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Stereolithography (SLA)

What is Stereolithography?

Stereolithography, or SL, is the process of converting a liquid plastic into solid 3-dimensional objects using a stereolithograph apparatus, or SLA machine. It was founded by Chuck Hull and 3D Systems back in 1986. The process and machine are most commonly referred to as SLA.

In August of 1996, TTH started running its first 3D printer, an SLA 500 Machine. As one of the first SLA prototyping service bureaus in Northeast Ohio and the USA, TTH has supplied tens of thousands of SLA prototypes to designers, marketers, engineers and entrepreneurs over the last 20+ years.

All SLA machines have interchangeable material vats that make it easy to change and run any material. SLA machines run 24/7 and are connected to provide real time status to AM technicians. This flexibility allows the ability to turn projects around in 1 day.

Most SLA parts are used for fit and function prototypes, master patterns, templates or marketing samples. The SLA process can be used for testing and production under the right conditions.

How does SLA work?

SLA builds a 3D model of a component using a vat of liquid ultraviolet-curable photopolymer resin and an ultraviolet laser to form one thin layer at a time, usually between 0.002”-0.006” or 50-150 microns. The laser beam traces a cross-section of the model on the surface of the liquid resin for each layer. Exposure to the ultraviolet laser light cures and solidifies the pattern traced on the resin and joins it to the layer below. After the pattern has been traced, the SLA machine’s elevator platform is lowered by the thickness of a single layer and the process is repeated. After an SLA is printed, we remove the excess resin and cure the component in an ultraviolet oven.

SLA Process

SLA Advantages

  • Highly Accurate
  • High Quality Finish with Fine Details
  • Ease of Finish, Paint and Bonding
  • Quick Cast and Master Patterns for Casting
  • No Size limitation – Section and Bond Large Parts Together
  • Economy of Scale

SLA Equipment

Large Frame SLA Machine

SLA Machine

These SLA printers have large build platforms of 20” x 20” x 11” (500mm x 500mm x 280mm) and build parts between 0.004”-0.006” (100-150 micron) layers depending on the material chosen. These machines can run at 0.002” for finer details and accuracy but are not used for this often. These are great for building large prototypes or loading up lots of smaller parts.

High Resolution Viper Machine

This SLA printer has a smaller build platform of 10” x 10” x 11” (250mm x 250mm x 280mm) and can bring out the smaller features and details. The beauty of this machine is it can build in normal resolution 0.004” (100 micron) layers or High Resolution with a finer laser beam diameter and finer layer slices of 0.002” (50 micron) to improve details, small features and accuracy.

SLA Materials

Here is a list of standard available materials:

  • Accura® Xtreme:
    • Grey ABS-like Material
    • Applications: Marketing Models, Form, Fit and Function Prototyping & Master Patterns for Urethane Molding, Vacuum Casting and Metal Castings
  • Accura® ABS White, SL 7810:
    • White ABS-like Material
    • Applications: Marketing Models, Design Check Prototypes & Master Patterns for Urethane Molding, Vacuum Castings and Metal Castings
  • Accura® SL 5530:
    • Amber, Rigid Material
    • Applications: Under the Hood Automotive Prototypes, Water & Fluid Resistance, & Electrical Component Prototypes
  • Accura® SL 7545:
    • Translucent Polypropylene-like Material
    • Applications: Snap-fits, Packaging Prototypes & Consumer Goods Prototypes
  • Accura ClearVue Free® SL 7870:
    • Clear, ABS-like Material
    • Applications: Clear Marketing Models, Point of Purchase Prototypes, Water & Fluid Resistance & Medical Modeling
  • Somos® Evolve 128:
    • White, ABS-like Material
    • Applications: Tough & Durable Prototypes, Functional Testing and Jigs & Fixtures

SLA Finishes Available (*Standard*)

  • Level 1 – Quick Finish = Support Removal Only
  • *Level 2 – Bead Blast Finish = Sand Support Areas & Sandblast*
  • Level 3 – Smooth Finish = Sand Part Smooth (Build Lines may be Visible)
  • Level 4 – Paint Ready Finish = Sand/Remove/Fill All Build Lines & Primer
  • Level 5 – Painted Finish = Sand/Remove/Fill All Build Lines, Primer and Paint/Mask/Texture as Needed (Show Quality Finish)
  • Mold Ready Finish for Master Patterns = Sand/Remove/Fill all Build Lines on Interior & Exterior, & Primer
  • Quick Cast Finish = Remove all Excess Resin from Interior Honeycomb
  • Quick Clear Finish = Support Removal & Clear Coat
  • Level 3 Clear = Wet Sand Parts Smooth & Clear Coat (Build lines and Small Defects may be Visible)
  • Supreme Clear = Wet Sand Parts Removing all Build Lines, Clear Coat & Buffing
  • Supreme Clear with Color Dye = Wet Sand Parts Removing all Build Lines, Clear Coat, Dye Color & Buffing
  • Metal Finish = Level 2 with Primer & Plated with Chrome, Nickel, Brushed Nickel, Gold or Other

Design Guideline:

  • Minimum Wall Thickness = 0.025”
  • Minimum Features Size = 0.025”
  • Tolerances = +/- 0.005” for first inch then +/- 0.002” per inch thereafter
  • Inserts = Install in Post-Processing with Adhesives
  • Holes = Build Holes & Threads into model for print and chase or ream in finishing


SLA 7870
Formlabs SLA machine
Painted Flower Pots
Painted SLA 7810
Plated SLA Material