Choosing the right mold material requires comprehensive consideration of five core factors: production volume, processing materials, product requirements, mold structure, and cost control. A systematic decision should be made based on the specific process scenario, rather than simply pursuing high-performance materials. The following is a detailed analysis and suggestions:
Material Selection Based on Production Volume
Large-scale production (over one million pieces): Prioritize high wear-resistant, long-life materials, such as high-carbon high-chromium steel (Cr12MoV) or cemented carbide (YG15), to ensure mold life matches production efficiency.
Small to medium batch or pilot production (thousands to tens of thousands of pieces): Lower-cost pre-hardened steel (such as P20), carbon tool steel (T10A), or aluminum alloys can be used to reduce initial investment.
Material Selection Based on Plastic/Processed Material Characteristics
Glass fiber reinforced plastics (such as PA+GF, PBT+GF): Severe wear requires high-hardness, high-wear-resistant materials, such as 718H and NAK80.
Corrosive plastics (e.g., PVC, POM): These release highly corrosive gases such as HCl and HF when heated. Corrosion-resistant steel (e.g., S136, 2083) must be used to prevent cavity corrosion failure.
Ordinary plastics (e.g., PP, PE): When surface finish requirements are not high, cost-effective pre-hardened steel (P20) is sufficient.
Material Selection Based on Product Precision and Surface Requirements
High-gloss, transparent, precision parts (e.g., optical lenses, medical accessories): Require excellent polishing performance and dimensional stability. Mirror-finish stainless steel (S136, NAK80) is recommended, achieving an ultra-smooth surface with Ra≤0.012μm.
Ordinary structural parts (e.g., housings, brackets): Surface finish requirements are low; economical materials such as P20 and 45 steel can be used.
