SLA Printers build accurate parts directly from 3D CAD data without tooling by converting liquid materials and composites into solid cross-sections, layer by layer, using an ultraviolet laser. The bed then lowers, the part is coated with a new layer of resin, and the next layer is built on top of the others until the part is finished. When a part is complete, it is cleaned in a solvent solution to remove wet resin remaining on the part surface. Afterward, the part is put in a UV oven to complete the curing process. SLA Printers offer high throughput, unmatched part resolution and accuracy, and a wide range of print materials. No process addresses a wider range of applications, including the most demanding rapid manufacturing applications.
When Charles ‘Chuck’ Hull, the founder of 3D Systems, invented Stereolithography, SLA, in 1986, he launched a revolution in product development across every marketplace from transportation, recreation and healthcare to consumer goods and education.
SLA is all about precision and accuracy, so it is often used where form, fit and assembly are critical. The tolerances on an SLA part are typically less than .05mm, and it offers the smoothest surface finish of any additive manufacturing process. Considering the level of quality SLA can achieve, it’s particularly useful for creating highly precise casting patterns (e.g., for injection molding, casting and vacuum casting) as well as functional prototypes, presentation models, and for performing form and fit testing. SLA technology is extremely versatile and it can be used in any number of areas that require precision above all else.
Keep in mind that, unlike with SLS, SLA parts do utilize support structures, and they require a bit more post-processing. But the post-processing options are also some of SLAs greatest advantages. Models can be vapor honed, or bead or sand blasted. SLA parts can even be electroplated with metal, such as nickel. Electroplating not only makes the part significantly stronger, but it also makes the part electrically conductive and more dimensionally stable in moist environments.
In terms of benefits, SLA allows us to save time on highly precise parts, especially when you require a number of functional prototypes or a quick single casting pattern. SLA brings us painstaking accuracy without the painstaking time. Because of SLA’s speed and precision, prototypes are easy to make and faithful to the final design, which means we can identify design flaws, collisions and potential mass-manufacturing hurdles before production begins. For low to mid-volume parts normally machined from polypropylene or ABS, SLA provides comparable characteristics and doesn’t require slow, expensive retooling for customization or in the event a tooling change is required. In addition, SLA allows for lower material costs, as the unused resin stays in the vat for future projects. SLA materials are wide ranging in mechanical properties and offer wide application opportunities for parts requiring ABS or polypropylene-like characteristics such as snap-fit assemblies, automotive styling components and master patterns.
SLA materials are available for higher-temperature applications and clear materials are available with polycarbonate-like properties. Biocompatible materials are available for a wide range of medical applications such as surgical tools, dental appliances and hearing aids. Other materials are specifically formulated for patterns, offering low ash creation and high accuracy while also being expendable.