What is the difference between SLA and SLS rapid prototyping?

SLA(Stereo lithography Apparatus) process, also known as photo-modeling, stereo lithography and stereo printing, is characterized in that liquid photosensitive resin is filled in a liquid tank, the laser beam is controlled by a computer to track the track of layered cross section, and the liquid resin in the tank is irradiated to solidify this layer, then the lifting table descends one layer, and another layer of resin is covered on the molding layer, and then a new layer is scanned, and the newly solidified layer is firmly bonded with the previous layer. The process is characterized by high precision of prototype parts, good strength and hardness of parts, and can manufacture hollow parts with particularly complicated shapes. The model is flexible and can be disassembled at will, which is an ideal method for indirect modeling. The disadvantage is that it needs support, the shrinkage of resin will lead to the decline of precision, and the light-cured resin has certain toxicity, which does not conform to the development trend of green manufacturing.

In SLS (Selective Laser Sintering) process, powders of metals, ceramics, ABS plastics and other materials are often used as forming materials. The process flow is as follows: firstly, spread a layer of powder on the workbench, and then selectively sinter it with a laser beam under the control of a computer (the hollow part of the part is still made of powder material without sintering), and the sintered parts are solidified together to form a solid part of the part. After one layer is completed, proceed to the next layer, and the new layer is sintered firmly with the previous layer. After all sintering is completed, excess powder is removed to obtain sintered parts. The process is characterized by a wide range of materials, which can not only make plastic parts, but also make parts made of ceramics, metals, waxes and other materials. The modeling accuracy is high and the prototype strength is high, which can be used for functional testing or assembly simulation.