pins, H13 is currently used, but they break after 3,000–5,000 injection cycles. Switching to beryllium copper with lower hardness has improved the situation somewhat, but the service life remains short. To address this, the strength and toughness of the mold steel need to be improved. For these small core pins that are prone to breaking, I recommend the high-toughness LG mold steel, which has a proven track record of success in numerous applications.
LG is a proprietary high-toughness mold steel developed by Yuhui Company. LG’s toughness is 8 to 9 times that of DC53, with a hardness of 54–58 HRC. Its toughness is so exceptional that it will not break even when bent by hand.
Mr. Jin was injection molding nylon reinforced with 30% glass fiber. With a 0.5 × 0.5 specification, the low-hardness mold steel was prone to wear, causing the hole diameter to shrink and making subsequent assembly impossible. He switched to SKH51 high-speed steel, but it broke three times a month, and repairs were troublesome. Now, after switching to LG, there are no breakages, the hole diameter remains consistent, and the specification is not subject to wear.
Regarding the 1mm plastic mold with mating cores mentioned by this user, H13 is currently being used, but it breaks after 3,000–5,000 injection cycles. Even beryllium copper fails to resolve this issue, so high-toughness LG mold steel must be used instead.
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Wu Dejian’s tool steel, the chief of staff of the user, bought everything he had used.