The Difference Between Rapid Prototyping Material PLA and SLA Resin

PLA, the short name for polylactic acid polymer, is a material extracted from corn starch that is environment-friendly and degradable. It melts when heated to a particular temperature and re-solidifys when temperature decreases. The rule of 3D printing of PLA is based on the melting and forming characteristics at different temperatures.

The photosensitive resin is a liquid composed of polymer monomers and prepolymers with a photoinitiator. The ultraviolet-light irradiation with a precise wavelength causes the polymerization reaction to complete the curing.

The Difference Between PLA and SLA UV Resin

In the Forming Process

PLA uses FDM (Fused Deposition Manufacturing) technology for forming processing. The working rule is to feed the linear material into the extrusion molding machine through the feeding system. The linear gets heated and melted on the machine head and extruded from the extrusion head through a particular pressure. At the same time, the computer controls the extrusion head to walk out of the track on the lathe to form the model layer by layer.

The photosensitive resin molding process is called SLA, and the full name is light-curing three-dimensional modeling technology. The process is to immerse the photosensitive resin liquid on the worktable and then irradiate the liquid surface with ultraviolet light for model curing and forming. After forming one layer, the worktable will lower the height so that liquid immerses the worktable again for the next layer until the model is finished.

Those are the differences between PLA and SLA printing. PLA printing is completed by mechanical movement, while SLA photosensitive resin is done by light.

Requirement

The SLA photosensitive resin technology involves more optics and material science, which has a high threshold and few device manufacturers but the power of the large companies. The cost for one machine is from hundreds of thousands to millions. The PLA FDM technology, more about machine control and movement, has a low requirement on technology, leading to many devices from different manufacturers of various quality. Compared with SLA, it costs less to purchase types of equipment and consumables but has lower printing stability and quality. The SLA processing is generally for enterprises’ markets, and the PLA is usually for personal or educational use.

Efficiency

The PLA printing extrudes the melt-linear and forms the model. The hole for extruding is 0.2 to 0.5mm in diameter. Usually, it spent 72 hours continuously working on a model in 1kg with PLA printing. If something goes wrong during the processing, you have to restart the project again from the beginning. With SLA printing, a machine can achieve an output of several kilograms a day.

Quality

Both PLA and SLA printing are layer-by-layer molding methods. The fused deposition modeling has a flaw in the dangling part of the model. In SLA printing, the dangling parts have better support by the liquid, so the model will not have obvious flaws in the dangling parts. In addition, each layer of the fused deposition has 0.2mm or more in height, causing the PLA to have a clear step pattern in the model. The thickness of each layer of SLA is only 0.1 or 0.05mm, which is more precise on the surface. In short, PLA has a rough surface, and SLA is smooth and in high precision on the surface.

Price

Because of the low price of equipment and consumables, in general, the PLA 3D printing models are relatively cheap. We can adjust the filling density of the model during the process and reduce the consumables quantities in use for large-size models. For a large model with a low requirement on the surface, PLA printing is a priority selection to reduce the cost.

Material

FDM melts the original consumables and accumulates them. Therefore, many consumables are available in use. They are PLA, ABS, TPU, PETG, and similar materials in different colors. PLA printing can directly print all types of models in various colors. However, the SLA photosensitive resin printing is limited to milky white, light red, gray transparent, etc.