CNC Machining Services Pricelist: What Actually Drives Your Quote

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  Key takeaways
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  How Each Variable Moves the Price
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  Why Tolerance Sets the Floor of Your Quote
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  Material Choice Changes Cycle Time, Not Just Stock Price
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  Quantity, Setups and the Point Where Method Changes
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  Finishing and Inspection Lines You Should Expect
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  Step by Step: How to Compare Two CNC Quotes

Tolerance is the first thing a shop reads on your drawing, because it decides how many operations the part needs. A bracket held to ISO 2768-medium can often be finished in two setups on a 3-axis machine, with the operator checking a few key dimensions with calipers. Nothing about that process is slow.

Tighten a bore to ±0.005 mm and the same part changes character. The shop now plans for thermal drift, tool wear and fixture stiffness. It may need a temperature-controlled area, a dedicated boring cycle at reduced feed, and an in-process probe check before the part leaves the machine. Cycle time can climb 2-4× on the tight features alone.

The trap is over-tolerancing. Engineers sometimes apply ±0.01 mm across an entire drawing out of habit, when only two mating bores actually need it. If you mark the functional dimensions and leave the rest at general tolerance, quotes usually drop without any loss of function.

Surface finish follows the same logic. Ra 3.2 μm comes off the machine with a normal finishing pass. Ra 0.2-0.8 μm needs slower feeds, sharper tooling and often a secondary operation. Ask whether the finish is cosmetic or sealing-critical before you specify it everywhere.

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  Mark functional dimensionsOnly the features that mate or seal need tight tolerance.
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  Give a datum schemeClear datums reduce setup count and disagreement at inspection.
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  State units and standardISO 2768 or ASME Y14.5, not both on one drawing.

Buyers often compare material by kilogram and stop there. That misses most of the cost. Aluminium 6061 machines at high spindle speeds with light cutting forces, so a shop can remove metal fast and hold tolerance with standard tooling. Stainless 316 work-hardens under a dull cutter, so feeds and speeds must be conservative and tools changed more often.

Titanium TC4 (Ti-6Al-4V) and Inconel sit at the far end. They cut slowly, generate heat at the edge, and wear tools quickly. On the same geometry, cycle time can be 3-8× the aluminium number, and the raw bar costs several times more per kilogram. Choosing titanium for a part that sees no heat or corrosion load is an expensive habit.

Stock form matters too. A part cut from near-net bar stock wastes less material than one carved from a thick plate. If your design allows, tell the shop which faces are cosmetic, so they can pick the stock size that removes the least metal.

Plastics behave differently again. POM and PEEK hold tolerance well but move with temperature, and thin walls can deflect under clamping. For prototypes in ABS or PC, a 3D printed or vacuum cast route may cost less than machining, while still proving fit.

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  Match material to loadUse titanium and Inconel only where temperature or corrosion demands it.
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  Consider near-net stockExtrusion or casting blanks cut machining time on large parts.
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  Watch thin wallsBelow 1 mm in plastics, clamping pressure becomes a tolerance risk.

A single prototype and a 10,000-part run are not the same process with a different number attached. At low volume, setup time is spread over few parts, so the shop optimizes for fewer setups and accepts longer cycle times. At high volume, it pays to build a fixture, split the part across two machines, or move to a mill-turn center that completes both sides in one clamping.

That crossover usually appears somewhere between a few hundred and a few thousand parts, depending on geometry. Below it, tooling investment does not pay back. Above it, unit price can fall 40-70% against the prototype figure. A good quote will show whether fixture cost is amortized or billed once.

Batch size also affects material purchasing. A shop buying one bar pays a cut charge. A shop buying a full length gets a better rate and less waste, but only if the order justifies it. If your program is annual, say so. It changes how the supplier buys.

For prototypes, there is no minimum order quantity at GreatLight. One part is a valid order, and the same DFM review applies whether the run is one piece or ten thousand.

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  Ask about the crossoverRequest unit price at 1, 100 and 1,000 pieces to see the curve.
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  Separate one-time and per-part costFixtures and programming should be visible as their own line.
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  Share the annual forecastIt affects material buying even if the first order is small.

Finishing is quoted per part and often carries a minimum batch charge, because anodizing tanks and plating lines run economically only above a certain load. Clear anodizing on a small aluminium bracket is inexpensive at volume but can cost more than the machining on a single piece, simply because the batch minimum applies.

Hardcoat anodizing, electroless nickel and bead blasting each add their own step and their own handling risk. Masking threads or sealing faces takes labor. If a finish is cosmetic only, say so. If it protects a sliding surface, specify the thickness range and let the shop choose the process window.

Inspection scales the same way. A sample check on a bracket is quick. A 100% inspection with a dimensional report on every part adds 5-15% and needs to be planned into the schedule, not bolted on at the end. For medical and aerospace parts, that report is usually not optional.

Laser marking is a small line but worth mentioning early. Minimum character height is 1.5 mm, and marking after anodizing looks different from marking before it. Decide the sequence before the first part runs.

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  Flag batch minimums
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  Specify finish by functionCosmetic, wear or corrosion, each points to a different process.
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  Request reports up frontInspection level changes both price and lead time.