General guidelines by material:

P20 (1.2311) - Pre-hardened mold steel

• Roughing current: 6-12A
• Finishing current: 1-3A
• On-time: 100-300 microseconds
• Typical MRR: 25-40 mm3/min
• Notes: Easy to EDM, moderate electrode wear

H13 (1.2344) - Hot work tool steel

• Roughing current: 8-15A
• Finishing current: 2-4A
• On-time: 80-200 microseconds
• Typical MRR: 20-30 mm3/min
• Notes: Higher wear on electrode, use copper-tungsten for finishing

S7 - Shock-resistant tool steel

• Roughing current: 6-10A
• Finishing current: 1-2A
• On-time: 50-150 microseconds
• Typical MRR: 15-25 mm3/min
• Notes: Carbide precipitation risk if on-time too long

Stainless grades (420SS, 416SS)

• Roughing current: 4-8A
• Finishing current: 1-2A
• On-time: 50-100 microseconds
• Notes: Use positive polarity, expect 30 percent slower MRR

Electrode materials recommendation:

• Graphite: Best for roughing P20 and H13
• Copper: Better surface finish, preferred for fine details
• Copper-tungsten: For difficult materials and thin ribs
• Tellurium copper: Deep slots and fragile features

Always run a test block before cutting production cavities. What EDM settings work best in your shop?

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