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How To Work The SLA
Apr 14, 2018

HOW DOES IT WORK?

There are several industrially applied systems using SL techniques. The most representative system is the SLA from 3D Systems (Valencia, California, USA). It consists of four main components: the slice computer, the control computer, the process chamber and the laser unit. The slice computer reads the triangulated CAD model and cuts it into thin slices according to process parameters. The input for the slice computer is usually a file generated on a CAD workstation (.STL file). Afterwards, the control computer reads the file (.SLI) provided by the slice computer and allows moving and rotating the parts of the machine (elevator, sweeper, mirrors, etc.) during the manufacturing time. The process chamber is the „heart" of the system: initially, the elevator is located at a distance from the surface of the liquid equal to the thickness of the first layer. The laser beam will then scan the surface following the contours of the slice. The liquid is a photopolymeric fluid which, when exposed to the UV laser beam, solidifies by low energy absorption. When the laser beam has completely „written" the first layer, the elevator is moved downwards and the following layers are produced like the first. Finally, the part is removed from the vat and completely cured in a special UV post cure apparatus. Because the part is built in a liquid environment and the interior of the part contains liquid, it is necessary to add support structures. They are used to hold the parts in place while the layers are being built and to maintain the structural integrity of the part. The support structures attach the part to the elevator platform (a perforated steel plate) and have to be removed when the part is completely manufactured.