PA66 is one of the most commonly used engineering plastics, featuring high strength, toughness, heat resistance, and wear resistance. It is widely applied in automotive parts, connectors, housings, gears, and structural components. However, PA66 has a high melting temperature, strong mold corrosion, and significant abrasiveness, especially when glass fiber reinforced. Therefore, mold material selection must consider hardness, wear resistance, corrosion resistance, thermal stability, and polishability. Improper material selection leads to rapid mold wear, rust, dimensional deviation, and high maintenance costs.
Basic Requirements for PA66 Mold MaterialsPA66 melts at 250–270°C and releases acidic gases during processing, causing corrosion. Glass fiber-reinforced PA66 strongly abrades the cavity, runners, and gates. Mold materials must therefore provide excellent wear resistance, corrosion resistance, thermal stability, and machinability. Materials must also maintain stable hardness during long-term production and resist deformation under cyclic heating and cooling.
Material Selection for Non-Reinforced PA66For non-reinforced PA66 with low to medium production volume, pre-hardened mold steels are suitable due to their low cost and ease of machining. 718H is widely used for internal structural parts, with hardness HRC 33–37. NAK80 is preferred for appearance parts, offering high polishability and hardness HRC 38–42, enabling mirror finishing without heat treatment.
Material Selection for Glass Fiber Reinforced PA66GF-reinforced PA66 requires high-wear materials. H13 (SKD61) is the most common choice, with heat-treated hardness HRC 48–52, offering excellent wear and heat resistance. S136 and S136H are stainless steels with superior corrosion resistance and polishability, suitable for high-quality appearance parts and humid environments.
Materials for High-Performance and Long-Life MoldsFor high glass fiber content, high precision, and ultra-high production volume, premium materials are required. STAVAX provides superior corrosion resistance and purity. VIKING offers ultra-high wear resistance and toughness. ASP23 powder metallurgy steel is used for gates, runners, and inserts to achieve extremely long service life.
Material Selection by Mold ComponentCavity and core: 718H, NAK80 for non-GF; H13, S136 for GF; STAVAX, VIKING for high GF.
Gates, runners, and inserts: H13, SKD61, ASP23.
Slides and lifters: H13, SKD61 for balanced wear resistance and toughness.
Mold bases: S50C carbon structural steel.
ConclusionPA66 mold material selection depends on glass fiber content, production volume, appearance requirements, and environmental conditions. Reasonable grading and component-based material matching ensure long mold life, stable production, and cost efficiency.
