How Does SLA Work?

Based on the principle of photopolymerization of liquid photosensitive resin. Under the irradiation of ultraviolet light with a certain wavelength (325 or 355 mm) and intensity (w = 10-400 MW), the liquid material can rapidly undergo photopolymerization reaction, and the molecular weight of the material increases rapidly, and the material changes from liquid to solid.

At the beginning of SLA machine forming, the working platform is under the liquid surface, and the focused laser spot is scanned point by point on the liquid surface according to the instructions of the computer, and solidified point by point on the inner side of the same layer. When a layer of scanning is completed, the irradiated area is solidified, and the non irradiated area is still liquid resin. Then, the lifting frame drives the platform down one more layer of height, which is covered with a layer of resin for the second layer scanning. The newly solidified layer is firmly adhered to the previous layer, and this is repeated until the 3D parts are made.

Newly built parts needs to be taken out of machine, in order to clean additional resins , and some surfaces need to be polished by hand. Sometimes, objects need to be put into ultraviolet light for further curing according to printing requirements.

The Disadvantages Of SLA

• The cost of SLA machine is high, and the cost of use and maintenance is too high. SLA system is a kind of precision equipment to operate liquid, which has strict requirements for working environment.
• Most of the molded parts are made of resin, which is not conducive to long-term preservation due to high price, limited strength, stiffness and heat resistance.
• This kind of molding product has high requirements for storage environment. If the temperature is too high, it will melt and the working temperature should not exceed 100 ℃. After curing, the photosensitive resin is brittle, easy to break and has poor processability. The molded parts are easy to absorb moisture and expand, and the anti-corrosion ability is not strong.
• Photosensitive resin pollutes the environment and makes human skin allergic.
• It is necessary to design the support structure of the workpiece, so as to ensure that every structural part can be reliably positioned in the molding process. The support structure needs to be removed manually when it is not fully cured, which is easy to damage the molding parts.