Stereolithography (SLA) is a form of 3D printing technology used for creating models, prototypes, patterns, and production parts in various industries including automotive, aerospace, jewelry, dental, and medical. It was invented by Charles W. Hull in 1984, who also founded 3D Systems, one of the first companies to commercialize this technology. Here is a detailed overview:
Technology
Stereolithography works on the principle of photopolymerization, where a liquid polymer resin is exposed to a UV laser or light source to cure or harden. Here's how the process works:
- The build platform starts at the top of the resin vat, and the UV laser traces the first layer of the object on the surface of the liquid resin.
- Where the laser touches the resin, it solidifies or "cures," creating a thin layer of the object.
- The platform then lowers by a distance equal to the thickness of one layer, and another layer is traced over the previously cured layer.
- This process repeats, building the object layer by layer from bottom to top.
- After printing, the object is removed from the vat, and often post-processing like washing in solvent, curing in a UV oven, or sanding might be necessary to achieve the desired finish.
Materials
The primary material used in stereolithography is photopolymer resin. These resins can vary in:
- Mechanical properties: from flexible to rigid.
- Optical clarity: clear, opaque, or colored.
- Biocompatibility: for medical applications.
- Heat resistance and durability.
Applications
SLA technology is particularly valued for:
- Prototyping: Creating high-resolution, smooth surface parts for design verification.
- Jewelry: Producing master patterns for investment casting.
- Dental: Fabricating dental aligners, crowns, bridges, and models.
- Hearing Aids: Custom shells for hearing devices.
- Art and Design: Creating intricate sculptures or architectural models.
Advantages
- High resolution and fine feature details.
- Smooth surface finish which can reduce post-processing needs.
- Wide range of materials with specific properties.
- Capability to produce complex geometries and thin walls.
Limitations
- Requires support structures for overhanging features, which can be challenging to remove.
- Post-curing is often necessary to achieve full mechanical properties.
- Material costs can be high compared to other 3D printing technologies.
- The size of objects is limited by the dimensions of the resin vat.
History
After Charles W. Hull's initial invention, stereolithography technology saw rapid development:
- In 1986, Hull patented the process, and the first commercial SLA machine was introduced by 3D Systems.
- The 1990s saw improvements in speed, accuracy, and materials, making SLA more accessible for various applications.
- By the 2000s, the technology had matured with significant advancements in software control, automation, and resin formulations.
External Links
Related Topics