A customer just came in to purchase 8503 mold steel for a non-stick application—nylon with 30% glass fiber—with a requirement of 1 million cycles.
The original molds used H13 and SKD61, but they started developing flash after producing just over 100,000 parts; this problem has been an ongoing issue for quite some time.
Mr. Zhong’s feedback once again demonstrates that H13 and SKD61—these medium-carbon hot-work die steels—are too hard and have too poor wear resistance to be relied upon for molds used with nylon reinforced with 30% glass fiber; they can only be used as a stopgap measure.
His feedback is consistent with reports from other users, who generally report that flash begins to appear at this production volume.
Both H13 and SKD61 are medium-carbon steels with a carbon content of 0.38% and a hardness of HRC 50. While they offer good toughness, their wear resistance is too poor to withstand the erosion caused by 30% glass-filled plastic, making the molds prone to flash.
For nylon + 30% GF, I still recommend the non-stick 8503 mold steel.
8503 is a proprietary non-stick mold steel developed by Wudejian Mold Steel. It has twice the toughness of DC53 and a hardness of 55–61 HRC. Compared to DC53, its performance is doubled without a corresponding increase in price, and it offers the added benefit of being non-stick.
In particular, this non-stick property, combined with its high hardness, is the fundamental and effective solution to the problem of molds used for high-glass-fiber-content materials—which are prone to being worn down, leading to flash on the product and surface roughness on the mold.
Mr. Yu from Ningbo said: “Using 8503 mold steel for glass-fiber-reinforced molds is really great—it can run continuously without any flash!” Boss Wan said that 8503 can withstand 1 million cycles with nylon + 30% glass fiber compound.
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Wu Dejian’s tool steel, the chief of staff of the user, bought everything he had used.