Defense CNC machining is built on documentation and repeatability. Defense and DoD buyers usually work from a controlled drawing, need DFARS-compliant material, and order in low quantities where each lot has to match the last. This guide covers what build-to-print work involves, how small-lot spares are priced, and how traceability and inspection close the loop on government and defense CNC parts.
DFARS Material and Domestic Sourcing
Defense contracts frequently invoke DFARS clauses that require specialty metals from qualified sources. We machine to DFARS-compliant, made-in-USA material and hold the paper trail behind it. Every lot ships with a certificate of conformance and, where required, mill test reports tied to the heat lot.
- Aluminum: 6061-T6 and 7075-T6 for housings, brackets, and fixtures
- Stainless: 304, 316, and 17-4 PH for hardware and load-bearing parts
- Alloy steel: 4140 and 4340 for shafts and structural components
- Titanium and nickel alloys: Ti-6Al-4V, Inconel 625 and 718 for high-demand parts
Build to Print
Build to print means we make the part exactly as the controlled drawing specifies, without redesign. That places the burden on process discipline: read the drawing and its GD&T, machine to the callouts, and prove conformance. What we need to quote and build cleanly:
- A dimensioned drawing with revision level and title block
- Material and specification callouts
- Finish and coating requirements
- Inspection requirements, including any first article or source inspection
- Marking and packaging requirements
We are SAM.gov and CAGE code registered, so we can transact directly on government and prime-contractor work. Learn more on our government and defense machining page.
Tolerances on Defense Parts
Defense drawings run the full range. Typical production tolerances:
- General features: +/-.005 in
- Fit and bearing diameters: +/-.001 in to +/-.0005 in
- Critical datums: +/-.0002 in to +/-.0005 in
- Surface finish: Ra 63 uin general, Ra 32 uin machined faces, Ra 16 uin sealing surfaces
Small-Lot Spares
Much of defense work is spares: quantities of 1 to 50, sometimes a single replacement for a legacy system. Small lots carry a different cost shape than production runs because setup and programming are spread across fewer parts. That is normal and expected. The way to control it is to reorder against a proven program, which removes most of the setup and proveout on subsequent lots.
Choosing the process by geometry keeps small-lot work efficient:
- Round parts, shafts, and fittings: CNC turning
- Housings, plates, and prismatic parts: CNC milling on horizontal machining centers
- Small-diameter pins and connectors: Swiss machining for parts under about 1.25 in diameter
Traceability and Inspection
Defense inspection expectations mirror aerospace. We hold a full chain from heat lot to finished part and support:
- First article inspection with a ballooned drawing and a numbered report
- In-process verification at defined frequencies
- Final CMM inspection on our Brown & Sharpe coordinate measuring machine
- Documentation package with material certs, inspection reports, and certificate of conformance
Our process controls are ISO 9001-aligned, which keeps calibration, revision control, and records consistent across repeat orders. See our inspection and quality page for the full flow.
Defense CNC Machining Cost Drivers
The table below shows typical illustrative estimates for a mid-complexity 4140 or stainless spare in a lot of 1 to 25 pieces. These are planning ranges, not binding quotes.
| Cost Driver | What It Covers | Typical Range |
|---|---|---|
| Setup | Programming, fixturing, first-piece proveout | $350 to $1,500 per setup |
| Material | Certified DFARS stock with drops | $10 to $120 per part |
| Machine time | Cycle time at shop rate | $20 to $55 per part |
| Finishing | Plating, coating, black oxide, passivate | $8 to $50 per part |
| Inspection | FAI plus CMM reporting and documentation | $200 to $700 per lot |
On a lot of one, setup and inspection dominate the per-part cost. On a reorder against a proven program, those lines drop sharply and material plus machine time carry the price.
Lead Times
Proven defense parts typically ship in 3 to 6 weeks. First articles add 1 to 2 weeks for the layout and documentation. Material lead time on specialty alloys can extend the schedule, so early release of the drawing helps.
Defense Machining in Canastota, New York
Wexmar runs turning, milling, and Swiss with in-house CMM inspection in Canastota, NY. We are SAM.gov and CAGE registered, machine DFARS-compliant made-in-USA material, and ship nationwide. Send your controlled drawing through our instant quote tool or review our machine list to confirm capacity for your part.