Andrew Graves of Stratasys Direct Manufacturing, share’s an insider’s guide to the differences between stereolithography and PolyJet — the process, the build, size, speed, materials and more.

On the surface, it appears that stereolithography and PolyJet are identical twins. They both use UV energy to cure liquid photopolymer. But a closer look reveals they’re more fraternal than identical.

This article dives into stereolithography’s and PolyJet’s respective traits and offers tips on maximizing effectiveness for both processes.

PolyJet prints somewhat similar to a 2D printer, with fine print nozzles depositing plastic photopolymer droplets, coupled with water-soluble support material onto a clean build platform.  The plastic is simultaneously deposited by the print nozzles and cured with UV energy.  With layer resolutions of 0.00063 inches at its finest and 0.00118 inches for standard definition designs, PolyJet prints in the finest layer resolution of any 3D print technology.

Stratasys Objet 500 3D printer
Stratasys Objet 500

Stereolithography, also known as vat photopolymerization, 3D prints designs within a bed of liquid resin. After a thin layer of resin is evenly spread across the build platform, UV energy, directed by dynamic mirrors, cures a cross-section of the design to the build platform.  Stereolithography prints in fine layer thicknesses of around 0.002 inches at its smallest and 0.005 inches for designs without specific resolutions, and its parts are built in a “green state” — i.e. they are not fully cured during printing. After they are built, parts are cured in a UV oven once excess resin has been removed.

This detailed article goes on to describe the post-processing, part size and build speed, and how the materials each technology use are tailored to unique applications.

> Read more by Andrew Graves at, July 28, 2016

Using Photopolymers for Your 3D Printing Projects