For polymer production runs from a few dozen parts to a few thousand, three additive technologies dominate the conversation in Australia: FDM, SLS and MJF. Each has overlapping capability with the others, and each has a profile that suits a different combination of geometry, volume, material and budget.
This is not a contest with a winner. It is a decision framework, and the right answer routinely depends on details that are hard to see in a generic specification sheet.
FDM: predictable, flexible, affordable
FDM extrudes thermoplastic filament layer by layer. Its strengths are; lowest cost per part across most geometries, the widest material range of any process (every engineering thermoplastic, plus specialty composites and continuous fibre reinforcement), the largest build volumes available commercially, and the most predictable engineering behaviour for load-bearing work. Our largest cells reach 1m x 1m x 1m, with filaments from OzFDM covering the full spectrum from PLA to PA-CF. The trade-offs are; visible layer lines on as-printed surfaces, anisotropic mechanical properties with interlayer strength around sixty to eighty per cent of in-plane, and feature resolution that lags powder-bed processes.
SLS: strong, isotropic, premium
SLS sinters polymer powder with a laser, layer by layer, inside a heated chamber. The strengths are near-isotropic mechanical properties, no support material because the un-sintered powder bed carries the part, excellent fine-feature resolution, and clean engineering surfaces straight off the machine. Trade-offs are higher cost per part than FDM, a material range limited mostly to nylon variants, modest build volumes (typically a 300 to 400 millimetre cube), and powder-handling overheads at finishing.
MJF: production volumes at tight tolerances
MJF, Hewlett-Packard's Multi Jet Fusion, selectively fuses polymer powder under infrared lamps using a chemically deposited fusing agent. Its strengths are very high throughput, excellent dimensional repeatability, tight tolerances, and good surface finish straight out of the machine. Trade-offs are the highest equipment capital cost of the three (which limits the Australian supplier base), a narrower material catalogue than FDM, and a default part colour of grey or black that requires dyeing for any coloured cosmetic finish.
FDM: lowest cost, largest builds, widest materials
SLS: strong and isotropic, fine detail, no supports
MJF: production speed, tight tolerances, repeatable
FDM for large, structural, low-volume and one-off
SLS or MJF for complex geometry and higher volumes
How to choose for your run
If the part is large, structural, or made of a thermoplastic outside the nylon family, FDM is almost certainly the right answer. If it is smaller, has complex internal geometry, needs near-isotropic mechanical properties, or runs into the hundreds of identical units per batch, SLS or MJF should be on the shortlist. The most sophisticated assemblies often use both: FDM for the large structural parts, SLS or MJF for the fine detail items, integrated into a single product.
KEY TAKEAWAYS
FDM dominates large, structural and low-volume work
SLS delivers isotropic strength and fine detail without supports
MJF wins when volume and tight repeatability are the drivers
Multi-process workflows are now common for serious industrial products
Geometry, volume, material and budget all weigh into the decision