Comparison of Mold Steels: S136 / SKD61 / P20 / 8407
S136, SKD61, P20 and 8407 are four of the most widely used mold steels in the injection molding industry. Material selection must be based on a comprehensive evaluation of product requirements, production scale and cost budget. Below is a detailed comparison of these common mold steels to support engineering decisions.
Basic Composition and Grade Positioning
| Mold Steel | Standard / Chemical Composition | Type |
|---|---|---|
| P20 | 3Cr2Mo, Pre-hardened | Plastic Mold Steel |
| S136 | 4Cr13, Stainless Steel | Anti-corrosion Mold Steel |
| SKD61 | H13, 5CrNiMoV | Hot Work Die Steel |
| 8407 | Premium H13, High Purity | High Performance Die Steel |
Hardness and Heat Treatment Properties
| Mold Steel | Delivery Hardness | Heat Treatment | Quenched Hardness | Deformation |
|---|---|---|---|---|
| P20 | 28–32 HRC | No Need | 28–32 HRC | Small |
| S136 | 32–36 HRC | Quenched & Tempered | 48–52 HRC | Medium |
| SKD61 | 18–22 HRC | Quenched & Tempered | 48–52 HRC | Large |
| 8407 | 18–22 HRC | Quenched & Tempered | 50–54 HRC | Medium |
Key Performance Characteristics
| Mold Steel | Polishing | Corrosion Resistance | Toughness | Wear Resistance |
|---|---|---|---|---|
| P20 | Good | Poor | Good | Medium |
| S136 | Mirror | Excellent | Good | Good |
| SKD61 | Very Good | Medium | Excellent | Excellent |
| 8407 | Excellent | Medium | Superior | Superior |
Machinability and Production Cost
| Mold Steel | Typical Application | Estimated Service Life |
|---|---|---|
| P20 | Common Plastic Parts | 300,000–500,000 shots |
| S136 | Transparent & Medical Parts | 500,000–1,000,000 shots |
| SKD61 | High-volume & Engineering Plastics | 500,000–800,000 shots |
| 8407 | High-temperature & Long-life Molds | 800,000–1,200,000 shots |
Summary
In summary, P20 is a reliable, cost-effective choice for general applications. S136 is essential for corrosion resistance and high polish. SKD61 is a versatile performer for high-volume and high-temperature work. 8407 is the premium option for maximum durability in the most challenging conditions. The optimal choice depends on a careful balance of performance requirements, production volume and budget constraints.