Case Study: After a Six-Month Trial Period, the Customer Placed a Bulk Order for 23 Pieces of 8503 Mold Steel
This morning’s most significant order: Mr. Zhang, who injection molds PA66+GF30, placed a single order for 23 pieces of 8503 mold steel in four different specifications, moving from a trial period to bulk purchasing.
Mr. Zhang added me as a friend in September 2020 and contacted me on March 6 of this year, asking, “The mold inserts corrode after a short period of use. What mold steel do you recommend?”
After further discussion, it became clear that he was injection molding a generic brand of nylon reinforced with 30% glass fiber. He had originally used heat-treated S136 and DC53 hard mold steel for the mold inserts, but the molds would develop flash after producing only a small number of parts—flash appeared on the product’s outer diameter, and the mold surface showed obvious signs of being “eaten away.”
Analysis of the Failure Cause: Why couldn’t S136 and DC53 eliminate the flash?
Conclusion first: Injection molding PA66+GF30 (30% glass fiber content) causes severe mold erosion; the mold steel must simultaneously meet the requirements of “high wear resistance + non-stick properties.” S136 and DC53 each lack one of these properties, so both were incorrect material choices.
| Materials | Composition/Hardness | The Problem |
| S136 | 4Cr13 stainless steel, C ≈ 0.38%, approx. 50 HRC | It has good toughness but poor wear resistance; it cannot withstand glass fiber erosion, causing the mold core to be “eaten away,” resulting in flash on the product. |
| DC53 | High-carbon cold-work steel, C ≈ 1.0%, 60–62 HRC | It is wear-resistant but exhibits severe segregation, with a large number of microscopic cracks in the microstructure that are invisible to the naked eye; adhesive wear occurs between the glass fibers and these microcracks, which also leads to chipping. |
In a nutshell: S136 is tough but lacks wear resistance, while DC53 is wear-resistant but prone to microcracks—neither material is suitable for GF30 reinforced plastic applications.
Solution: 8503 Non-Stick Mold Steel
8503 is a proprietary non-stick mold steel developed by Wudejian Mold Steel. Key specifications:
| Item | Specifications |
| Hardness | 55–61 HRC |
| Toughness | Twice that of DC53 |
| Key Features | Non-stick + High hardness |
| Value for Money | Offers twice the performance of DC53 at the same price, plus the added benefit of non-stick properties |
Mechanism of Action: Non-stick properties combined with high hardness provide a fundamental and effective solution to the problems of “molds with high glass fiber content being eroded, product flash, and mold surface roughness.”
Industry Validation: Feedback from Boss Wan—Nylon + 30% glass fiber; 8503 withstood 1 million cycles without issues; Mr. Yu from Ningbo commented: “Using 8503 for glass-fiber-reinforced molds is really nice—it keeps molding without any flash!”
Customer Validation Process: From a single trial set to a bulk purchase of 23 pieces
1. March of this year: Mr. Zhang purchased one set of 8503 mold steel to test;
2. Over the following six months: He gradually ordered additional pieces, continuing to validate its performance during use;
3. Today, six months later: He placed a single order for four specifications, totaling 23 pieces, marking the transition to bulk purchasing.
The fact that the customer is willing to purchase in bulk demonstrates that 8503’s performance has successfully resolved his mold flash issues—this is a more powerful endorsement than any advertisement.
Conclusion
When injection molding high-glass-fiber-reinforced plastics such as PA66+GF30, the logic for selecting mold steel is: a base material with high wear resistance to prevent material sticking. S136 lacks sufficient wear resistance, while DC53 suffers from microcrack-induced adhesive wear—both will be “worn down” by the glass fibers. The 8503 mold steel, with its non-stick properties, high hardness of 55–61 HRC, and twice the toughness of DC53, is the fundamental solution to flash issues. This has been validated by a customer who has achieved 1 million mold cycles and placed repeat bulk orders.
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Wu Dejian’s tool steel, the chief of staff of the user, bought everything he had used.