CNC Processing Price Guide: What Actually Drives Your Quote

• 1
  Key takeaways
• 2
  Cost driver vs. what it changes and how to control it
• 3
  Quantity and setup: the part of the price you can actually move
• 4
  Tolerance and geometry: where the price steps up
• 5
  Material and surface finish: two lines that surprise buyers
• 6
  Quality, documentation and lead time
• 7
  How to compare two CNC machining quotes fairly
• 8
  Step by step: how to get a quote you can trust

Every CNC job starts with fixed work: CAM programming, fixture design, first-article measurement. That block of hours is the same whether you order one part or one thousand. On a 20-part order, setup may be 40 percent of the invoice. On a 2,000-part order it drops under 5 percent. This is why the same drawing gets two very different unit prices.

Cycle time is the variable part. It scales with material removal volume, the number of tools, and how many setups the part needs. A block that fits in one vise and machines from three sides runs in minutes. The same envelope with an undercut and a 0.4 mm wall needs a second op, a soft jaw, and a slower feed to avoid chatter.

Tool life is the quiet line item. Cutting 17-4PH or Inconel wears carbide fast, so the shop budgets more inserts per part. Aluminum 6061 barely touches tool wear. If your design allows 6061-T6 or 6082 instead of a stainless grade, the cycle time and tooling cost both fall.

The practical move: send the full annual volume with your prototype order. Shops price the batch, not the piece. At GreatLight we run from one prototype to 10,000+ part runs with no minimum order quantity, so you can start small and let the price curve follow the volume.

• 1
  Fixed costProgramming, fixture, first article. Paid once per revision.
• 2
  Variable costCycle time, tool wear, operator attention per part.
• 3
  Watch forA quote that ignores setup usually reappears as a tooling charge.

Tolerance is not linear. Going from ±0.1 mm to ±0.05 mm is routine on a good 3-axis mill. Going to ±0.01 mm starts to need temperature control, sharp tooling and a warm-up cycle. At ±0.005 mm (about ±0.0002 in) you are often grinding or using a jig, and the shop has to hold the part, not just cut it.

The trap is applying a tight tolerance to the whole drawing instead of the features that matter. A bearing bore, a dowel hole and a sealing face need it. A clearance slot does not. GD&T helps here: a position tolerance of Ø0.05 mm MMC is cheaper to inspect and often cheaper to machine than a stack of plus/minus dimensions.

Geometry drives setup count. A part that can be reached from three orthogonal faces runs on a 3-axis machine. Add a compound angle or an undercut and you move to 4-axis or 5-axis. GreatLight runs 16 simultaneous 5-axis machining centers, 12 four-axis mills, and 27 three-axis machines, so the quote reflects the cheapest machine that can hold the tolerance, not the most expensive one in the shop.

Thin walls are their own cost category. Below roughly 1 mm in aluminum or 0.8 mm in stainless, chatter and deflection start to dominate. You pay for lighter cuts, more passes, and sometimes a support fixture. Design ribs or increase wall thickness where the part allows it.

Our 5-axis centers reach 4,000 mm maximum processing size, with rotary table capacity to Ø400 mm. Large parts are not automatically expensive; awkward parts are.

• 1
  Routine±0.05 mm on a 3-axis mill, standard tooling.
• 2
  Controlled±0.01 mm with warm-up, sharp tools, in-process checks.
• 3
  Special±0.005 mm often means grinding or a dedicated fixture.

Material cost per kilogram is only part of it. Machinability decides cycle time. Free-cutting brass C36000 and aluminum 6061 cut fast and leave a good finish. Stainless 316L work-hardens and needs slower feeds. Titanium TC4 (Ti-6Al-4V) and Inconel hold heat at the cutting edge, so tool life drops and the shop plans for more inserts and lower speeds. A material swap can change a quote by more than any finish choice.

Stock form matters too. Plate, bar and near-net forging have different lead times and different waste. A part machined from 20 mm plate may need a 40 mm billet if the geometry demands it, and you pay for the chips. Ask what stock size the quote assumes.

Surface finish is specified as Ra. As-machined aluminum typically lands around Ra 1.6–3.2 μm. A good fine cut reaches Ra 0.8–1.6 μm. Below that, into Ra 0.2–0.8 μm, you are usually polishing, lapping or bead blasting, which is manual work and priced per part, not per hour of spindle time.

Coating is a separate line again. Clear anodizing is cheap and common. Hardcoat anodizing builds a thicker oxide layer and changes dimensions slightly, so masking and re-measurement come into the price. Electroless nickel, zinc plating and powder coating each carry their own minimum batch charge.

• 1
  Cheapest to cut6061-T6, 6082, C36000 brass, POM
• 2
  Middle1045, 4140, 303/304 stainless, 17-4PH
• 3
  SlowestTC4 titanium, Inconel, magnesium AZ91D

Inspection is priced by what you ask the shop to prove. A dimensional check with calipers and micrometers is included in most quotes. A full CMM report, a first article inspection report, or material certification with heat lot traceability adds engineering time. In regulated work, that time is not optional, but it should be quoted as a visible line rather than buried.

GreatLight inspects 100 percent of parts before shipment, covering raw material check, in-process monitoring and final inspection, with reports on request. That structure keeps the routine work fast and puts the documentation cost where it belongs. If your industry needs ISO 9001:2015, IATF 16949:2016, ISO 13485:2016 or ISO 27001:2022 paperwork, say so at the RFQ stage, not after the parts are made.

Lead time has a price because it consumes capacity. A shop that can start production within 24 hours and ship parts in 3–5 days is holding open machine time, and expedited jobs push other work aside. The honest way to read a fast quote is to ask what the standard lead time is and what the expedite premium buys.

Volume changes the logistics, not just the machining. One prototype ships in an envelope. A 10,000-part run needs trays, separators, labeling and a packing plan that protects the finish. That packaging is a real cost line and it should appear in the quote.

• 1
  IncludedIn-process checks, final dimensional inspection, standard packing
• 2
  Quoted separatelyCMM reports, FAIR, material certs, custom packaging
• 3
  Ask upfrontWhich certifications your buyer needs on file

Two quotes on the same drawing often differ by 30 percent or more, and the gap is rarely the machine rate. It is usually the assumptions. One shop quotes a single setup on a 3-axis mill and assumes a loose tolerance on the non-critical faces. The other quotes 5-axis and holds everything tight. Both are correct answers to different questions.

Start by comparing the scope, not the number. Does the quote include material certification? Deburring? Anodizing? Shipping? A quote without finishing may look 15 percent cheaper until the finishing invoice arrives. Ask for a line-item breakdown: material, machining, finishing, inspection, packaging.

Then check the tolerance callout. If the quote says ±0.05 mm and your drawing says ±0.01 mm on three features, you are comparing different parts. Send the drawing with GD&T and let the shop respond feature by feature. A good shop will come back with DFM notes: relax this radius, add a clearance here, and the price drops.

Finally, look at the revision policy. Design changes are normal. Ask how a revision is priced, whether the fixture can be reused, and how fast a re-quote comes back. A partner who answers those questions in writing is cheaper over a program than one who answers them after the PO.

GreatLight has run this process since 2011 across three wholly-owned plants and 7,600 m² of floor space, with 150 technicians and 127 high-precision CNC machines. That capacity is what makes a 12-hour quote with free DFM analysis realistic rather than a sales promise.

• 1
  Compare scope firstMaterial, machining, finishing, inspection, packaging
• 2
  Then compare assumptionsSetup count, tolerance per feature, stock size
• 3
  Then compare change costRevision pricing and re-quote turnaround