Stereolithography (SLA) uses an ultraviolet laser that draws on the surface of liquid thermoset resin to create thousands of thin layers until the final part is formed. Support structures must be removed manually, and the parts are cured with UV light.

Selective laser sintering (SLS) uses a CO2 laser that lightly fuses nylon-based powder layer by layer to create a part. After printing, parts must be broken out of the powder bed, brushed to remove loose powder, then bead-blasted to remove remaining residual powder.

Multi Jet Fusion (MJF) applies fusing and detailing agents with an inkjet array across a bed of nylon powder. It uses heating elements to fuse the agents and nylon powder in thousands of layers into a solid part. After printing, parts are moved with the powder bed to a station where loose powder is removed by a vacuum. Then, the parts are bead-blasted.

PolyJet is a process in which small droplets of liquid photopolymer are sprayed from multiple jets onto a build platform where they are instantly UV-cured in layers that form elastomeric parts. After printing, the parts must be exposed to a pressurized water stream and chemical bath to remove support material. No post-curing is required.

Direct metal laser sintering (DMLS) uses a fiber-laser system that draws on a surface of atomized metal powder, welding the powder layer by layer into dense metal parts. Parts from the printer are brushed to remove most loose powder, put through a heat-treat cycle, removed from the support system and bead-blasted.

Ron Shinn, editor

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