SLA technology in practice

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SLA technology in practice

Stereolithography – what is it?

SLA 3D (stereolithography) is the oldest additive technology – the first scientific research work on additive manufacturing took place as early as the 1960s. However, the key date is considered to be 1986, when American Charles Hull received patent number 4,575,330 for a method called stereolithography. Thanks to this patent protection, Charles Hull founded his own company, 3D Systems, to manufacture and sell the first machines capable of 3D printing using SLA technology.

3D printing in SLA technology is a process involving polymerisation, i.e. the photo-curing of liquid resin using light of a specific wavelength. A working platform is immersed in the resin in a special cuvette of the device, to which the first layer of photopolymer adheres, which is the basis of the printed model. Once the first layer is cured, the working table is raised by a certain height, while a special scraper aligns the sheets to remove potential air bubbles. The layer is then cured with a laser beam, and the platform is then submerged again to the depth of the layer. The whole process is repeated until a finished model with the specified geometry is obtained.

Advantages of SLA printing

Stereolithography, despite being the oldest additive technology, has a number of important advantages that make it still widely used in prototyping and low-volume production. First and foremost, printed models stand out for being much more accurate than objects made using methods such as SLS or FDM. SLA technology also makes it possible to create very thin walls, and many types of photopolymers can be used for printing, which come in transparent and semi-transparent versions.

Application of SLA printing

The advantages listed above mean that SLA technology is still widely used for prototyping and low-volume production in many fields. It is most commonly used for conceptual models with visible internal structure, casting models, injection moulded parts, prosthetic designs, medical implant prototypes, structural components and semi-transparent models. The SLA method can be used wherever a cheaper and faster alternative to other manufacturing methods is required.

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SLA materials

A characteristic feature of stereolithography is the ability to print parts from a variety of photopolymers, i.e. special resins cured by polymerisation. The most commonly used SLA materials are:

  • flexible resin
  • casting resin
  • high-temperature resin
  • medical resin
  • ABS-like resin
  • PP-like resin

Each has its own characteristic properties and is used for specific purposes.