CNC Quantity Price Breaks: Why Unit Cost Drops
CNC quantity price breaks come from setup, programming and fixtures spread over more parts. Why unit price falls fast at first, then flattens out.
Order one part and then ask for the price at ten, and the unit cost drops hard. CNC quantity price breaks aren't a discount for buying more. They're the fixed work on the job getting split across more parts.
How Many Parts Before a Fixture Pays Off?
It depends on how much time the fixture saves per part against what it costs to make. The same logic sets the whole quantity curve: fixed costs up front, divided by the number of parts.
Titans of CNC Machining asked this in How Many Parts Before a Fixture Pays Off?. The chapters walk through a custom fixture across two ops, then "Prototype VS Production Machining." That's the tradeoff every quote makes.
What Gets Split Across the Parts in CNC Quantity Price Breaks?
The fixed pieces of a machined part are the ones you pay once per job:
- Programming. The toolpaths are written once.
- Setup. Workholding, tool offsets and proving out the first part.
- Fixtures. Soft jaws or a custom fixture, if the part needs one.
- First article checks. See why first article inspection matters on low quantities.
Material and cycle time are paid on every part, so they don't shrink much. Boothroyd Dewhurst's machining cost estimator guide says it simply: "Batch size determines how much setup cost per part." Setup is amortized as total setup divided by batch size, so small batches carry a lot of it.
That's why the curve falls fast from one to a handful of parts, then flattens. Once setup is a small slice of each part, the unit price sits close to material plus machining time.
How Our Quote Handles Quantity
On our CNC quote, "Quantity breaks apply to the machining portion." The price is built from stock and material rate, setup and programming, machining time and each detected feature, so you can see which lines move when you change the quantity.
A couple of practical points:
- If you'll need ten, quote ten now. Ordering one at a time pays setup every time.
- Extra setups add fixed cost too. A part machined from four sides carries more of it, as in programming a 5-axis trunnion vs a 3-axis mill.
For the rest of what drives the total, see what actually drives the cost of a CNC quote.
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