3D printing: What is SLA technology?

SLA is the abbreviation for “Stereolithography Appearance,”  which is the stereolithography molding method. Use a laser of a specific wavelength and intensity to focus on the surface of the light-curing material to solidify it sequentially from point to point and from line to surface to complete a layer of drawing work. Then the lifting table moves the height of one layer in the vertical direction and then solidifies. Another level. In this way, layers are superimposed to form a three-dimensional entity.
SLA is the earliest practical rapid prototyping technology, using liquid photosensitive resin raw materials. The process is to first design a three-dimensional solid model through CAD, use discrete programs to slice the model, and design the scanning path. The generated data will accurately control the movement of the laser scanner and the lifting platform; the laser beam is scanned through a CNC device. The device is irradiated to the surface of the liquid photosensitive resin according to the designed scanning path, so that a layer of resin in a specific area of the surface is solidified. When one layer is processed, a cross-section of the part is generated; then the lifting platform is lowered a certain distance, and the solidified layer is covered with another layer of liquid resin, and then the second layer is scanned. The second solidified layer is firmly bonded to the previous solidified layer, so that the three-dimensional workpiece prototype is formed layer by layer. After the prototype is removed from the resin, it is cured, polished, and then electroplated, painted, or colored to obtain the desired product.
SLA technology is mainly used to manufacture a variety of molds, models, etc.; it can also be used to replace the wax pattern in investment casting with an SLA prototype mold by adding other ingredients to the raw materials. SLA technology has faster molding speed and higher precision, but due to shrinkage during the curing process of the resin, stress or deformation will inevitably occur. Therefore, it is the trend to develop photosensitive materials with small shrinkage, fast curing, and high strength.
​Advantages of SLA technology:
1. The light-curing molding method is the earliest rapid prototyping manufacturing process. It is highly mature and has been tested over time.
2. Prototypes are made directly from CAD digital models, with fast processing speed and a short product production cycle, without the need for cutting tools and molds.
3. Can we process prototypes and molds with complex structural shapes or that are difficult to form using traditional means.
4. Make CAD digital models intuitive and reduce the cost of error repair.
5. Provide samples for experiments that can verify and check the results of computer simulation calculations.
6. It can be operated online and controlled remotely, which is conducive to the automation of production.
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Disadvantages of SLA technology:
1. The SLA system is expensive to build, and the use and maintenance costs are too high.
2. The SLA system is a precision equipment that operates on liquids and has strict requirements for the working environment.
3. Most of the molded parts are resin, with limited strength, stiffness, and heat resistance, which is not conducive to long-term storage.
4. The preprocessing software and driver software require a large number of calculations and are highly correlated with the processing effect.
5. The software system is complex to operate and difficult to get started; the file format used is not familiar to most designers.