Electrical Discharge Machining (EDM) parameters must be adjusted based on the steel grade being machined. Using incorrect settings causes excessive electrode wear or poor surface finish.

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?