What Is a Resin 3D Printer & How Does It Work?

Form 3

Most resin 3D printers are stereolithography (SLA) printers, which cure liquid resin layers with a laser rather than extruding plastic with a print head.

Because they are not restricted by the mechanical movements of a print head, resin 3D printers can produce models with greater complexity than Fused Filament Fabrication (FFF) 3D printers, albeit with a trade-off in outright speed.

Another resin technology suited to larger parts is Digital Light Processing (DLP), which uses UV light from a projector rather than a laser.

How does a resin printer work? This article explores the print process in more detail.

Let’s jump in!

What is a resin 3D printer?

An SLA resin 3D printer uses liquid resin as the build material, which it cures with a laser. The precise laser cures layers of liquid resin on the build platform. The printer uses galvanometers for X and Y positioning, with the laser passing through lenses and bouncing off mirrors for accurate layer positioning.

Formlabs factory

After each layer is printed, the printer’s tank moves, peeling the new layer off the surface of the resin tank. The build platform rises for the fresh resin to flow under the build platform for the next layer, and this process repeats until the model is complete.

With a DLP resin printer, the UV projector light source remains stationary, curing one large layer of resin at a time. DLP is better for producing large, one-off pieces, while SLA is better for printing several complex parts simultaneously.

How does resin 3D printing work?

Resin is a UV-curing liquid plastic that dries with UV light. The printer holds a vat of this photosensitive resin, and individual layers are hardened by a UV laser, fed by instructions in G-code produced by slicing software.

Small series production

The laser spot size determines the layer height, with fine detailing requiring a smaller spot size. When the laser hits the resin, it crystallizes and hardens instantly, becoming dense and rigid enough to support the next layer.

This process describes how every SLA 3D printer works, but Formlabs uses a more advanced version called Low Force Stereolithography (LFS).

Taking SLA to another level with LFS

SLA has a problem with peel forces – the forces exerted on parts during printing make supports challenging to remove. LFS addresses the peel force problem with a flexible resin tank and linear illumination.

Form 3

The flexible resin tank significantly reduces peel forces (the level of adhesion between layers and supports), creating light-touch supports.

Another advantage of LFS – and unique to Formlabs – is the closed optics engine called the Light Processing Unit (LPU). The LPU emits a clean laser spot, with a proprietary spatial filter to catch stray light and a series of mirrors, ensuring the beam is delivered perpendicular to the print plane for incredible accuracy.

Find out more

If you enjoyed this article, read our piece on preparing models for SLA printing.

For expert advice on 3D printer technologies, please get in touch with the team at 01765 694 007, email team@additive-x.com, or you can




Leave a Comment

Your email address will not be published. Required fields are marked *