Small-Batch CNC Machining

What sets the per-piece price on a small batch?

Part of the cost of a machined batch is paid once per run and part on every piece. Setup is the once-per-run part: the time from the last piece of the previous job to the first good piece of yours, spent gathering the documentation, assembling the cutting tools and measuring them (source 1). Material and the labor to cut each piece change with the quantity (source 2), so every piece pays for its own.

Spread across the batch, setup is a fixed cost divided by the quantity, and that share of the cost of a CNC machined part falls as the run grows (source 3): at 10 pieces each carries a tenth of the setup, at 100 a hundredth. On a large lot, setup can be a small part of the production run and the rest is running the parts (source 1). If a few pilot pieces have to prove the fit before the rest are made, order them as their own run; each run carries its own setup (source 1).

Which parts and processes can a small batch cover?

One piece on its own is a one-off, and a design still being revised is a prototype; a small batch is the run of the same part that follows, as small as you need with no minimum order. Batches are quoted in aluminum, steel, stainless, brass, titanium and plastics, in the common material grades. Other alloys and plastics quoted on request. Name the grade on the print.

Round parts in a small batch, such as shafts, pins and bushings, are turned (source 4). Long, slender ones can go to Swiss-type turning, where the tools cut just in front of a guide bushing that supports the bar, so the part has little chance to deflect or vibrate (source 5).

Batches that need a grinding or wire EDM step are quoted the same way: a pin ground to size, since grinding gives very accurate dimensions and cuts hardened steel (source 6), or a profile cut by wire EDM in hardened tool steel, the process used to make punches, tools and dies from hard metals (source 7). So is a discontinued part remade from a sample, with the measured model quoted as its own line. Rush 1-2 weeks applies to machined parts with no secondary operations. Heat treat, grinding, EDM and finishing add time, and the quote gives the real date.

What should a small-batch quote request include?

A STEP file with no drawing is quoted from the model to a ±0.005 in general tolerance, or the one your notes name. A fully dimensioned 2D PDF is quoted without a CAD line. On a drawing, machining tolerances go on the critical dimensions, and the title block’s default covers every dimension with no tolerance of its own (source 8).

A finish called out on the print is quoted with the part. Lead time starts at order approval. Put your need date in the part description and the quote answers it.

How does a repeat order work?

Put the drawing number and its revision on the PO. A drawing’s revision block lists its versions (source 8), and ASME Y14.35 sets the practice for identifying and recording each revision (source 9), so the revision letter says which set of dimensions applies. Reorders at the same revision: send the last quote or PO number and it’s requoted. If the print has changed since, say so and the quote follows the new revision. If a part doesn’t match the print, it’s remade or credited.

If the part will also run on your own machines, weigh a dedicated fixture plate against the volume it will see: its whole cost lands on the one part number it was made for, which is hard to justify on a job that won’t produce many parts (source 10).

Can a batch ship in releases, or as a kit of parts?

Yes. A blanket order is one purchase order that allows several delivery dates over a period, with release orders called off as needed until it is fulfilled (source 11). Blanket orders are quoted here; put the total and the release dates you expect in the request. Price, release schedule and lead time per release are set in the quote.

Different parts for one build can go on one order too: send the files in a ZIP and they quote as one job, shipped together or in stages as the build needs them. For machine builders putting together a full equipment build, that is one purchase order instead of one per part. Shipping is quoted as its own line, or ships on your carrier account.

Sources

All accessed 27 September 2026. Where a figure here differs from your print, the print governs.

1. Mike Lynch, "The Effect of Lot Size on Productivity", Modern Machine Shop, 21 December 2017, mmsonline.com/articles/the-effect-of-lot-size-on-productivity (what setup covers and that it happens once per production run; its share on very small and large lots).

2. Wikipedia, "Variable cost": en.wikipedia.org/wiki/Variable_cost (labor and raw materials change with quantity).

3. Wikipedia, "Average fixed cost": en.wikipedia.org/wiki/Average_fixed_cost (fixed cost divided by quantity, falling as quantity grows).

4. Wikipedia, "Turning": en.wikipedia.org/wiki/Turning (a nearly stationary tool cutting a rotating workpiece into straight, conical, curved or grooved shapes).

5. Wikipedia, "Metal lathe", section "Swiss-style lathe / Swiss turning center": en.wikipedia.org/wiki/Metal_lathe (tools in front of the guide bushing; slender parts held firmly with little deflection or vibration).

6. Wikipedia, "Grinding (abrasive cutting)": en.wikipedia.org/wiki/Grinding_(abrasive_cutting) (very accurate dimensions; hardened steels).

7. Wikipedia, "Electrical discharge machining": en.wikipedia.org/wiki/Electrical_discharge_machining (wire EDM for punches, tools and dies in hard metals).

8. Wikipedia, "Engineering drawing": en.wikipedia.org/wiki/Engineering_drawing (title-block default tolerances; the revisions block).

9. ASME Y14.35-2025, "Revision of Engineering Product Definition Datasets and Associated Documents": asme.org (identifying and recording revisions).

10. Michael C. Anderson, "Modular Fixturing Pros and Cons", Cutting Tool Engineering, 15 October 2017: ctemag.com (a dedicated fixture’s cost on one part number).

11. Wikipedia, "Blanket order": en.wikipedia.org/wiki/Blanket_order (one purchase order, several delivery dates, release orders).