How to choose wheel hub mold materials? H13、 Application scenarios of 8407 and ductile iron

How to choose wheel hub mold materials? H13、 Application scenarios of 8407 and ductile iron
H13 or 8407 for the mold cavity and ductile iron for the mold frame are common combinations, and material mismatch can result in a trade-off between lifespan and cost.
Two mainstream choices for cavity materials
H13 is the most commonly used hot work die steel in China, with a hardness of 45-52HRC, a relatively controllable price, and a short supply cycle.
8407 has higher purity, good isotropy, and better thermal cracking resistance than ordinary H13. The price is usually 30% -50% higher.
The difference in lifespan between the two on conventional wheel types is about 20% -30%. The advantages of 8407 are more obvious for high-end wheel types or thin-walled parts.
The difference between electric slag remelting and ordinary forgings
The content of inclusions in ordinary forgings is relatively high, and the transverse performance is lower than that in the longitudinal direction. The mold is prone to cracking along inclusions under repeated thermal cycles.
The sulfur and phosphorus content of electroslag remelted steel is lower, and its isotropy is improved. Under the same conditions, the lifespan can be increased by 20% -30%.
The price difference is about 25% -40%. Whether it is worth it depends on the target lifespan and replacement cost of the mold.
Mold frame materials are often underestimated
The mold frame is often made of ductile iron QT500-7 or medium carbon steel welded parts. Ductile iron has good shock absorption and is suitable for large tonnage machines.
The cost of welding formwork is low, but the rigidity uniformity is poor. After long-term use, the area near the weld seam is prone to deformation.
The price of the overall casting mold frame is 8% -12% higher, but it has good rigidity and is suitable for large-sized wheel hub molds.
Matching of inlay materials
Wheel rim inserts wear out quickly and can be treated with H13 nitriding. The impact of the spoke inserts is small, and ordinary H13 is sufficient.
There should be a difference in material hardness between the insert and the mold frame. The hardness of the two is similar, and they will bite into each other after long-term use, making disassembly difficult.
In the material scheme of the wheel hub mold, Xinfeng Mold will list the materials and heat treatment requirements by part, rather than uniformly labeling the entire mold.
Matching of materials and processes
The differential pressure mold can withstand higher differential pressure loads, and the template material needs to be selected from a higher strength grade. Ordinary low-pressure molds can be moderately relaxed.
The cavity of water-cooled molds needs to withstand greater temperature gradients, and the resistance to thermal cracking is more important than wear resistance.
The wear of gravity molds mainly comes from demolding, and the value of surface treatment is higher than that of upgrading the substrate material.
Balance between cost and lifespan
The material cost of a set of molds accounts for 30% -45% of the total price. The lifespan improvement brought about by material upgrades needs to be converted based on the number of modules.
The lifespan has increased from 30000 to 40000 cycles, resulting in a 25% increase in material costs and a 6% decrease in single cycle costs.
But if the product lifecycle is only 20000 cycles, material upgrades are a waste. The selection of materials should first depend on the actual output of the product.
Boundary of material substitution
Replacing 8407 with regular H13 can reduce the quotation by about 20%, but the risk of cracking in thin-walled wheel profiles increases. Substitution needs to have boundaries.
Before replacing, check the product output first. For projects with a lifecycle of only 10000 cycles, the impact of material degradation is controllable; It is not recommended to use more than 50000 molds.
Frequently Asked Questions
Question: What is the difference between H13 and 8407?
Answer: The price of 8407 is 30% -50% higher, and the lifespan is 20% -30% longer.
Q: What material is used for the mold frame?
Answer: QT500-7 ductile iron or medium carbon steel welded parts are commonly used.
Question: Is electric slag steel worth buying?
Answer: When the target lifespan is high, the price difference is 25% -40%.
Q: Should the hardness of the inlay be different from that of the mold frame?
Answer: Yes, the hardness is close and it will bite, making disassembly difficult.
Q: How much does material cost in the mold?
Answer: Usually 30% -45% is the main cost item.
Q: Do we need to upgrade materials for small product quantities?
Answer: No need, selecting materials based on actual production is more economical.
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