FDM and MJF are both excellent ways to make functional plastic parts, but they get there in very different ways. FDM lays down melted filament line by line to build each layer, while MJF fuses a full bed of nylon powder in a single pass. Knowing where each one shines saves you money and avoids the frustration of reprints that never quite work, especially when a deadline is close.
We run both at Global3D, with FDM printing and MJF & SLS printing under one roof in Perth, so we can be honest about which suits your part. The right answer often depends as much on quantity and finish as it does on raw strength, which is why a quick chat about the job usually points clearly to one process or the other.
Strength and direction
FDM parts are genuinely strong, but they are weaker across the layers than along them, so orientation on the bed matters a great deal to the result. MJF parts are close to isotropic, meaning they behave consistently no matter the direction of load. For parts that take force from several angles at once, MJF removes a lot of guesswork from the design and the testing that follows.
For large, simple, tough parts where the load direction is well known, a carefully oriented FDM part in an engineering grade material can be both strong and very economical. So strength alone does not decide the matter, the geometry and the loading pattern matter just as much, and sometimes an FDM part in the right filament is the smarter call.
Finish and detail
MJF gives a fine, uniform, grainy surface with no visible layer lines, and it captures small features and complex internal geometry cleanly. FDM shows its layers more openly and works best with larger features rather than tiny detail or intricate internal channels, though the right settings can tidy it up considerably.
For consumer facing housings, or parts with fine clips and channels, MJF usually looks and performs better straight off the machine. FDM can be sanded and finished to a high standard, but that adds hand work, whereas MJF often needs only a quick blast and dye to look the part.
Material choices
FDM gives you a wide menu of filaments, from tough PETG and ABS to engineering grades, and our Melbourne studio prints FDM up to 350 x 350 x 350mm in OzFDM filament for customers in Victoria. That breadth lets you tune stiffness, temperature resistance and cost to the job at hand.
MJF is more focused, running mostly PA12 nylon with a glass filled option for extra stiffness, all from our Perth warehouse. If your part needs a very specific material property, the filament range can sometimes match it more closely, so the material itself can guide the choice between the two processes.
Cost, size and volume
FDM wins on very large single parts and on one off items, since you only pay for the single part rather than filling a whole bed. MJF wins as quantities climb, because you can nest many parts into a single build and share the running cost across all of them, which drives the unit price down quickly once you order in sensible batches.
- Pick FDM for big single parts and quick one offs.
- Pick MJF for batches of small to medium parts.
- Pick MJF when finish and complex detail really matter.
- Pick FDM when budget on a single large item is key.
Not sure which to use
Tell us the quantity, the rough size and how the part will be used in service, and we will recommend FDM or MJF based on your real needs rather than a default. Send the model through and get a quote and we will lay out the options clearly, including the likely cost and lead time for each route.