Wire EDM is the process shops reach for when nothing else will hold the tolerance: hardened tool steel, tight internal corners, thin webs that would deflect under a milling cutter. It is also the process most often quoted badly, because it behaves nothing like the cutting people are used to. There is no tool pushing through the metal, no chips, no obvious feed rate to eyeball. A wire hangs in a dielectric bath and erodes the part one spark at a time, slowly, often overnight and unattended. Wire EDM cost is therefore almost entirely a question of time on the machine — and time on a wire EDM is driven by part height, cut length, and how many passes the tolerance demands, not by how the part looks at a glance.

This guide builds a wire EDM quote from the inputs you can actually measure off the drawing: cut area, cutting rate by material, the number of skim passes the callout forces, wire and threading cost, then setup and margin — from drawing to a number you can stand behind.

Why wire EDM is priced unlike any other cut

On a laser or a mill, the part footprint and the feed rate tell you most of the story. On a wire EDM, the dominant variable is the cross-sectional area the wire has to erode, because removal rate is measured in square millimetres per minute, not millimetres of travel per minute. A 10 mm thick part and a 60 mm thick part with the identical outline take wildly different times — the tall one has six times the area to erode along the same path.

Three things follow from that, and all three trip up estimators coming from conventional machining:

• Height matters as much as path length. Doubling the stack height roughly doubles the cut time, even though the program looks the same.
• Tolerance and finish multiply the time. Each skim (finishing) pass re-traces the whole profile. A part that needs ±0.005 mm and a mirror finish can take three or four passes; a rough blank-out takes one.
• The machine runs unattended, but it is not free. Lights-out running is the point of wire EDM, yet every hour the wire is cutting is a burdened machine hour you must recover.

The cost blocks of a wire EDM job

Break every quote into the same blocks so you can see which one is moving the price:

• Machine time — rough cut plus every skim pass plus threading, times the burdened EDM rate.
• Wire — brass or coated wire is consumed continuously and never reused; cost scales with cutting time and stack height.
• Material — the blank, plus the start holes drilled before the wire can thread.
• Setup and programming — fixturing, indicating the blank, generating the path, and the first start.
• Secondary cost and margin — fixed job cost amortised over the batch, plus the profit the job carries.

Add the first four for a cost; apply margin for a price.

Machine time: area, rate, and passes

Cutting time is the spine of the quote. Build it in five steps:

1. Cut path length — the total length of the profile the wire travels (outer profile plus every internal window, slot, and aperture), in millimetres.
2. Part height — the stack thickness the wire passes through, in millimetres. Cut area for the rough pass = path length × height.
3. Rough cut time = cut area ÷ the rough cutting rate (mm²/min) for that material and height.
4. Skim passes — add a pass for each finishing cut the tolerance and surface callout require. Skims remove little material and run faster, but each re-traces the full path; budget roughly 40–60% of the rough-pass time per skim as a planning figure, then calibrate against your machine.
5. Threading — count the separate start points (one per closed contour, e.g. each internal window) and add the automatic threading time per start.

Multiply the total time by the fully burdened EDM rate — depreciation on a machine that costs far more than a comparable mill, dielectric and filtration, power, floor space, and operator burden spread across mostly unattended hours. That rate is built per machine, not shop-wide; the machine shop hourly rate calculation guide shows how, and a wire EDM rate is usually well above your milling rate for exactly these reasons.

Typical rough cutting rates by material

A practical starting table for a modern wire EDM on a single rough pass. Treat these as approximate planning defaults to calibrate against your own machine logs — generator settings, wire type, flushing, and required edge quality all move them.

Material	Typical rough rate	Relative speed	Notes
Aluminium	250–400 mm²/min	Fast	Cuts quickest of the common metals
Mild / tool steel	180–320 mm²/min	Baseline	The reference most shops quote against
Hardened tool steel	150–280 mm²/min	Slightly slower	Hardness changes little vs. soft steel
Stainless steel	150–260 mm²/min	Slower	Lower conductivity, more flushing
Carbide	80–150 mm²/min	Slowest	Tough on wire; plan extra time
Copper / graphite	200–350 mm²/min	Fast	Conductive, erodes readily

A worked example: a 0.5 m (500 mm) profile cut through a 40 mm tool-steel stack is 500 × 40 = 20,000 mm² of area. At 250 mm²/min the rough pass is 80 minutes. Two skim passes at, say, 35 minutes each add 70 minutes. At a €90/hr burdened EDM rate, that is roughly (150 min ÷ 60) × €90 ≈ €225 of machine time before wire, material, setup, or margin — for one part.

Passes: where the tolerance callout sets the price

The single biggest driver estimators miss is the number of passes, and the drawing dictates it, not the geometry. A loose bracket detail blanked out in one pass and a die component held to ±0.003 mm with a Ra 0.2 finish can share the exact same outline yet differ two- or three-fold in machine time.

Quality target	Passes (typical)	Time vs. rough-only
Rough blank, ±0.02 mm	1 rough	1.0×
General tolerance, good finish	1 rough + 1 skim	~1.5×
Tight tolerance, fine finish	1 rough + 2 skim	~1.8×
Precision die / mirror finish	1 rough + 3 skim	~2.2×

This is why reading the tolerance and surface callouts off the drawing is not optional. Quote a precision die detail as a one-pass blank-out and you under-price it by half; quote a rough spacer with four passes and you lose the job. How tolerance and finish flow into cost is the whole subject of the G&T and tolerances for estimators guide, and on wire EDM it lands directly on the number of passes.

Wire, start holes, and the inputs people forget

Wire is consumed continuously — it feeds through the cut and is scrapped, never re-threaded. Cost scales with cutting time and with height, since taller stacks and faster generators burn wire faster. On a long lights-out job the spool cost is a real line item, not rounding error; coated wires for speed or carbide cost several times more than plain brass.

Before the wire can thread an internal feature, someone has to drill a start hole through the blank for every closed contour. Three internal windows means three start holes, three threads, and three lead-ins — drilling time and machine time that a glance at the outline never shows. Count the closed contours on the drawing and you have caught a cost most by-feel quotes miss.

Setup, batch, and applying margin

Setup and programming are fixed per job, not per part: squaring and indicating the blank, fixturing, generating and proving the path, and the first start take the same time for one part or fifty. Spread over one piece they dominate; spread over a batch they fade.

Batch size	Setup + programming (€150)	Contribution per part
1	€150	€150.00
5	€150	€30.00
20	€150	€7.50
50	€150	€3.00

Add machine time, wire, material, and amortised setup for a cost, then apply margin as arithmetic: price = cost ÷ (1 − margin %), the discipline explained in margin vs markup. The win is consistency — applying the same target every time so the easy aluminium jobs do not quietly subsidise the slow carbide ones. Where wire EDM is one operation inside a larger machined part, fold it into the full part cost the way how to price CNC machined parts lays out, and compare it against flat-cutting alternatives using the laser cutting cost calculation method when either process could do the job.

From drawing to wire EDM quote, the same way every time

The slow part of EDM quoting is the reading, not the arithmetic. Pulling material, stack height, total path length, the count of internal start holes, and — critically — the tolerance and finish that set the number of passes off a drawing by hand takes time, and under deadline pressure that reading gets shortcut: the height gets assumed, the skims get forgotten, the tight callout gets quoted as a rough blank.

QuoteBuddy reads the technical drawing and surfaces the inputs a wire EDM quote needs — material from the title block, geometry and contour count, internal features that require start holes, and the tolerance and finish callouts that drive the pass count — so the estimator works from a complete picture instead of a hurried scan. The cost engine then builds the price from your EDM rate, cutting rates, pass strategy, wire cost, setup time, and target margin the same way every time, so two estimators quoting the same part land on the same number.

Start a 30-day trial and run a few real EDM drawings through the process, from upload to an itemised quote PDF. See whether the cost it builds matches what you would have quoted by feel — and where the missed skim pass was quietly costing you margin.