Planet SLA

SLA is an industry accepted term for Stereolithography. Stereolithography is the time-proven process the Planet team used as its primary rapid prototyping and pattern making technology for the first 5 ½ years of operation. Plant Proto now uses PolyJet technology for its primary rapid prototyping and pattern making process. SLA parts continue to have many advantages.

How it works

Stereolithography is an additive fabrication process that is accurate to about 0.006”. The process builds parts one layer at a time in a vat of UV-curable liquid resin. On each layer, a laser beam traces a cross-section of the part being built on the surface of the liquid resin. As UV laser light cures the pattern traced on the resin, the newly solidified resin adheres to the layer below. A platen within the vat of UV curable liquid lowers 0.002” to 0.006” (0.05 mm to 0.15 mm) as each layer of resin is cured. A part is accurately built over time.

At the completion of the building process, parts are cleaned of excess resin by immersion in a chemical bath and post-cured in a UV oven.

Stereolithography requires the use of build software generated support structures to attach the part to the elevator platform and to prevent geometry deflecting due to gravity. Supports must be removed from the finished part manually. A fresh-off-the-machine part made by a SLA process has small tips or points spread across the surface of the part. These small points are the remaining roots of the support structure. These tips or points need to be hand-sanded from every SLA part made. All SLA parts are normally sanded. Continuing improvements in SLA build machines and software minimize the effect of build structure on the parts as built.

Advantages

Specialized SLA machines can build large, single-piece parts up to 60” in length with the material performance attributes and accuracy of smaller machines. Custom machines can build larger parts. Most SLA machines can produce parts with a maximum size of 20” x 20” x 24”. Specialized machines can build even larger parts. Large parts may require several days to build a single part. Prototypes made by SLA are usually strong enough to be machined and can be used as master patterns for resin castings and various metal casting processes. Planet Proto generally recommends the Planet SLA process for parts that are larger than 15” x 18” or have a depth of more than 3 inches. If you don’t know which build process is best for your application, please call Planet Proto and ask a representative about build options and their advantages.