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Wire electrical discharge machining earns its place in a shop when nothing else will hold the tolerance: hardened tool steel, carbide, thin webs, sharp internal corners. But it is also one of the hardest processes to estimate, because it behaves nothing like conventional cutting. There is no tool pushing through the metal and no feed rate to read off a chart. A charged wire erodes the workpiece one spark at a time, and the removal rate is measured in square millimeters per minute, not millimeters of travel per minute. That single fact explains why wire EDM cost is built on cutting area, and why two parts with identical outlines can differ in price by a factor of three. This guide walks through the calculation step by step, from measuring cutting area off your drawing to a complete cost figure you can check any quote against.
On a mill or a lathe, cycle time follows the length of the toolpath. On a wire EDM, the wire must erode the entire cross-section it passes through, so cycle time follows the area of that cross-section. A 10 mm thick plate and a 60 mm thick block with the same profile are nowhere near the same job: the taller part presents six times the area along the identical path, and takes roughly six times as long to cut.
Three practical consequences follow:
Everything starts with two numbers you can measure directly off the drawing:
Cutting Area (mm²) = Total Cut Path Length (mm) × Part Thickness (mm)
Rough Cutting Time (min) = Cutting Area (mm²) ÷ Rough Cutting Rate (mm²/min)
The table below gives planning figures for a modern wire EDM on a single roughing pass. Treat them as starting points: generator settings, wire type, flushing conditions, and edge-quality requirements all move the real rate, and every shop calibrates against its own machine logs.
| Material | Typical Rough Cutting Rate | Relative Speed |
|---|---|---|
| Aluminum | 250–400 mm²/min | Fast |
| Copper / graphite | 200–350 mm²/min | Fast |
| Mild / tool steel | 180–320 mm²/min | Baseline |
| Hardened tool steel | 150–280 mm²/min | Slightly slower |
| Stainless steel | 150–260 mm²/min | Slower |
| Titanium | 100–180 mm²/min | Slow |
| Carbide | 80–150 mm²/min | Slowest |
The rough pass alone rarely meets the drawing. Tight tolerances and fine surface finishes require skim passes, which are lighter, faster cuts that re-trace the entire profile. Each skim removes very little material but still travels the full path, so a useful planning rule is to budget 40–60% of the rough-pass time for every skim pass.
| Quality Target | Typical Passes | Approx. Time vs. Rough-Only |
|---|---|---|
| Rough blank, around ±0.02 mm | 1 rough | 1.0× |
| General tolerance, good finish | 1 rough + 1 skim | ~1.5× |
| Tight tolerance, fine finish | 1 rough + 2 skims | ~1.8× |
| Precision die, mirror finish | 1 rough + 3 skims | ~2.2× |
This is why reading the tolerance and finish callouts is not optional. A die detail held to ±0.003 mm with a fine finish can take two to three times the machine time of a rough blank with the exact same outline.
Suppose you need a stainless steel insert, 25 mm thick, with a 300 mm outer profile and two internal windows of 80 mm each, toleranced at ±0.005 mm.
Total machine time comes to roughly two hours. At a burdened shop rate of $60–90 per hour, machine time alone lands around $120–180 for one part, before wire, material, and setup. And the extras are real: wire is consumed continuously and never reused, so a long unattended cut adds a genuine wire line item, and every internal contour needs a start hole drilled before the wire can thread. Three windows means three holes, three threading cycles, and three lead-ins.
A complete quote stacks four blocks on top of the cutting-area calculation:
Understanding the math helps you design smarter parts, and it helps you read a supplier's quote critically. When you send a drawing to ANOK, our engineers build the price exactly this way: cut path, thickness, material rate, pass count from your tolerance callouts, then wire, setup, and any secondary operations.
Our wire EDM department runs Sodick machines and holds tolerances as tight as 0.003 mm, with perpendicularity of 0.001–0.002 mm, minimum hole diameter of 0.07 mm, and surface finish down to Ra 0.8 µm. We cut hardened steel, titanium, carbide, graphite, and copper at up to 400 mm thickness and 500 mm diameter, all inside an ISO 9001:2015-certified, one-stop shop that also covers CNC machining, turning, surface grinding, and coating. If your part needs high precision wire EDM as one step in a larger machining package, we handle the full route under one roof.
Send your drawing to info@anok-machining.com or request a quote through our wire EDM machining services page, and you will get an itemized price built from your cutting area, not a guess.