How Much Do You Charge for CNC Machine Time?
CNC machine time is only part of a machining quote. The rate you pay is set by the machine class, the number of setups, the cycle time and how much inspection the part needs. This guide shows how to break a quote into those pieces and how to check whether the hourly figure you were given is realistic.
In this article
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Key takeaways
What the CNC machine time rate actually covers
Every machining quote has an hourly number in it. That number is not a shop's profit margin. It is a recovery rate: the shop is recovering the cost of the machine, the floor space, the operator, the tooling consumed during the run, and the engineering time spent planning the job. When you ask how much a shop charges for CNC machine time, you are asking about all of it at once.
The machine class sets the floor. A 3-axis mill cutting an ABS prototype and a simultaneous 5-axis center cutting a titanium bracket are both 'CNC machine time', but they recover very different costs. At GreatLight we run 127 high-precision CNC machines across three plants in Dongguan and Singapore, including 16 simultaneous 5-axis machining centers, 12 four-axis mills, 27 three-axis machines and 16 mill-turn centers. A rate that fits one of those machine classes will not fit another.
The part geometry sets the multiplier on top. Two parts with the same bounding box can differ by a factor of three in cycle time because of wall thickness, pocket depth, feature count and how many faces must be reached. A part with deep, narrow pockets forces smaller tools and slower feed rates. That is real machine time, and it shows up on the invoice.
So the useful question is not 'what is your hourly rate'. It is 'what work is inside that hour'. Once a quote is split into setup, cycle, tooling, finishing and inspection, the rate becomes checkable. You can compare two suppliers line by line instead of comparing two headline numbers.
The four drivers that move the number most
Setup count is the single largest lever on a low-volume job. A part that can be machined in one setup is far cheaper than one that needs three re-fixturings, manual rotations or a 4th axis index. Every extra setup adds load and unload time, a new work offset, a first-article check and the risk of stack-up error. On a 100-piece run, one avoided setup can remove hours from the quote.
Cycle time follows removed volume, not part size. A large thin-walled aluminum housing can be quick because there is little material to remove and the walls can be reached from two directions. A small hardened steel block with a deep 4 mm slot is slow because the tool must be small, the stepover is short and the spindle cannot push hard. Roughing removes the bulk; finishing is where tolerance and surface finish are set.
Tolerance and finish change both cycle time and inspection time. Holding ±0.005 mm (±0.0002 in) on a bearing bore means slower finishing passes, temperature-aware measurement and often a separate finishing operation. A general machined surface at Ra 1.6–3.2 μm is a normal milling result. Asking for Ra 0.2–0.8 μm adds polishing or a dedicated fine-finishing pass and its own handling.
Material and availability round it out. 6061-T6 and 303 stainless cut predictably and tool life is known. Inconel, Ti-6Al-4V and 17-4PH in a hardened condition cut slowly, consume carbide quickly and may need more frequent tool changes inside the cycle. If the bar or plate is not on the shelf, waiting time enters the schedule even if it never appears as a machine-hour line.
How to read a machining quote line by line
A useful quote separates at least five things: setup, cycle time, tooling and fixtures, finishing, and inspection. If a supplier sends one lump sum, ask for the split. A shop that cannot explain its own breakdown usually cannot defend its price either. The split also tells you where to aim a design change. If setup is 60 percent of the quote, simplify fixturing or reduce the number of machined faces.
Check the quantity break. On a one-off prototype, setup dominates and the per-part price looks high. On a 500-piece run, setup is amortized and cycle time dominates. If a supplier quotes the same per-part price at 1 piece and 500 pieces, the quote was not built from a real process plan. Ask for prices at two or three quantities so you can see where the curve flattens.
Check what is excluded. Deburring, edge breaks, masked anodizing, laser marking, certificates of conformance and third-party inspection are often separate lines. On a medical or automotive part these are not optional. It is better to see them in the quote than to discover them after the first article.
Finally, compare the same scope. Two quotes with different tolerances, different finishes or different inspection levels are not comparable. Normalize the drawing requirements first, then compare. That step alone resolves most price confusion before any negotiation starts.
Where buyers and designers lose money
The most common mistake is quoting a part before the design is frozen. Every revision after the first article re-opens setup, and the shop has to bill the rework. Freeze the geometry, then quote. If the design is still moving, prototype first and accept that the prototype rate is not the production rate.
The second is over-tolerancing. A bore called out at ±0.01 mm when the mating part only needs ±0.05 mm roughly doubles the finishing and inspection effort for no functional gain. Tolerance should come from the fit, not from habit. The same applies to surface finish: Ra 0.4 μm on a non-sealing face is money spent on nothing.
The third is ignoring the material form. A part designed from plate may be cheaper from bar stock at low volume, or the reverse at high volume, because of how much material must be removed. Tell the shop what form you expect and let them confirm. Material grade also matters: 304 stainless machines differently from 303, and 17-4PH in condition H900 is a different job from annealed.
The fourth is choosing on price per part alone. A quote that is 15 percent lower but adds a week of schedule risk, or that skips first-article inspection on a ±0.005 mm feature, is not cheaper. At GreatLight we quote with DFM feedback in 12 hours and can start production within 24 hours, so you can compare total cost including time, not just the hourly figure.
Step by step: how to estimate and check CNC machine time
- 11. Define the machining scope from the drawingList every toleranced feature, every surface finish callout and every face that must be machined. Mark which faces are datums. Anything not on this list should not appear in the quote.
- 22. Choose the machine class from part geometryOne or two reachable faces and simple pockets: 3-axis. Features on four sides: 4-axis or mill-turn. Complex contoured surfaces, deep angled features or five-sided access in one setup: 5-axis. Match the class before discussing rate.
- 33. Count the setupsFor each setup, note how the part is held and what the operator must do. Two setups is normal for a bracket. More than three usually means the design should be reviewed before quoting.
- 44. Estimate removed volume and cycle timeTake the stock bounding box, subtract the finished part volume, and estimate roughing at 60–75 percent of cycle time. Finishing is the rest. Multiply by quantity to get total cycle minutes.
- 55. Add inspection time and methodA ±0.1 mm part may need calipers only. A ±0.005 mm bore needs a CMM or a bore gauge with a known reference. Add the inspection minutes and any report preparation to the quote.
- 66. Request the quote at three quantitiesAsk for 1, 50 and 500 pieces, or the closest bands to your program. The shape of the price curve shows whether setup and cycle were priced realistically.
- 77. Compare normalized quotesPut setup, cycle, tooling, finishing and inspection in a table, one column per supplier. Compare the same scope. Ignore any quote that will not break the number down.
Machine class, typical work and what drives its rate
Rates vary by region, volume and material. Use the driver column to test a quote, not the class alone.
| Machine class | Typical work | Main rate driver |
|---|---|---|
| 3-axis mill | Plates, brackets, simple pockets | Fewest setups, shortest cycle |
| 4-axis mill | Four-sided parts, indexed features | Index time, fixture rigidity |
| 5-axis simultaneous | Contoured, five-sided, aerospace | Programming, machine hour, tool reach |
| Mill-turn | Shafts, bushings, turned-milled parts | One setup replaces two machines |
| EDM / wire | Sharp corners, hardened steel | Electrode or wire cost, slow cut |
| Surface finishing | Anodize, plating, bead blast | Batch size, masking, handling |
Frequently asked questions
Is there a standard hourly rate for CNC machine time?
There is no single standard rate. Shops publish bands, but the band depends on machine class, region, shift pattern and how much engineering is included. A 3-axis mill on aluminum and a 5-axis center on Inconel sit in different bands even at the same shop.
Use the published band only as a sanity check. The useful comparison is the full quote broken into setup, cycle, tooling, finishing and inspection.
Why is my one-off prototype per part price so high?
On a single part you pay for the whole setup, the full programming time, the first-article check and the tooling, with nothing to amortize them across. The machine hour is often a minority of the total.
Ask for the quote at 1, 50 and 500 pieces. If the per-part price drops steeply between 1 and 50, the quote was built correctly.
Does tolerance really change the price that much?
Yes, at both ends of the range. Tightening from ±0.1 mm to ±0.005 mm changes the cutting strategy, the measurement method and the number of accepted parts. Loosening a non-critical callout back to ±0.1 mm can cut finishing and inspection time noticeably.
Review every tolerance against the fit it serves before you send the drawing out.
How does quantity affect the quote?
Setup and programming are fixed costs. They spread across the batch. Cycle time, tooling and material scale with quantity. As quantity rises, the per-part price falls until setup is negligible, and after that it tracks cycle time and material cost.
There is no minimum order quantity at GreatLight, so prototypes and 10,000+ part runs both fit. The pricing logic is simply different at each end.
What should be listed separately in a machining quote?
Setup, cycle time, tooling and fixtures, finishing, inspection and any certification or report. Material should be its own line with grade and form. Freight and any masking or special packaging should be visible too.
If a supplier will not separate these, you cannot tell which part of the price is negotiable and which is fixed by the process.
Can design changes reduce CNC machine time?
Often, yes. Opening a deep pocket, adding a fillet radius that matches a standard cutter, keeping walls above about 1 mm, and reducing the number of machined faces all cut cycle time. Designing so the part can be held in one setup removes a whole setup cost.
Send the model for a DFM review before quoting. It costs nothing and usually finds one or two changes worth making.
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