Process selection
How do you choose the right 3D printing process for a part?
Choose a 3D printing process by answering five questions in order: how big the part is, how much detail it needs, what load or heat it sees, whether it needs more than one material, and how many you need. Size decides first: parts over 350 mm go to FDM, which builds up to 1000 mm.
Reviewed by HenleyPrint3D engineers3 min readUpdated
Key takeaways
- Size first: over 350 mm means FDM.
- Then detail: fine features point to SLA.
- Then load: moving or snap-fit parts point to SLS nylon.
- If unsure, send the CAD. An engineer will confirm before printing.
Suits
Anyone with a CAD file and no preferred process yet.
Worth knowing
Size decides first: parts over 350 mm print on FDM, and SLS builds to 165 × 165 × 300 mm.
Five questions that decide the process
- How big is it? Over 350 mm: FDM (up to 1000 mm). Over 165 × 165 × 300 mm rules out SLS.
- How much detail? Walls under 1 mm or fine text: SLA (min wall 0.5 to 1.0 mm).
- What load or heat? Moving or snap-fit parts: SLS or FDM nylon. Heat over about 100 °C: industrial FDM.
- Do you need more than one material? Rigid plus soft: PolyJet. Soft only: TPU (FDM) or flexible resin (SLA).
- How many? Batches of small parts nest well in SLS. Large single parts go to FDM.
Best process by requirement
| Requirement | Best choice | Also works |
|---|---|---|
| Part over 350 mm | FDM | Split into sections for other processes |
| Fine detail, smooth surface | SLA | PolyJet, SLS |
| Functional, snap-fit | SLS | FDM nylon |
| Multiple materials in one part | PolyJet | TPU on FDM for a single soft material |
| Tightest standard tolerance (±0.1 mm minimum) | SLA | PolyJet, quoted per part |
| Lowest cost | FDM | SLS in batches |
Build volume, minimum wall and lead time by process
| Process | Build volume | Min wall | Lead time from |
|---|---|---|---|
| FDM | 1000 × 1000 × 1000 mm | 1.0 to 1.2 mm | 1 calendar day |
| SLA | 350 × 250 × 250 mm | 0.5 to 1.0 mm | 1 calendar day |
| SLS | 165 × 165 × 300 mm | 0.7 to 1.0 mm | 2 calendar days |
| PolyJet | Quoted per part | Quoted per part | Quoted per part |
For the full figures side by side, see FDM vs SLA vs SLS vs PolyJet. Each process has its own service page: FDM, SLA, SLS and PolyJet.
Frequently asked questions
How do I choose a 3D printing process?
Ask five questions in order: how big it is, how much detail it needs, what load or heat it sees, whether it needs more than one material, and how many you need. Each answer removes options until one process remains.
What is the best 3D printing process for functional parts?
SLS in nylon PA12 and FDM in engineering thermoplastics such as ABS, PETG, ASA or nylon are the usual choices. Resin processes are better for detail and appearance than for toughness.
Which process is best for small, detailed parts?
SLA is typically best for small, finely detailed parts, with resolution from 10 microns on our service. PolyJet suits parts that need several materials or colours.
Does the material or the process come first?
They are decided together. Material determines properties, and each process supports a different set of materials, so check that your required material is available in the process you prefer.
What information should I give for a quote?
Provide the CAD file, quantity, intended use, critical dimensions and any environmental conditions. The more we know about what the part must do, the better our process and material recommendation.
What is the cheapest 3D printing process?
FDM has the lowest cost per part of our processes. SLS becomes economical when many small parts share one build.
Get started
Talk to an engineer about your part.
Send us your CAD or describe the problem. We recommend the process, material and finish, and quote with the lead time up front.
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