Mold Steel Selection: P20, 718H, NAK80, S136 Comparison
Choosing the right mold steel is the foundation of high-quality plastic injection molds, directly affecting mold life, part precision, surface finish, and production efficiency. For overseas buyers, selecting suitable mold steel according to product requirements can not only reduce costs but also avoid delays caused by material mismatches. This article focuses on four commonly used injection mold steels—P20, 718H, NAK80, and S136—detailing their characteristics and applicable scenarios to help you make the best choice. At Yige Mold, we specialize in matching the most appropriate steel grades to your project needs, ensuring both cost-effectiveness and long-term performance.
P20 is the most widely used basic mold steel in the injection molding industry, and it is also the first choice for many cost-sensitive projects. It is a pre-hardened steel with a hardness of 28-32 HRC, which does not require heat treatment after machining, greatly shortening the mold manufacturing cycle. P20 has good machinability and toughness, but its corrosion resistance and wear resistance are general, and it is not suitable for products requiring high surface finish. It is ideal for mass production of ordinary plastic parts, such as daily necessities, packaging boxes, and low-precision electronic shells made of PP, PE, and other common materials. As a cost-effective option, P20 is especially suitable for overseas buyers with tight budgets and short delivery requirements. Yige Mold often recommends P20 for standard, high-volume projects where budget and speed are top priorities.
718H is an upgraded version of P20, with higher hardness (33-38 HRC) and better wear resistance and polishability. After quenching and tempering, it has more uniform tissue and higher dimensional stability, which can effectively reduce mold deformation during long-term production. Compared with P20, 718H is more suitable for molds with higher requirements on part precision and surface quality, such as automotive interior parts, high-grade plastic toys, and medium-precision electronic components. It can also be used for molds with complex structures and multiple cavities, and its service life is 1.5-2 times that of P20. For overseas buyers who pursue cost-performance and need to improve mold durability, 718H is a more balanced choice. Yige Mold leverages 718H for projects demanding tighter tolerances and extended mold longevity, ensuring consistent part quality over thousands of cycles.
NAK80 is a high-gloss pre-hardened steel, which is famous for its excellent polishability—after simple polishing, it can achieve a mirror surface effect (Ra≤0.02μm) without additional surface treatment. Its hardness is 37-43 HRC, with good toughness and dimensional stability, and no need for heat treatment after machining. NAK80 is mainly used for molds that require high surface finish of plastic parts, such as transparent parts (PMMA, PC materials), high-grade cosmetic packaging, and precision electronic product casings. It avoids the trouble of secondary processing such as electroplating, saves production costs, and is favored by overseas buyers in the high-end consumer goods industry. Yige Mold has extensive experience in NAK80 mold manufacturing, delivering premium mirror-surface parts for brands seeking a high-end finish.
S136 is a corrosion-resistant stainless steel, with excellent corrosion resistance, wear resistance, and high-temperature resistance, and its hardness can reach 48-52 HRC after heat treatment. It can resist the corrosion of corrosive plastics (such as PVC) and mold release agents, and maintain good surface quality even in long-term high-temperature production. S136 is suitable for molds of corrosive plastic parts, transparent parts with high requirements, and medical device parts (which require strict hygiene and corrosion resistance). Although its cost is higher than the other three steels, its long service life and stable performance can reduce the total cost of mold use for overseas buyers in the long run. Yige Mold specializes in S136 molds for medical, automotive, and corrosive material applications, ensuring compliance with strict industry standards and long-term reliability.
In summary, P20 is suitable for cost-sensitive ordinary parts, 718H for high-precision and durable molds, NAK80 for high-gloss surface parts, and S136 for corrosion-resistant and high-temperature-resistant projects. As a professional Chinese injection mold manufacturer, Yige Mold provides customized mold steel selection suggestions according to your product materials, precision requirements, and budget, ensuring mold quality with strict material inspection and processing technology. Contact us now for a free DFM analysis and mold quote!
Mold Steel Selection: P20, 718H, NAK80, S136 Comparison