Guides / Cost
Where the Money Goes in an Aluminum Machining Quote
September 21, 2026 by The Alu CNC Parts editorial desk / how this is checked
Two shops quote the same drawing and the numbers come back 40% apart. Usually nobody is wrong. They are making different assumptions about stock size, setups and where the coating happens.
This is what sits inside an aluminum machining quote, roughly in the order it matters.
The fixed work, paid once per order
Before a single chip is cut somebody has to program the part, work out how to hold it, build or set the fixture, and run a first piece to prove the program.
On a one-off this is most of what you are paying for. On a run of two hundred it disappears into the background. It is the single biggest reason the unit price collapses over the first few dozen pieces and then barely moves.
It is also why re-ordering an identical part is cheaper than the first order. The program and the fixture already exist. Say so when you re-order, because a quote written from scratch will not assume it.
Cycle time
The time the part spends on the machine. Driven by how much metal has to come off, how fast it can be removed and how many tool changes the shape demands.
Aluminum helps here. It cuts several times faster than steel and tools last longer, which is why aluminum prototypes come back in days.
What slows it down is geometry. Deep narrow pockets need long thin tools that cannot take a heavy cut. Small internal corner radii force small cutters. An internal corner radius of 3 mm lets a shop use a larger, stiffer tool and take heavier passes. A 1 mm radius in that same corner means a small tool, a slow feed and several more passes for the same result.
Thin walls are the extreme case, where feed rates drop by half or more.
Stock, not the finished part
You pay for the block, not the part. A component that would clear 60 mm plate but is drawn from 80 mm carries both the extra material cost and the extra time spent removing it.
Two things help. Design to standard stock sizes, and check the stock size on the quote rather than only the price. A shop assuming the next size up will always look more expensive than one that did not.
The alloy premium
6061 is the baseline. 7075 and 2024 run two to three times the price per kilo. MIC-6 also carries a premium.
The premium lands on the starting block, so it hurts most on parts where most of the material ends up as swarf. Work out roughly what the block weighs, not what the part weighs, and you will know whether the alloy is a small line or the largest one.
Tolerance, inspection and finish
Every tolerance band tighter than necessary pulls in a slower pass, a different tool or an extra step.
The part people underestimate is inspection. A general dimension might be checked on one part in ten. A ±0.013 mm bore gets measured on every piece, and that time is in your price whether the quote breaks it out or not.
Surface finish behaves the same way. Ra 1.6 um is what a normal finishing pass produces and costs nothing extra. Ra 0.4 um is a separate strategy.
Coating, and its batch minimums
Anodizing, chem film and powder coat almost always go to a specialist vendor with a minimum charge per batch.
On ten small parts that minimum can exceed the machining cost. This catches people out constantly on prototypes. Ask what the finish adds before committing to it, and on low quantities consider whether chem film or bead blast would do the job for less.
Masking is hand work and does not get cheaper in quantity, so a part with a dozen masked features carries that cost on every piece.
Quantity
Fixed work spreads over more parts, material gets bought in better sizes, and the shop can run the job with less attention per piece. The unit price falls steeply over the first few dozen pieces and then settles.
If you know you need forty parts this year, quote forty now rather than ten four times. You will pay the setup once instead of four times.
What a buyer actually controls
Three of the seven items above are decided on your drawing rather than in the shop: stock size, alloy and tolerance. Those are where the savings are, and none of them require negotiating.
Sources
Figures in this guide are checked against the following. Published values are typical ranges for test material, not a guarantee for your part.
Frequently asked questions
Why is one piece so expensive compared to fifty?
Programming, fixturing and the first proving cut are paid once whether you order one part or five hundred. On a single piece that fixed work is most of the price. Spread across fifty it becomes a small share, which is why the unit price falls steeply over the first few dozen parts and then flattens out.
Can I cut cost by supplying my own material?
Occasionally, but less often than people expect. Shops buy at trade prices and handle certification and traceability. Supplying your own stock also moves responsibility for the material onto you, so if a bar turns out to be the wrong temper the scrapped part is your problem. It is usually better to relax the alloy or the stock size instead.
Is a rush order worth paying for?
Sometimes. A rush premium buys you a place at the front of a queue, which is real value if the part is holding up something expensive. What it cannot buy is a shorter anodizing cycle or faster material delivery, so ask what is actually being accelerated before you pay for it.
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