CNC machined — aluminum sensor bracket
Aluminum 6061-T6 · 50 × 40 × 10 mm · 3-axis milled · 6 holes, 1 pocket · as-machined · ±0.1 mm general
$258 total
$435 total
$760 total
$1,725 total
$3,300 total
Cost drivers: CNC machining cost guide
Low-Volume Production
Low-volume production: 20–500 units, no tooling.
Prototype validated and you need a few hundred? Get production-grade CNC machined and sheet metal parts in batches, with the inspection reports and certificates your buyer asks for — quoted in minutes.
Keep machining, or tool up?
The only decision that changes the price by more than a few percent. Machining has no tool to pay off and lets the design keep moving; tooling wins on per-part price once the run is long enough to absorb it. For a rigid plastic part the lines cross at about 250 units. Metal parts stay machined or fabricated far longer.
| Run size | Recommended route | Typical lead time | Why |
|---|---|---|---|
| 20–50 units | CNC machining / sheet metal | ~7–10 business days | Setup is already amortized by unit 10; the design can still change between batches at no cost beyond the parts.Also consider: Urethane casting for soft or clear parts. |
| 50–250 units | CNC machining / sheet metal | ~2–3 weeks | Still cheaper than any tooled route for a rigid part — the $2,500 aluminum tool has not paid for itself yet.Also consider: Start quoting rapid tooling in parallel. |
| 250–500 units | Rapid aluminum tooling (plastics) | ~3–4 weeks incl. tool | Past the ≈250-unit crossover a molded part costs less all-in — but only if you are done changing it. Metal parts stay machined.Also consider: CNC if the design is not frozen or the part is metal. |
| 500+ units | Tooled production | 4–8 weeks | This is where per-part price, not flexibility, wins. See the injection molding cost guide for the steel-tool crossover.Also consider: CNC for metal; rapid → steel tooling at ≈4,000 units. |
Total program cost, 0–600 units — machining vs rapid tooling
CNC machiningUrethane castingRapid aluminum tool
Below ≈250 units CNC machining is cheaper because there is no tool to pay off; above it the $2,500 aluminum tool starts earning its keep. Urethane casting rises steepest — it competes on materials (soft, clear) and geometry, not on price for a rigid part. Cost functions: CNC $60 + $13.50/part · casting $400 + $47.50/part · rapid aluminum tool $2,500 + $3.50/part (palm-size rigid plastic housing, same assumptions as the injection molding cost guide).
Full tooling economics — rapid aluminum versus production steel, and the second crossover near 4,000 units — are in the injection molding cost guide. Cast metal parts follow the same logic at higher volumes; see the metal casting cost guide.
What a batch actually costs
Three reference parts priced through the FabDigit quote engine at low-volume quantities. The shape of every curve is the same: a big drop into 100 units, then a long flat tail — which is why splitting 500 into batches costs so little.
−26%
25 → 100 units is the big step
The bracket falls from $10.30 to $7.60 per part. Most of the remaining setup and fixturing cost is gone by unit 100.
−13%
100 → 500 barely moves
Only $7.60 → $6.60. Ordering 500 at once instead of 5 × 100 saves about $1 a part — and freezes a design you may still want to change.
~$1,000
A batch of 100 machined parts
Small aluminum brackets land around $760 per hundred; a palm-size machined enclosure around $2,400. No tooling line on the invoice.
CNC machined — electronics enclosure body
Aluminum 6061-T6 · 120 × 80 × 40 mm · deep pocketing, M3 tapped holes · bead blast · ±0.05 mm on bores
$800 total
$1,400 total
$2,400 total
$5,500 total
$10,500 total
Cost drivers: CNC machining cost guide
Sheet metal — steel mounting bracket
Mild steel · 2 mm · laser cut, 2 bends · 4 mounting holes
$240 total
$980 total
$3,600 total
Cost drivers: Sheet metal cost guide
CNC figures derive from the qty-100 prices published in the CNC machining cost guide and the quote engine’s own batch-decay ratios at 25 / 50 / 250 / 500, sampled in September 2026 for the exact reference geometry and rounded. Sheet metal figures are the sheet metal cost guide’s published points. Shown for comparison, not as a quote — your part is priced on its own geometry and confirmed by engineering review.
Inspection and certificates that ship with a batch
At 100 units the question stops being “does this part work” and becomes “can I prove every part matches.” These are the inspection levels and certificates in the FabDigit quote form — pick them with the quantity, and the reports arrive as signed PDFs with the parts.
| Inspection level | Cost | What you get | Use it when |
|---|---|---|---|
| Standard inspection | Included | In-process checks; final verification on critical features. No document ships. | Internal fixtures, brackets, non-critical parts. |
| Build and hold (first article) | $ | One part or a small batch ships first; the balance is held until you approve it. | First batch of a new design — catch a fit issue on 1 part, not 200. |
| Dimensional report | $ | Key dimensions from your drawing measured and delivered as a signed PDF. | Any part with a tolerance your assembly depends on. |
| CMM report | $$ | CMM-measured dimensional report — highest measurement confidence. | Bores, sealing faces, ±0.025 mm callouts, mating stacks. |
| First Article Inspection Report (AS9102) | $$$ | Full AS9102 FAIR package on the first article. | Aerospace, medical, or a customer PPAP-style approval gate. |
| Source inspection | $$$ | A quality representative verifies parts and paperwork before shipment. | Regulated programs or a first supplier qualification. |
Certificates available on any order:
| Certificate | Scope |
|---|---|
| Certificate of Conformance | released with the delivery |
| Material certification | mill cert, EN 10204 3.1 |
| Material traceability | heat / lot chain of custody |
| Hardware certification | inserts, fasteners, standoffs |
| US-melted material (DFARS) | on request |
| US-made material (domestic) | on request |
How a batch order runs, upload to reorder:
- Quote in minutes, confirmed in hours. Upload STEP (+ PDF for critical callouts), set the quantity, pick inspection and certificates in the same form. An engineer reviews DFM and confirms the price before release.
- First article, if you want one. Choose Build and hold: one part ships for your in-hand acceptance and the balance starts only after you approve.
- Batch production on one line. The full run is made on the same machine and fixture set so parts match each other, not just the drawing.
- Inspection at the level you chose. Reports are measured against your drawing and delivered as signed PDFs in your account, with the parts.
- Ship with paperwork. Packing slip on shipment, Certificate of Conformance on delivery, material certs where ordered — all in the project’s Documents panel.
- Reorder against the same files. Your project keeps the drawings, spec, and inspection plan. The next batch is a new quantity on the same package — not a new engineering conversation.
Design changes that pay off at 100 parts
A prototype forgives anything. A batch multiplies every decision by the quantity — material waste, inspection minutes, finish lot charges. Six changes that cut batch cost without changing what the part does.
- Freeze the datums, not the whole design. Keep the faces used for fixturing and inspection stable between revisions; change everything else freely and the batch price barely moves.
- Tolerance budget, not blanket tolerance. ±0.1 mm general with tight bands only on mating features. Every ±0.025 mm callout is measured on every part in a batch — that is inspection time × quantity.
- Design to stock sizes. A 10 mm plate part from 12 mm stock wastes 17% of the material on every one of 500 parts. Ask which stock thickness the quote assumes.
- Specify the finish like a batch, not a sample. For anodize or powder coat name the color standard, masking, and rack-mark locations. Lot charges amortize nicely at 100+; color drift between lots does not fix itself.
- Consolidate hardware into the sheet metal. PEM inserts, standoffs, and studs installed at the fabricator remove an assembly step from every unit — order them with the parts and ask for the hardware certification.
- Mark the dims that matter on the drawing. Flag 3–8 critical dimensions. That list becomes the sampling plan for the dimensional or CMM report and keeps inspection cost proportional.
Moving from a first prototype rather than a validated design? Start with prototype manufacturing — process choice and single-part pricing for v1.
Low-volume production — FAQ
What counts as low-volume production?
Roughly 20 to 500 units of a validated design — past the prototype stage but below the volume where injection molding or die casting tooling pays for itself. For rigid plastic parts the crossover from CNC machining to rapid aluminum tooling is about 250 units; metal parts typically stay machined or fabricated well beyond 500.
Is there a minimum order quantity?
No. FabDigit quotes from one part upward. Low-volume batches simply price lower per part because programming, fixturing, and first-piece inspection are spread across the run.
How much does a batch of 100 CNC machined parts cost?
A small aluminum bracket (50 × 40 × 10 mm, 6061-T6) sampled through the FabDigit quote engine prices at about $7.60 per part at 100 units — $760 for the batch — and $6.60 at 500. A palm-size machined aluminum enclosure runs about $24 per part at 100. Your part is priced on its own geometry; these are reference points, not quotes.
When should I switch from CNC machining to injection molding?
For a rigid plastic part, around 250 units: below that the machined part is cheaper all-in because there is no tool to amortize; above it a rapid aluminum tool (roughly $1,500–5,000) wins on total cost. Switch only when the design is frozen — a design change after tooling costs a tool, a design change before tooling costs nothing.
How long does a 100–500 unit run take?
Typically 2–3 weeks for 100–250 machined or sheet metal parts and 3–4 weeks for 500, plus 3–5 days for anodize, powder coat, or plating. Runs of 20–50 usually ship in 7–10 business days. The quote states the actual date for your part before you commit.
How do you keep parts consistent across a batch and between reorders?
A batch runs on one machine and fixture set, and the project keeps the same drawings, spec, and inspection plan for reorders. Add a dimensional or CMM report to get measured evidence on the critical dimensions, or Build and hold to approve a first article before the balance is made.
Which quality documents can ship with the parts?
Certificate of Conformance, material certification (EN 10204 3.1 mill cert), material heat/lot traceability, hardware certification, dimensional or CMM inspection reports, an AS9102 first article inspection report, and DFARS US-melted or domestic material on request. All are selected in the quote form and delivered as PDFs in your account.
Price your batch in minutes.
Upload CAD, set the quantity, choose inspection and certificates — and get an engineering-reviewed quote before you commit.