FDM, SLA, SLS or MJF: choosing a 3D printing process for your part
Each process trades cost, strength, finish and volume differently. Here's how to pick one by what the part has to do, not by the name of the machine.
Protofab2 min read
Most people who send us a file ask the same first question: which process should I use? The honest answer is that it depends on what the part has to do. A model you'll hold in a meeting and a bracket that has to survive a vibration test need different things.
Start with the job, then pick the process.
If you just need to see and hold it
Use FDM. It's the cheapest and fastest way to check size, shape and fit. Parts are built from thermoplastics such as PLA, PETG and ABS, layer by layer, so you'll see the layer lines, but for a concept model that rarely matters.
FDM is also a good fit for jigs, fixtures and shop-floor aids, where ASA, nylon or TPU give you toughness and some flexibility.
If it has to look like the real product
Use SLA. Resin printing gives a smooth surface and fine detail, which is what you want for display models, presentation samples and master patterns. Clear and high-temperature resins are available when the part needs them.
If you need several copies that look and feel like production plastic, ask about vacuum casting: a silicone mould is made from a master, then cast in polyurethanes that mimic ABS, PP, rubber or clear plastics.
If it has to survive testing
Use SLS or MJF. Both fuse nylon powder (PA12, PA11 or glass-filled nylon) into strong, functional parts. Because the surrounding powder supports the part as it's built, there are no support marks, and complex shapes like snap fits and internal channels come out cleanly.
If you need tens or hundreds
Use MJF or vacuum casting. MJF is built for repeatability, so it suits end-use parts in short runs. Vacuum casting gives a production finish without the cost of an injection mould.
If the tolerances are tight
Use plastic machining. CNC machining from solid POM, PTFE, PEEK, nylon or HDPE gives the dimensional accuracy that printing can't always match.
At a glance
| Process | Best for | Strength | Finish | Volume |
|---|---|---|---|---|
| FDM | Functional prototypes | 4/5 | 3/5 | Low |
| SLA | Display models | 3/5 | 5/5 | Low |
| SLS | Functional parts | 5/5 | 4/5 | Medium |
| MJF | Production parts | 5/5 | 4/5 | High |
| Vacuum casting | Short production | 4/5 | 5/5 | Medium |
| Plastic machining | Precision parts | 5/5 | 5/5 | High |
Still not sure?
Send us the file with a sentence about what the part is for. We'll recommend a process and material and tell you why, before you pay for anything.