Does MJF Hold Up Better Than SLS for Small Gears in Continuous Mesh, or Is That Mostly Anecdotal?

MJF tends to do a little better for small gear teeth, mostly because of how the two processes finish a small feature, not because the base nylon is dramatically stronger. The difference is real but modest. It matters a lot less than tooth size, load, and duty cycle.

Where the difference actually comes from

SLS and MJF both print nylon powder into a solid part, but they fuse it differently. SLS sinters with a laser, point by point, which leaves a sandpaper-like surface texture on unsupported geometry. MJF jets a fusing agent across the whole layer and fuses with heat.

That generally produces a slightly finer surface and tighter dimensional repeatability, especially on small features like gear teeth that are only a few powder-particle-diameters thick at the tip.

For a small gear, tooth engagement is sensitive to surface roughness and to how close the as-built profile tracks the nominal one. MJF's finer finish and better small-feature accuracy translate into smoother mesh and somewhat less wear per cycle. That's the real mechanism behind the anecdotal reports. Bulk properties of SLS and MJF nylon are closer than the finish difference suggests.

Where the anecdote overstates it

Don't read too much into it.

None of that makes either process a substitute for a machined gear in a continuous-mesh application carrying real load. Both are printed nylon, with lower stiffness than metal and more prone to creep under sustained load. Neither holds a tooth profile anywhere near what you'd get off a hobbed or ground gear.

If the gear is decorative, low-cycle, or lightly loaded, either process is fine and MJF has a slight edge. If it's running continuously under meaningful torque, you're in machined-part territory regardless of which powder process you're comparing.

What actually determines gear life here

Tooth pitch, load, and cycle count matter far more than the MJF-versus-SLS choice. A coarse-pitch, lightly loaded gear will outlast a fine-pitch, heavily loaded one on either process by a wide margin. If you're choosing between the two for a real mechanical gear rather than a prototype fit check, lean MJF for the finish benefit, but don't expect it to turn a marginal design into a durable one.

DigiForge's 3D printing line runs industrial SLS and MJF in nylon and a handful of other materials, with a tolerance of ±0.3 mm or ±0.3% and a lead time of 5-7 business days. If the gear load is heavier than either process should take, that's a CNC part, and DigiForge runs both lines.