How to Calculate the Wire Cutting Price
A practical walkthrough for engineers and buyers who need to check a wire EDM quote line by line. You will see how cut area, number of passes, machine hour rate and setup time combine, and which inputs you should never accept as a lump sum.
In this article
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Key takeaways
What actually goes into a wire cutting price
Wire EDM removes material with a traveling electrode, so the natural unit of work is the area swept by the wire, measured in square millimeters. A 10 mm thick plate with a 100 mm long cut removes 1,000 mm² of material. That number, not the part weight, is the first input in almost every quote you will see from a job shop.
The second input is how many times the wire travels that path. A single rough pass cuts fast and leaves a rough surface. Each additional trim pass is slower and narrower, so it adds time without removing much material. When you calculate the wire cutting price, the pass count is often the largest single variable between two shops quoting the same geometry.
The third input is the machine hour rate. This is not just electricity. It covers wire consumption, deionized water, filters, resin, the operator, and the depreciation on a machine that can cost more than a small house. A shop quoting a very low hourly rate is either running older equipment or has left something out of the rate.
- 1Cut areaProfile length × part thickness, summed over every cut.
- 2Pass countRough, semi-finish and trim passes each add time.
- 3Hour rateMachine, wire, consumables, labor and overhead.
- 4Fixed setupFixturing, threading, alignment and first-article check.
The four inputs you need before you can calculate the wire cutting price
Start with the drawing. You need the total length of every cut path, including start holes, slug removal cuts and any wire threads through the part. A part with three internal windows has three separate cut paths, and each one needs its own thread and approach move. Engineers often forget the approach and overtravel, which can add 5 to 15 percent to the cut length.
Next, record the thickness at each cut. A stepped part may be 40 mm at the outer profile and 12 mm at an internal slot. Multiply length by local thickness for each region, then add the areas together. Units must match: if length is in millimeters and thickness in millimeters, area is in square millimeters. A mixed-unit drawing is the most common source of a quote that is off by an order of magnitude.
Third, decide the surface finish and tolerance. Roughing alone might reach Ra 3.2 μm. A ±0.005 mm tolerance with Ra 0.8–1.6 μm typically needs one rough pass plus two or three trim passes. Each trim pass runs at a fraction of the roughing feed, so the time multiplier is larger than the material removed would suggest.
Fourth, note the material. Hardened tool steel, carbide and some superalloys cut more slowly and consume more wire. Aluminum cuts quickly but can be gummy and needs different flushing. The same geometry in 1045 steel and in TC4 titanium will not quote at the same number.
- 1Cut lengthInclude approach, overtravel and slug cuts.
- 2Local thicknessMeasure at each region, not just the maximum.
- 3Finish and toleranceThese set the number of trim passes.
- 4Material gradeAffects feed rate and wire consumption.
Turning cut area into cutting time
Every wire EDM machine has a recommended cutting rate for a given material, thickness and wire diameter. For a 0.25 mm brass wire in 50 mm thick 1045 steel, a rough pass might run at 20 to 35 mm² per minute. In hardened D2 at the same thickness, expect 12 to 20 mm² per minute. These are shop-floor starting points, not guarantees, because flushing and part geometry change the real number.
Divide the total cut area by the cutting rate to get roughing minutes. Then add trim passes. A typical trim pass removes a kerf of only a few hundredths of a millimeter, but it runs at 30 to 60 percent of the roughing feed. Two trim passes can add 40 to 80 percent of the roughing time, depending on the finish target.
Add non-cutting time: wire threading, re-threading after a break, tank fill and drain, and program prove-out. For a simple single-window part this might be 15 to 30 minutes. For a part with five internal profiles and tight positional tolerance, it can exceed two hours. This is why two shops can quote the same cut area very differently.
The output of this step is machine minutes per part. Multiply by the shop hour rate, divide by 60, and you have the variable cost per part. Setup is still separate.
- 1Roughing minutesTotal area ÷ cutting rate for that material and thickness.
- 2Trim minutes40–80 percent of roughing time for two trim passes.
- 3Non-cut timeThreading, tank cycles and prove-out.
How to read a wire cutting quote and spot bad numbers
A good quote separates cutting time, setup and material or wire consumption. If the supplier gives you one lump sum with no breakdown, ask for the cut area and pass count they assumed. A shop that cannot tell you the pass count is probably guessing, and the guess usually lands in their favor on tight-tolerance work.
Watch for the hourly rate trap. A low rate with a long estimated time can cost more than a higher rate with an efficient process. Ask what the rate includes: wire, filters, resin, water treatment, labor and inspection. If the answer is machine time only, the extras will appear elsewhere.
Check the tolerance-to-pass relationship. A quote that promises ±0.005 mm from a single rough pass is not credible on most materials. Conversely, a quote that charges four trim passes for a ±0.05 mm bracket is over-processing. The pass count should match the drawing callout, not the shop default.
Finally, ask about first-article inspection. For a prototype, the inspection time can be a meaningful share of the total. For a production run, it should be spread across the batch. A supplier who quotes inspection per piece on a 10,000-part order is padding the number.
- 1Ask for cut areaIt is the fastest way to verify the base number.
- 2Ask for pass countIt should follow the tolerance on the drawing.
- 3Ask what the rate coversWire and consumables are easy to hide.
- 4Ask how setup is amortizedFixed cost per job, not per piece, on repeat work.
Step by step: how to calculate the wire cutting price for one part
Work through these in order. Each step produces a number you can check against the supplier quote.
- 1Measure every cut pathTrace the drawing and sum the length of each profile, including start-hole approaches and overtravel. For a part with three windows, list three lengths. Add 5–15 percent for approach moves if the drawing does not show them.
- 2Multiply by local thicknessFor each path, multiply length by the thickness along that path. A stepped part may give 40 mm at the outer profile and 12 mm at an internal slot. Sum the areas. Keep everything in millimeters.
- 3Set the pass countOne rough pass for ±0.05 mm and Ra 3.2 μm. One rough plus two trims for ±0.01 mm. One rough plus three or four trims for ±0.005 mm and Ra 0.2–0.8 μm. Never assume a single pass will hold a tight tolerance.
- 4Pick a cutting rateUse 20–35 mm²/min for 1045 steel at 50 mm thick with 0.25 mm wire. Drop to 12–20 mm²/min for hardened tool steel or titanium. Aluminum can run faster, but flushing must be controlled to avoid wire breaks.
- 5Calculate cutting minutesDivide total area by the cutting rate. Add trim time at 40–80 percent of roughing time. Add 15–30 minutes of non-cut time for a simple part, more for multi-window work.
- 6Add setup and first-article timeAllow 1–3 hours for fixturing, alignment and prove-out on a new part. Repeat orders skip most of this. Amortize setup across the batch size, not across one piece.
- 7Apply the hour rate and check the resultMultiply machine minutes by the shop rate and divide by 60. Compare the total to a sanity check: simple plates usually fall in a narrow band per square millimeter, and any quote far outside that band deserves a question.
Typical inputs and their effect on wire cutting price
Use this as a quick check when a quote looks high or low.
| Input | Low-cost case | High-cost case | Effect on price |
|---|---|---|---|
| Tolerance | ±0.05 mm | ±0.005 mm | More trim passes, slower feed |
| Surface finish | Ra 3.2 μm | Ra 0.2–0.8 μm | Two to four extra passes |
| Material | Aluminum, mild steel | Hardened tool steel, TC4 | Lower cutting rate, more wire |
| Part thickness | 10–20 mm | 80–150 mm | Slower feed, harder flushing |
| Internal profiles | 1 window | 5 windows | More threading and non-cut time |
| Batch size | 10,000 parts | 1 prototype | Setup spread over fewer parts |
| Setup type | Repeat order | New complex fixture | 1–3 hours fixed per job |
The number is only as good as the inputs
Cut area and pass count decide most of the price. Get those two right before you argue about the hourly rate.
Wire cutting price questions engineers ask
Is wire cutting priced by weight or by cut area?
By cut area. The wire removes material along a path, so the cost tracks the swept area, which is path length times local thickness. Weight is a poor proxy because a thin, tall part and a thick, short part can weigh the same but require very different cutting times.
Some shops quote a minimum charge per part to cover handling. That is separate from the area-based cutting cost.
How much does each extra trim pass add to the price?
A trim pass removes very little material but runs at 30 to 60 percent of the roughing feed. In practice, two trim passes add 40 to 80 percent of the roughing time, depending on the finish target and material.
Going from a single rough pass to a four-pass finish can roughly double the cutting portion of the quote. The setup and handling stay the same.
Why do two shops quote the same part so differently?
Different assumptions about pass count, cutting rate and non-cut time. A shop with newer generators can run higher feed rates and may use fewer passes for the same finish. A shop running older equipment may add passes to compensate.
Ask each supplier for the cut area and pass count behind their number. The gap usually becomes obvious once those two figures are on the table.
Does the start hole count as cutting time?
Yes. Drilling or EDM-drilling a start hole is a separate operation, and it is charged either as machine time or as a fixed per-hole price. On a part with many internal profiles, start holes can add noticeable cost.
If the design allows, placing start holes in a slug that will be removed can reduce the number of threads and save time.
Can I reduce the wire cutting price without changing the design?
Sometimes. Increasing the batch size spreads setup over more parts. Relaxing a non-critical tolerance from ±0.005 mm to ±0.01 mm can remove one trim pass. Choosing a material that cuts faster, when the application allows, also lowers the rate.
These changes are best discussed before the drawing is frozen. Once the part is quoted and ordered, the options narrow.
How do I check a quote if I do not have a wire EDM machine?
Estimate the cut area from the drawing, pick a cutting rate from published tables for the material and thickness, and multiply by a reasonable hour rate. The result will not match exactly, but it tells you whether the quote is in the right range.
If the gap is more than about 30 percent, ask the supplier to explain the difference before you place the order.
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We quote from the cut area, the pass count and the material, so every line has a reason behind it.
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