Get CNC Processing Quote Now: What Actually Drives the Price

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  Key takeaways
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  Why the same part gets different numbers from different shops
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  Geometry and tolerance: the two biggest levers
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  Material grade and surface finish costs
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  Volume, setup and the economics of a run
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  What to check before you request a quote
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  Which cost driver dominates your part

A CNC quote is not a single price. It is a stack of estimated times: programming, fixturing, roughing, finishing, deburring, inspection and any outside finishing. Each shop weights those times by the machines it owns and the tolerance it is comfortable holding. That is why two shops can look at the same STEP file and return numbers that differ by 40 percent.

When you get CNC processing quote now from GreatLight, the estimator reads the drawing for the tightest tolerance on the part, not the title-block tolerance. A single Ø 6 H7 bore on an otherwise loose bracket can pull the whole job onto a different machine and a different inspection plan. If that bore is not functional, loosening it is the fastest way to cut cost.

The second thing the estimator looks at is how the part is held. A prismatic block that sits flat in a vise is cheap to fixture. A thin-walled housing that deflects under clamping force needs soft jaws, support material or a custom fixture. Fixture time is paid once per order, but on a five-piece run it dominates the price.

Finally, the quote assumes a material condition. Bar stock, plate and near-net forgings carry different removal volumes and different scrap rates. If your drawing says 7075 but the part is not flying, 6061 machines roughly twice as fast and usually costs less.

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  Draw tolerance where it mattersApply tight limits to functional surfaces only; leave cosmetic faces at general tolerance.
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  Say how the part is heldNote any surface that must not be marred by clamping.
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  Name the material grade and temper6061-T6 and 6061-O machine very differently.

Removal volume sets roughing time, and roughing time scales almost linearly with the material you cut away. A part machined from a 20 mm plate with a 12 mm finished thickness wastes 40 percent of the stock. Swapping to a 12.5 mm plate removes that waste and shortens the cycle before any finishing tool touches the part.

Tool reach is the quieter cost. A pocket is cheap when its depth is less than three times the corner radius, because a stubby tool can cut it fast. Push the depth-to-diameter ratio past 5:1 and the tool must be necked down, run at lower feed and make multiple step-downs. Chatter risk rises, so the machinist may need a second finishing pass.

Tolerance is the second lever. Standard machining holds ±0.05 mm without special effort. Moving to ±0.005 mm means temperature-controlled finishing, on-machine probing or CMM verification, and sometimes a second setup to avoid tolerance stack between operations. The cost jump is stepwise, not gradual, so always ask what the next looser band would save.

Surface finish follows tolerance. Ra 3.2 μm comes off the machine. Ra 0.8 μm usually needs a finishing pass with a smaller stepover, and Ra 0.2 μm may need lapping or polishing after machining. If the finish is only cosmetic, bead blasting can hide tool marks at a fraction of the cost of a fine finish cut.

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  Keep pocket depth under 3× corner radiusDeep narrow pockets are the most common hidden cost in a quote.
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  Avoid sharp internal cornersA 1 mm corner radius forces a 2 mm cutter at best; 3 mm radii open up tool choices.
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  Tighten tolerance on one datum, not the whole partStacked tight tolerances multiply inspection time.

Material price is visible on the invoice, but machinability is where the money hides. Aluminium 6061 cuts at high speed with good chip evacuation. Stainless 316 work-hardens under a rubbing tool, so feeds must stay above a threshold and tools wear faster. Titanium TC4 (Ti-6Al-4V) conducts heat poorly, so the cutting edge runs hot and speeds drop sharply.

Special alloys change the whole plan. Inconel and magnesium AZ31B need specific tooling and, for magnesium, strict chip handling. If your application only needs corrosion resistance, 17-4PH stainless is far easier to machine than Inconel and often meets the same requirement. Name the grade, temper and any heat treatment on the drawing.

Finishing is priced as a separate line, and it usually sets the final ship date. Anodizing a batch may take a few days at an outside processor, and hardcoat or conductive anodizing adds masking steps. Electroless nickel and zinc plating follow similar outside schedules. Powder coating and black oxide are quicker but cover dimensions, so mask any bore that must stay within tolerance.

Laser marking is often the last step. Minimum character height is 1.5 mm, so a part number with 20 characters needs a clear flat area. If the marking area is a curved or anodized surface, contrast changes and the estimator may add a masking operation.

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  Match grade to functionDo not pay for Inconel if 17-4PH meets the load and corrosion case.
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  State heat treatment before machiningHardened stock changes tool selection and speeds.
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  Call out masking zonesThreads and bearing bores usually must stay uncoated.

Setup is a fixed cost. Programming, fixture building and first-article inspection do not shrink when you order five parts instead of fifty. On a one-off prototype, setup can be more than half the quote. On a 500-piece run it fades into the background, and the price per part approaches the cycle time plus material.

That is why a quote for one piece rarely predicts the price for one hundred. If you plan to scale, tell the estimator the target annual volume. It changes the fixture design, the decision to use a bar feeder, and whether a second operation should be moved onto a mill-turn center instead of a separate lathe and mill.

Batch size also affects inspection. One hundred percent inspection before shipment is standard at GreatLight, but the sampling plan and the report format depend on volume and on the industry. Medical and automotive work usually needs documented dimensional reports; a general industrial bracket may only need a first-article report.

Finally, lead time is not linear in volume. Production can start within 24 hours of a released order, and parts typically ship in 3–5 days for moderate quantities. Large runs or outside finishing push that out. If a date is critical, say so at quote time rather than after the order.

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  Give the annual volume, not just the first orderIt changes fixture design and machine choice.
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  Ask for a price break tableQuotes at 1, 10, 100 and 1,000 pieces show where setup stops dominating.
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  Flag the critical date earlyOutside finishing is the usual bottleneck.

Send a 3D model and a 2D drawing that agree. If the STEP file and the PDF disagree on a hole size, the estimator must stop and ask, and that delay shows up in your turnaround. A drawing with a clear title block, material, finish and revision is worth more than a perfect model alone.

State the function of the tight features. An estimator who knows a bore is a bearing seat will hold the tolerance and price the inspection. An estimator who does not know may assume the whole part needs that band and quote high. Two sentences of context can change a number.

Mention quantities and target dates. A quote for one piece is a prototyping quote; a quote for 500 is a production quote with a different fixture and a different inspection plan. Giving both numbers lets the estimator show you the crossover point.

If the design is not final, say so. Free DFM analysis within 12 hours is most useful when it arrives before the toolpath is written. We flag deep pockets, thin walls, un-machinable corners and tolerance stacks, then suggest changes you can accept or reject.

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  One revision number on every fileMixed revisions are the most common cause of a re-quote.
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  Mark functional surfacesA note like 'bearing seat, do not touch' prevents over-machining.
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  Include the finish specification standardName the standard and the color, not just 'anodize'.