MJF and SLS are close cousins. Both build parts by fusing nylon powder layer by layer with no support structures, and both produce strong, functional components in PA12. The differences between them are real but subtle, and the right pick depends on what matters most for your particular part rather than on one process being better overall. Finish, detail, colour and quantity all pull the decision in slightly different directions.
We run both as part of our MJF & SLS printing service in Perth, so we can match the process to the job rather than forcing every part down one path. Having both under one roof means our advice is genuinely about your needs, not about keeping a single machine busy, and we can switch between them as your volumes and finish requirements change.
How they fuse the powder
SLS uses a laser to trace and sinter each cross section, melting the powder exactly along the path of the focused beam. MJF instead jets a fusing agent across the whole layer and then uses infrared lamps to fuse everything at once. That difference in method drives most of the practical contrasts you will notice between the two finished parts, from speed to surface texture.
Because MJF fuses a complete layer in a single pass, it often prints a packed bed faster than a laser tracing every outline one by one. SLS, with its precise beam, can hold very fine detail in certain features, and it has decades of refinement behind it across a wide range of nylon grades, so it remains a trusted choice for demanding work.
Finish, colour and consistency
MJF parts come out a uniform grey and dye to a deep, even black very nicely, which many customers prefer for consumer facing products where appearance counts. SLS parts are typically a natural white with a slightly more matte, porous surface that some applications actually prefer, particularly where a part will be painted or left in its natural state.
MJF tends to give more consistent density and mechanical properties across a build, which helps when every part in a batch must behave identically. SLS, meanwhile, is extremely well understood and has a long track record across aerospace, medical and industrial work, so it is far from second best and still leads in plenty of niches.
Cost and lead time
On cost, the two processes are usually close, but the balance shifts with quantity and packing. MJF often edges ahead on densely nested batches of small to medium parts, because fusing a full layer at once spreads the running cost efficiently across many pieces in the same build.
Lead time tends to follow the same pattern, with MJF turning around full beds quickly and SLS holding its own on parts that need its particular detail. For most jobs the difference is small, so finish and feel often matter more than a day either way when you come to choose between them.
Choosing for your part
Neither process is universally better, and the best choice usually comes down to finish, detail, volume and the exact look you are after. A short conversation about the application normally settles it quickly, and sometimes the difference in cost or lead time makes the decision for you without much debate at all.
- Choose MJF for a fine, consistent finish and easy black dyeing.
- Choose MJF for fast, dense, small batch production runs.
- Choose SLS for certain fine features and established white nylon.
- Send the part through and we will recommend the better fit.
Let us help you decide
If you are unsure, that is completely normal, and it is exactly what we are here for. Send your model through and get a quote, or contact us with a few questions about the application, and we will tell you honestly which nylon process will serve your part best and why.