Top 4 Differences Between Stereolithography and PolyJet

Stereolithography and PolyJet are 3D printing processes that use photopolymer materials to additively build detailed prototypes. Both processes utilize UV energy to cure plastics, however their differing build styles separate them in terms of materials and applications. Knowing the differences will lead you to the best process choice for your project. Here are the top four differences between PolyJet and Stereolithography.
polyjet

Build Style

Stereolithography uses UV lasers directed via dynamic mirrors onto a bed of liquid plastic to cure patterns, cross-section by cross-section. PolyJet uses multiple print heads to deposit liquid plastic onto a clean build platform layer by layer. The material is cured as it is deposited. PolyJet can deposit material in layers as fine as 16 microns. Stereolithography prints in 0.002” layers at its finest. PolyJet is the fastest 3D printing technology for parts within a 5” cube. Outside of 5”, PolyJet becomes slower because the print nozzle has farther to travel while laying out an incredibly thin layer. In contrast, size doesn’t make a difference to Stereolithography; its rapidly moving mirrors sprint light across the build to cure designs.

 

polyjet 

 

Post-processing

Stereolithography and PolyJet both require support material to ensure accuracy, anchor parts to the build platform and aid the creation of delicate, overhanging features. Stereolithography supports are created out of the same material as the final part and must be sanded and removed by hand. Stereolithography parts are not built fully cured in order to drain out excess resin, and therefore (aside from support removal) they require additional curing in a UV oven. PolyJet parts are built fully cured. PolyJet supports are created out of a separate material specially formulated to release from the final part with water blasting and some hand labor. While PolyJet parts offer a smoother surface right off the build, Stereolithography parts offer a much easier to sand surface.

 

stereolithography

Stereolithography part as it rises from the build with visible supports still attached.

 

Materials

Given their reliance on UV light to solidify liquid resin, resulting PolyJet and Stereolithography parts are susceptible to light and heat degradation over their lifespan. Therefore regardless of material, neither process is ideal for functional or rugged prototyping or testing. Stereolithography materials are available in rigid clear, grey and white opaque as well as a specially formulated plastic for investment casting patterns. PolyJet materials come in all colors, opaque and transparent, as we as flexible and rigid. PolyJet is one of the only 3D printing technologies to print in rigid and flexible multi-color parts simultaneously for fast over-molded parts.

 

Ideal-applications


The speed and fine resolution of PolyJet make it ideal for small, highly detailed prototypes and master patterns. Stereolithography is a better fit for large prototypes and master patterns. One key advantage Stereolithography offers is an ability to print mostly hollow parts using an interior honeycomb structure. This honeycomb structure involves a thicker outer shell and an interior matrix for support. Stereolithography hollow parts are used in investment casting as one-off, complicated patterns lost wax patterns cannot imitate due to lost wax’s reliance on tooling. PolyJet’s key advantage is multi-material (or hybrid) printing. PolyJet printing can deliver durometer shore hardness ranges from 20-90A within a single build. Over-mold, elastomeric, and soft touch quick turn prototypes are ideal for PolyJet.

Snapshot: PolyJet vs. Stereolithography


Stereolithography PolyJet
UV Curable UV Curable
Support Removal: Hand sanding, light bead blasting      Support Removal: Water blasting, some residue removal by hand
Good Resolution at 0.005-0.002” Excellent Resolution at 0.00063”
Large Models and Patterns Small Detailed Prototypes and Patterns
Rigid opaque materials Rigid, opaque, multi-color, transparent and flexible materials

 

Stereolithography and PolyJet are both excellent choices for master patterns, prototypes and models. Read more about how Stereolithography and PolyJet factor into medical, aerospace and consumer products through our Case Studies page.

To learn more about 3D printing process and materials, download our materials guide: Choosing the Right Material for Your Application.

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