How to Quote CNC Machine Jobs
This guide is for design engineers, sourcing engineers and shop estimators who need to price a machined part and compare supplier quotes on the same basis. Work through the seven steps in order. You will finish with a cost breakdown you can defend in a supplier review, plus a clear list of the inputs that move price the most.
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Key takeaways
Read the drawing before you quote anything
The quote starts with the drawing, not with a price list. Open the 2D PDF and the 3D STEP file side by side. Check that revision numbers match. A quote built on rev A when the customer is on rev C is wasted work, and it happens more often than shops admit.
Pull out five numbers first: overall envelope, tightest tolerance, tightest surface finish, material grade and quantity. If the drawing says 6061 without a temper, ask for the temper. 6061-T6 and 6061-O machine at very different feeds, and the price gap is real. The same applies to 17-4PH in condition A versus H900.
Mark every feature that needs a second operation. Cross holes, deep pockets, undercuts, internal threads below M3 and any surface that cannot be reached from one direction. A part that looks simple in 3D can need four setups once you plan the tool approach. Write those features down before you open a cost sheet.
Finally, check the units. Mixed metric and imperial callouts on the same drawing cause scrapped parts. Confirm the primary unit system in writing with the customer and note it on the quote.
- 1Revision checkConfirm 2D and 3D files are the same revision and match the PO.
- 2Material temperAsk for temper or condition, not just the alloy name.
- 3Hard-to-reach featuresList every feature that needs a second or third setup.
- 4UnitsState metric or imperial in writing on the quote.
How to set tolerance and finish targets in the quote
Tolerance is the biggest single cost lever on most parts. General tolerances of ±0.1 mm let a shop run a stable process with standard tooling. Tightening a feature to ±0.005 mm forces light finishing passes, temperature control and often a second inspection pass. Only the mating surfaces need the tight call. Everything else can stay loose.
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 controlled finish pass with sharp tooling. Anything below Ra 0.8 μm usually means extra operations, and on some materials it points to lapping or polishing rather than turning.
GD&T callouts add inspection time. A true position callout of Ø0.05 mm MMC can be checked with a functional gauge on the shop floor. The same callout without MMC often needs a CMM, which adds programming and queue time to the quote. Ask which dimensions the customer will actually measure at incoming inspection.
A practical rule: quote the drawing as written, then offer a second line at looser tolerance if the function allows it. That gives the customer a real choice instead of a single number they cannot argue with.
- 1Tight only where it mattersApply ±0.005 mm to mating features, not the whole part.
- 2Finish bandsRa 3.2 as-machined, Ra 0.8–1.6 controlled, below Ra 0.8 needs extra work.
- 3MMC gaugesBonus tolerance callouts can cut CMM time out of the quote.
Estimate cycle time from material removal, not from part size
Cycle time is the core of any CNC quote. Start with the stock envelope and the finished part. Subtract finished volume from stock volume to get the material you have to remove. Then pick a removal rate for the material and the machine. Aluminium on a 5-axis center removes fast. Inconel and titanium remove slowly, and the tool wears faster.
Roughing, semi-finishing and finishing are separate lines in your estimate. Roughing at high feed with a large cutter, semi-finishing to leave 0.2–0.3 mm, then finishing at light depth of cut. If you quote one blended number you will be wrong on both hard and soft materials.
Add non-cutting time. Tool changes, rapid moves, probing and part load all count. On a small part with many tools, non-cutting time can reach 30 percent of the total. That is why a 30 mm bracket with 12 tools can take longer than a 300 mm plate with 4 tools.
Finish with a reality check. If your estimate says 8 minutes and the part needs 6 setups and 40 holes, the estimate is wrong. Rebuild it from the feature list you wrote in step 1.
- 1Removal rate firstPick a rate per material and machine class, not a guess.
- 2Three passesRough, semi-finish, finish as separate lines.
- 3Count non-cutting timeTool changes and probing can be 30 percent of cycle.
Quantity, tooling and lead time in the quote
Quantity changes the cost structure, not just the total. For one to ten parts, programming and fixturing dominate. For 100 to 1,000 parts, cycle time dominates. Above 1,000 parts, it is worth quoting a dedicated fixture and a second operation machine to cut load time. Quote each volume band separately so the customer sees where the price breaks.
Tooling is the line most often left out. Standard end mills and drills are consumables and belong in the hourly rate. Form tools, custom broaches, special taps and dedicated fixtures belong on their own line. If the customer owns the fixture, say so in the quote. If the shop keeps it, say that too.
Lead time has three parts: programming and DFM, material procurement, and machining plus finish. Material is the wild card. A common aluminium grade ships in days; a special titanium or Inconel grade can take weeks. Note the assumption in the quote rather than promising a date you cannot control.
Do not quote a delivery date you cannot hold. State the lead time as a range with the material assumption attached. That protects both sides when the mill shipment slips.
- 1Quote volume bandsPrice 1, 10, 100 and 1,000 parts as separate lines.
- 2Separate toolingList custom fixtures and form tools apart from consumables.
- 3Material lead timeNote the grade and the assumed mill lead time on the quote.
How to compare supplier quotes line by line
Two CNC quotes for the same part often differ by more than the part cost, because they include different work. Put both quotes into the same five lines: material, machining, finish, inspection and freight. If a line is missing, the price is not comparable yet. Ask the supplier to fill it in.
Check the assumptions under each line. A low machining number with no inspection line usually means the part ships on a first-article check only. A low material number may mean the supplier quoted a smaller stock size and plans to skim it, which can move a feature out of tolerance.
Look at the tolerance and finish the supplier assumed. If one quote assumed ±0.05 mm and another assumed ±0.005 mm, they are not quoting the same job. Send the drawing revision again and ask both to confirm the tightest tolerance and finish they priced.
The lowest number is not automatically the best. A quote that lists its assumptions lets you compare, negotiate and plan. A quote that is one number with no breakdown gives you nothing to work with when the part changes.
- 1Same five linesMaterial, machining, finish, inspection, freight.
- 2Assumption checkTolerance, finish and stock size must match across quotes.
- 3Change controlAsk how a revision change is repriced before you place the order.
Step by step: how to quote CNC machine jobs
Run these seven steps in order. Each one feeds the next.
- 1Build the part file setCollect 2D PDF, 3D STEP and the material certificate requirement. Confirm revision and units in writing. Missing files are the most common cause of a quote that has to be redone.
- 2List features and setupsWrite every machined feature and assign it to a setup direction. Use 3-axis for open faces, 4-axis for wrap-around work, 5-axis when two angled faces must share one datum. Count setups; each one adds fixture cost and tolerance stack.
- 3Choose stock and material gradePick the closest standard stock size and add 2–3 mm per side for clean-up. Confirm temper or condition. Oversized stock raises material cost and cycle time, so do not default to the next big plate.
- 4Set tolerance and finish per featureApply ±0.005 mm only to mating features. Use Ra 1.6–3.2 μm as-machined for non-critical faces. Note which dimensions need CMM inspection and add that time to the quote.
- 5Estimate cycle time per operationUse removal volume and a removal rate for the material. Split roughing, semi-finishing and finishing. Add tool change, probing and load time. Allow 10–20 percent for tool wear on hard materials.
- 6Add finish, inspection and freightPrice anodizing, plating, powder coating or bead blasting as separate lines. Include 100 percent inspection before shipment and any report the customer asks for. Freight is a quote line, not an afterthought.
- 7Add margin and review the totalApply the shop margin, then test the number against similar parts you have run. If the total looks too low, check whether you missed a setup or an inspection step. Send the quote with assumptions listed so the customer can challenge them.
Which machining route fits the part
Use this table before you lock a price. The route changes both the setup count and the tolerance you can hold.
| Part condition | Route | Typical tolerance | When it does not fit |
|---|---|---|---|
| Open faces, one direction of access | 3-axis milling | ±0.02 mm | Undercuts or cross holes |
| Features on four sides | 4-axis with rotary table | ±0.01 mm | Angled faces off the rotation axis |
| Angled faces sharing one datum | 5-axis simultaneous | ±0.005 mm | Simple flat plates, cost not justified |
| Shaft-type parts under Ø65 mm | Swiss or mill-turn | ±0.005 mm | Large prismatic blocks |
| Thin walls under 1 mm | 5-axis with light finishing passes | ±0.01 mm | Heavy roughing without support |
| Hardened steel above 45 HRC | 3-axis with carbide or CBN | ±0.01 mm | Soft-material feeds and speeds |
Quoting questions engineers ask
What information do I need before requesting a CNC quote?
Send the 2D PDF, the 3D STEP file, the material grade with temper or condition, the quantity per release and the finish callout. Add any inspection report requirement and the target date.
If a feature is still open, mark it on the drawing. A quote built on an unfinished drawing will be revised, and the second number is often higher.
Why do two shops quote very different prices for the same part?
They usually assumed different setups, tolerances or inspection levels. One shop may plan three setups on 3-axis machines; another may plan one 5-axis setup. Both can be valid, but they are not the same job.
Ask each supplier to list setups, tightest tolerance and inspection method. Once those match, the remaining gap is machine rate, overhead and margin.
Should I ask for a price break at higher quantities?
Yes, but ask for the volume bands you might actually order. A price at 10,000 parts is useless if your forecast is 300. Request 1, 10, 100 and 1,000 part pricing so you can see where the setup cost is absorbed.
Above roughly 1,000 parts, ask whether a dedicated fixture would reduce the unit price. The fixture cost may pay back within one or two releases.
How does surface finish affect the quote?
As-machined at Ra 1.6–3.2 μm comes from a normal finishing pass and adds little. Ra 0.8–1.6 μm needs a controlled finish pass with sharp tooling, which adds cycle time.
Below Ra 0.8 μm usually needs extra operations such as fine turning, lapping or polishing. On some geometries those operations are manual, so the cost is labor, not machine time.
What should I do if my quote comes back higher than expected?
Ask which feature drives the cost. It is usually one tight tolerance, one deep pocket or one finish callout. Then decide whether that feature can be relaxed without affecting function.
A second quote at looser tolerance on non-critical faces is a fair comparison. It shows the customer the cost of the tight call instead of arguing about the total.
Can a quote be issued before the design is frozen?
Yes, as a budget number. State clearly that it is based on the current revision and will be repriced after the design freeze. Budget quotes help with early cost targets.
Do not treat a budget quote as a firm price. Material, setup count and inspection scope can all change when the drawing changes.
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