CNC processing quotes UK: how a number is actually built

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  What a CNC processing quote is made of
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  Why the same part costs less at 200 pieces
• 3
  Where tolerance and finish change the price
• 4
  Lead time as a line item, not a promise
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  How to tell a complete quote from a thin one
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  What each specification change does to the quote

A CNC processing quotes UK figure is not a single price for a part. It is a stack of separate costs that a shop either absorbs or passes on. The stack has five layers: setup, machine time, material, finishing, and inspection. Each layer scales differently with quantity, which is why the same part can look expensive at one piece and cheap at 500.

Setup is a fixed cost. Fixture design, first-article proving, tool offsets and program verification are paid once per batch. On a simple plate that might be 30 minutes. On a five-axis part with three datums and a thin wall, it can run past two hours. Split the setup across 1 part and it dominates the quote. Split it across 200 and it nearly disappears.

Machine time is variable. It follows the volume of material removed, the number of tools, and the spindle hours the part occupies. A part cut in 18 minutes on a three-axis mill is not priced like a part that needs 90 minutes on a simultaneous five-axis center with a Ø400 mm rotary table. The hourly rate differs, and the hours differ more.

Material and inspection sit at the two ends. Bar stock or plate is priced by weight plus a cut charge, and titanium or Inconel moves that line far more than aluminium does. Inspection is the quiet cost: 100% inspection before shipment means every part is measured, and a CMM program for a tight feature adds hours that a purely visual check never would.

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  FixedSetup, fixturing, first-article proving
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  VariableMachine time, tool wear, spindle hours
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  ScaledMaterial by weight, finishing by surface area
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  Add-onCMM programming and inspection time

Quantity changes the quote because it changes which layer dominates. At one piece, setup and programming are spread over a single unit, so they can be 60 to 80 percent of the line. At 200 pieces, the same fixed block is divided by 200 and the quote becomes almost pure machine time plus material.

This is the reason a prototype quote and a production quote for identical geometry can differ by a factor of five. It is not a discount. It is arithmetic. If a supplier drops the price at volume without changing anything else, they were carrying margin at the low quantity, not losing money at the high one.

There is a floor, though. Some costs do not divide. Material is per part. Finishing is per part. Inspection is per part. Once setup is negligible, the only way to move the number is to change the part: looser tolerance, fewer setups, or a finish that can be applied in a tumbler rather than by hand.

Tooling life also behaves differently at volume. A batch of 20 may run on one set of inserts. A batch of 2,000 in hardened 4140 will consume several, and a shop that has run the job before will price that in. A shop quoting blind may not, which is how a cheap quote turns into a renegotiation at week three.

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  1–5 partsSetup and programming dominate the line
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  50–200 partsMachine time and material dominate
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  1,000+ partsTool life and fixturing amortisation matter

Tolerance is the single most quoted number and the least understood cost lever. Moving a general tolerance from ±0.1 mm to ±0.005 mm does not just require a better machine. It requires a different process plan: roughing with stress relief, semi-finishing, then finishing passes with temperature-stable coolant, plus more frequent in-process checks.

Surface finish works the same way. As-machined at Ra 1.6–3.2 μm comes off a normal finishing pass. Ra 0.8–1.6 μm needs a finer stepover or a dedicated finish tool. Ra 0.2–0.8 μm usually means a separate operation, sometimes on a different machine. Each step adds time per part, and time per part is the line that repeats.

Geometry is the third lever and the hardest to see on a drawing. A deep pocket with a 3:1 depth-to-diameter ratio is routine. At 8:1, tool deflection and chip evacuation change the cutting strategy, feed rates drop, and the quote reflects it. Thin walls behave similarly: the part moves, so passes get lighter.

Materials set the baseline rate. Aluminium 6061 and 6082 cut fast and forgive. Stainless 316 and 17-4PH work-harden and need lower feeds. Titanium TC4 and Inconel generate heat at the cutting edge and shorten tool life sharply. The geometry may be identical between two quotes; the material line is what makes one double the other.

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  ±0.1 mmStandard milling, no special process plan
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  ±0.005 mmStaged passes, thermal control, more checks
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  Ra 0.8–1.6 μmFiner stepover or finish tool
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  Ra 0.2–0.8 μmSeparate finishing operation

Lead time enters a quote in two ways: as a schedule the shop can hit, and as an expedite premium it may or may not offer. A quotation and free DFM analysis within 12 hours is about the quoting stage. Production can start within 24 hours once the drawing and material are settled. Parts ship in 3–5 days for straightforward work.

Those windows assume the input is complete. A STEP file with no tolerances, no material callout and no finish note forces a shop to guess, and guesses come back as revision requests. Every revision cycle adds a day or more before the spindle ever turns. The cheapest way to shorten a quote is to send a fully specified package the first time.

Expediting has a real cost because it reshuffles the shop. A machine freed for your job is a machine taken off someone else's. Shops that price this honestly will show it as a separate line or decline it. Shops that absorb it quietly are usually pushing the delay onto another customer.

Historical late-delivery probability below 2% is what a stable schedule looks like. It is not a guarantee, and no honest shop offers one. What you can ask for is the planned start date, the machine assigned, and the inspection stage that gates shipment.

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  Quote stage12 hours including free DFM analysis
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  StartProduction can start within 24 hours
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  ShippingParts ship in 3–5 days
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  RiskHistorical late-delivery probability below 2%

A quote you can act on names the material grade, the tolerance class, the finish, the inspection level and the delivery window. A quote that says only "CNC machining, per drawing" is a placeholder. It will change once the shop reads the drawing properly, and the change is rarely downward.

Ask which machine is planned. The answer tells you whether the shop understood the part. A 4,000 mm gantry job will not run on a 500 × 500 × 450 mm compact mill, and a part needing five faces in one setup will not come off a three-axis machine without extra fixtures. If the machine is named and it fits, the quote is grounded.

Ask what is excluded. Deburring, heat treatment, plating, laser marking and packaging are commonly separate. Laser marking has a minimum character height of 1.5 mm, which matters for part numbers on small features. If these are not listed, they are either included or they will be added later.

Finally, check the confidentiality terms. Uploads should be secure and confidential, and an NDA is available on request. If a shop cannot describe its data handling in one sentence, that is a signal about everything else in the quote.

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  NamedMaterial grade, tolerance, finish, inspection
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  MachineWhich machine and how many setups
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  ExclusionsDeburr, heat treat, plating, marking
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  ConfidentialitySecure uploads and NDA on request