EDM MRR Calculator

Formula

• MRR = (k × E × f) / H_m
• E in joules (mJ × 0.001), f in Hz, H_m in J/mm³
• P_total = E × f, P_useful = k × P_total

About this calculator

Part of our Machining & CNC Calculators collection. Cutting speed, feeds, RPM, cycle time, and tap drill charts.

How it works

Material removal rate equals process efficiency times discharge energy times pulse frequency, divided by material melting energy per volume. Total and useful power show electrical demand at the spark gap. Tune Hm for your workpiece material.

Enter your values in the inputs above and click CALCULATE. Results appear on the right without a page reload. No login and no server upload.

Worked example

0.5 mJ discharge, 5000 Hz, 35% efficiency, steel Hm = 56.4 J/mm³.

1. E = 0.0005 J
2. MRR = 0.35 × 0.0005 × 5000 / 56.4 = 0.0155 mm³/s
3. MRR = 0.932 mm³/min
4. Total power = 0.0005 × 5000 = 2.5 W

Result: 0.932 mm³/min MRR, 2.5 W total gap power, 0.88 W useful.

When to use

• Estimating EDM productivity from pulse parameters
• Comparing roughing vs finishing pulse settings
• Relating electrical power to material removal

Limitations

• Hm varies with electrode/workpiece material and flushing
• Efficiency k is empirical (typically 0.2–0.4)
• Does not model electrode wear or surface finish

FAQ

What is melting energy Hm?

Energy required to melt and remove a unit volume of workpiece material. Steel is often about 56 J/mm³; carbide is higher.

Why is MRR so low compared to milling?

EDM removes material by discrete sparks, not continuous cutting. MRR of 1 mm³/min is typical for finishing; roughing can be higher.

Does discharge energy include voltage and current?

Enter the measured or calculated energy per pulse in mJ. E ≈ V × I × pulse on-time for a simplified estimate.