Stereolithography (SL)

image of Explanation of the technology stereolithography including characteristics, materials, machines, vendors, applications and process chain. image of Explanation of the technology stereolithography including characteristics, materials, machines, vendors, applications and process chain.



Process description

A UV laser is curing a liquid photopolymer in a vat. The part is built by lowering the build platform into the vat. Read more

Stereolithography machines build parts out of liquid photopolymer through polymerization activated by a UV laser. Parts are built on to a build platform inside a vat filled with the liquid photopolymer. The laser is scanning the surface of the vat which is solidifying. The build platform is lowered subsequently into the vat and the part is built layer by layer.

Stereolithography requires support structures for overhangs, which are built in the same material.

Advantages / disadvantages

Stereolithography can build large parts with very good accuracy and surface finish. A wide range of material allow to build parts with specific characteristics. However, stereolithography only works with photopolymers which are not stable over time and have not well defined mechanical properties. Read more

The technology can achieve very good accuracy, surface finishes and details. Machines with large build volume enable large parts. Further, there is a wide range of photopolymer materials available which can build parts with different characteristics (e.g. certain materials can mirror the characteristics of engineering plastics over a short period of time)

Stereolithography only works with photopolymer materials. Mechanical properties of parts are therefore not durable over time. Further, materials are expensive and the build process is slow.

Application areas

  • Prototypes are built with fine details, very good accuracy and surface finishes for visual, form / fit and sometimes functional testing. Materials have been specifically developed to mirror the mechanic properties of engineering materials (in the short term), e.g. high heat resistance.
  • Casting patterns are produced with stereolithography as very good accuracy and surface finishes are achieved.

Characteristics / restrictions

  • Maximal build envelope: 2’100 x 700 x 800 mm3
  • Minimum feature size: 0.1 mm
  • Typical tolerance: +/-0.15 mm
  • Minimum layer thickness: 0.016 mm

Characteristics are only indicative, as there are different types of machines available.

Process chain

Stereolithography parts are often post cured in an UV oven and support structures are mechanically removed. Read more

Pre-build planning

The production of parts is planned in a build preparation software. One or several parts are loaded from digital 3D files (typically in the STL file format). These can be arranged to fill the entire volume of the build envelope as long as they are anchored to the build platform.


  • Removal of part from vat: Parts are elevated from the vat and drained
  • Post curing: Certain parts are post cured in a UV oven to achieve complete polymerisation.
  • Removal of support structures: Support structures are mechanically removed.
  • Surface finish: Parts can be processed to improve surface finish –by removing material (e.g. polishing, grinding, peening) or by adding material (e.g. painting, coating)

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