Which process fits your part?
| Factor | 3D Printing (SLA / SLS / FDM) | CNC Machining |
|---|---|---|
| Best for | Complex geometry, internal channels, organic shapes, thin walls | Load-bearing parts, tight tolerances, production metals |
| Typical tolerance | SLA ±0.1 mm · SLS ±0.2 mm | ±0.05 mm on metal & engineering plastic |
| Materials | Resin, nylon (PA12/PA11/TPU), ABS/PLA | Aluminum, steel, brass, engineering plastics |
| Lead time | 1–3 days, no fixture setup | 2–4 days, programming + fixturing |
| One-off cost | Usually lower (no setup cost) | Higher per part at qty 1 |
| Batch consistency | Good, varies slightly across a run | Excellent, repeatable to tight limits |
Need 20–100 copies of a validated design? See our vacuum casting vs CNC guide for the small-batch path.
Use this 4-step checklist
1. Geometry wins on 3D printing
Internal channels, organic shapes, thin walls, and assemblies you can't fixture for milling — SLA/SLS gets there in one build. CNC would need specialty cutters or simply can't reach.
2. Strength & tolerance win on CNC
Load-bearing brackets, threaded inserts, parts needing ±0.05 mm, and anything going into a test rig — machined aluminum or steel is the safe call.
3. Quantity & speed break the tie
One urgent part tomorrow? Print it. Twenty identical housings next week? CNC — or vacuum casting if you want printed-part freedom with molded consistency.
4. Ask for a dual-process quote
The right answer is almost never "always print" or "always CNC." Send the STEP file and ask which process fits this part. See our FAQ for the files we need.
Where each process pulls ahead
SLA resin
Smooth, detailed masters for visual models, enclosures and electroplating. Best surface finish of any 3D process. See our 3D printing service.
SLS nylon
Strong, slightly porous, support-free parts for snap-fits, brackets and end-use components in PA12/PA11/TPU.
CNC metal & plastic
The choice for threads, mating features and load paths. Holds ±0.05 mm and takes real aluminum, steel and brass.
Common questions
Choose 3D printing (SLA/SLS) when the part has complex internal geometry, organic shapes, thin walls, or features that are hard to fixture for milling. Choose CNC when the part must carry load, hold tight tolerances (around ±0.05 mm), or use production metals.
CNC machining typically holds ±0.05 mm on metals and engineering plastics. SLA resin printing reaches about ±0.1 mm, and SLS nylon about ±0.2 mm. For threaded inserts and mating features, CNC is the safer call.
For a single urgent part, 3D printing is usually faster from file to part — often 1–3 days with no fixture setup. CNC needs programming and fixturing, so a simple part may take 2–4 days.
For one-off complex parts, 3D printing is usually cheaper because there is no fixture or setup cost. For several identical metal parts, CNC can become cheaper per unit. We recommend a dual-process quote to compare for your exact geometry.
Yes. A common workflow prints a master pattern and then CNC-machines critical surfaces or bores to tight tolerance, then finishes it. This hybrid gives printed geometry with machined accuracy where it matters.
Send a STEP, IGES, STL or native SolidWorks file, plus quantity, target material and required finish. We return a quote and, when useful, a recommendation of printing vs machining for that specific part.