Stereolithography (SLA)

Stereolitography is an additive manufacturing technology, by which we obtain epoxy resin parts with a good dimensional tolerance, usually with acceptable mechanical properties. Stereolithography is the most appropriate technology to manufacture the master piece used to create silicone moulds or prototypes that verify the geometry and visual appearance of the product.

What is the stereolithography?

Stereolithography is an additive manufacturing technology (3D printing) for prototyping, models or final products, combining layers of epoxy resin polymerized by an ultraviolet laser of low power.

How stereolithography works?

Once 3D geometry to be manufactured has been drawn, the manufacturing position is decided and sectioned into horizontal layers of approximately 0.1mm (depending on the required accuracy). A computer program organizes and translates information from a file in .stl format generating information of each layer. The .stl file is the interface used to translate the 3D CAD files.

A UV laser draws and cure these layers on the surface of the liquid epoxy resin in a vat; each layer is glued to the previous by the effect of the laser; at the same time brackets are made to fix the piece to a shaped base fence that keeps going down and positioned on each layer; these brackets ensure that the manufactured part does not fall or deformed.

Once the piece has benn manufactured it goes through a cleansing process, removing brackets and post-cured in an oven of ultraviolet light to be completely solidified.

Stereolithography applications

Parts made of stereolithography can be used as master or pattern, for creating silicone molds, functional models or final parts for design validation. It is a technology well regarded for its greater precision and better surface finishing.

Advantages of stereolithography

Some advantages of stereolithography are:

  • Rapid and complex prototyping manufacturing
  • Excellent reproduction of details and precision parts
  • High speed
  • Good surface finishing
  • Parts of pieces separately built can be pasted
  • Very thin sides can be created
  • Allows different surface finishes and painted
  • Different materials manufacturing: transparent, flexible, translucent

Disadvantages of stereolithography

Some disadvantages of stereolithography:

  • Fragility (depending on the resin used)
  • The need to use supports for stabilizing protruding surfaces during the manufacture process of the parts
  • Not very demanding mechanical and thermal tests
  • Not recommended to nest on other pieces during manufacture
  • Material sensitive to humidity and temperature
  • High cost of maintenance
  • First resin setup cost

Fields of application for stereolithography

Technical offices, departments of R & D, design centers in different industries, architecture, medicine, which require:

  • Master piece to manufacture silicone molds
  • Functional Prototypes
  • Models for presentation
  • Parts that will require an easy surface finish
  • Pieces of high dimensional quality

Stereolithography technical data

  • Solid state laser Nd:YVO4
  • Wavelength: 354.7nm
  • Beam diameter: 0.2 – 0.3mm
  • Drawing speed: 5m/sec (depending on the laser power)
  • Layer thickness: 0.05-0.15mm, (usually 0.1mm)
  • Resolution X/Y: 0.0177mm