After years of technological development, 3D printers are no longer superior, and have penetrated into the daily lives of ordinary people. There are more and more technologies that can be used in 3D printing, and the application fields that can be printed have become wider and wider. Light-curing 3D printer technology has also emerged. The light-curing technologies commonly used in the public mainly include DLP, SLA and LCD.
First of all, let me talk about what light-curing 3D printing technology is. Its principle is to print items in a layer-by-layer printing method. As for the printing material used, it is different from the roll of FDM 3D printer. The printing material used in the light-curing 3D Printer is liquid photosensitive resin. This photosensitive resin will chemically cure when exposed to light. The light-curing 3D printer prints a physical model by shooting light onto the liquid photosensitive resin. In terms of accuracy, the objects printed by light curing technology are finer than those printed by FDM or other printing technologies, and are suitable for making fine models, such as dentistry and jewelry, fine parts, and so on.
The following mainly introduces two mainstream light-curing technologies: light-curing DLP 3D printing technology and light-curing SLA printing technology. The main difference between these two 3D printing technologies is the way they shoot light onto the photosensitive resin of the printing material.
DLP (Direct Light Processing) light-curing 3D Printer has a built-in light projector. DLP printers use a projector to project light onto the photosensitive resin of the printing material to cure the resin. Due to the stacked printing, the 3D model is first cut horizontally by the 3D printing software into layers, and then the DLP projector is used to project the shape pattern light of the first layer of 3D model onto the liquid photosensitive resin one by one. The photosensitive resin is cured and formed by light. After the first layer is printed, the printing platform will rise, so the printed object will also rise at the same time. Then the projector will project the shape and pattern of the next layer of 3D model onto the photosensitive resin. Repeated cascading printing finally prints the object into shape. It is worth mentioning that the printed objects are printed upside down during printing, which is different from FDM printing technology. Because DLP uses a projection screen to illuminate a single image of each layer on the printing platform, the image of each layer is formed by small squares called pixels.
As for the SLA (Stereolithography) 3D printing technology, instead of using a light projector, it uses a laser to shoot the laser onto the liquid photosensitive resin, which cures the photosensitive resin layer by layer, and finally obtains the shape of the entire object. When SLA light-curing 3D printer emits laser light, it will not be able to shoot out the pattern of a whole layer of 3D model like DLP machine. The laser is shot point by point on the liquid resin to form a cured layer. The main components of SLA light-curing printers are similar to DLP printers, including a liftable printing platform. After the first layer of photosensitive resin is solidified, the platform will rise a certain distance, and then use laser to print the second layer, and so on. Print layer by layer, and finally print into a whole shape. There is also a container containing liquid photosensitive resin. In addition, SLA uses two motors, one on the X axis and the other on the Y axis. The motor will aim the laser to the specified printing coordinates to cure the resin in that place. Through the 3D slicing software, the 3D model will be analyzed into a series of points and lines with different coordinates, and the SLA machine will accurately hit the laser on the liquid resin of the printing material according to the coordinate path. Since SLA and DLP light-curing 3D printers have different light projection methods, the time required for SLA printing will be longer, especially when printing large objects, the printing time used by DLP light-curing 3D printers will be much shorter. But in terms of the relative printable area, because DLP uses projection, the relatively printable area is thinner, while SLA is not affected by projection, so the printable area is not limited.
The following figure shows the difference between SLA and DLP printing: