D-top Mould Steel select guide

Mold Life Grades and Material Selection

1. Mold Life Grades
   Molds are divided into five grades by mold life:

• Grade 1: Over 1 million cycles

• Grade 2: 500,000 to 1 million cycles

• Grade 3: 300,000 to 500,000 cycles

• Grade 4: 100,000 to 300,000 cycles

• Grade 5: Below 100,000 cycles

Grade 1 and 2 molds require hardness around HRC 50 to avoid wear and ensure product accuracy.

2. Material Requirements
   High-grade molds need steels with good heat treatment and machinability. Grade 3 molds often use pre-hardened steels like S136H, 2316H, and 718H (HB270-340). Lower grades may use 45# steel (S50C) or machine cavities directly on the mold base.

3. Common Mold Steels
   Typical steels include:

• Sweden: 8407, S136

• USA: 420, H13

• Europe: 2316, 2344

• Japan: SKD61, BC53

4. Based on Plastic Corrosion

• Strongly corrosive plastics: S136, 2316, 420

• Weakly corrosive plastics: SKD61, NAK80, PAK90, 718

5. Appearance Considerations
   For transparent or mirror-finish parts, S136 is preferred, followed by 420. Other suitable steels include 2316, 718H, NAK80, and PAK90.

In short, choosing the right steel depends on mold life, corrosion resistance, and product appearance. Proper selection improves mold durability and product quality.