What Vat Photopolymerization isVat photopolymerization, also known as stereolithography (SLA), is the process by which a liquid is cured by a light source, turning it into a solid . This phenomenon became known as polymerization and was the very first industrial additive manufacturing technology . A laser draws the shape of each layer into a resin-filled vat, and once it solidifies, the build platform moves to make room for the next layers. During this process, fresh resin fills the gaps.
- The build platform lowers down into the resin vat by the layer thickness.
- UV light is used to cure the resin layer by layer. The platform moves downwards as additional layers are built on top of the existing layers.
- In some machines, a blade moves between layers to provide a smooth resin base to build the next layer on.
- The model is removed after the vat is drained of resin.
Once the model is complete, it cures in a special chamber with additional UV light . When the resin is fully cured, the model is ready for use.
This process uses plastics and polymers, and the polymers must be UV-curable.
Equipment Used Today
Vat photopolymerization is used in several markets because the materials are easily accessible . The method is useful for making various consumer products, like hearing aids. The manufacturer Sonova uses SLA in the production of hearing aids to create products customized to individual clients . Another industry is the shoe industry; Adidas and Nike use this technology for serial production .
Pros and Cons
- High level of accuracy 
- Smooth finishes 
- Faster printing time
- While many additive manufacturing processes need to trace the part pattern on each layer, Vat Polymerization can print by projecting the entire layer pattern on the liquid surface 
- Models might be used more for quick displays or views of a newly modeled part 
- Support structures often required 
- Lengthy post-processing 
- Models are still not as good in terms of impact strength and lasting durability, especially when compared to injection molded parts 
Video Demonstration of the Vat Photopolymerization Process