The SLS process uses a laser to selectively sinter the solid powder layer by layer, layer by layer to obtain the required parts. Compared with SLA technology, SLS process uses infrared laser beam (such as CO2 laser), and the material is changed from liquid photosensitive resin to powder of plastic, wax, ceramic, metal and their composites. SLS and DMLS (Direct Metal Laser Sintering) technology are essentially the same, but the latter is generally aimed at the processing of metal alloys.
First, the principle of SLS process
1. The powder particles are stored in the feeding bin on the left. The lifting platform of the powder feeding bin rises upward during printing, and the powder higher than the printing plane is pushed onto the printing plate of the printing bin through the spreading roller to form a very thin layer. And a flat powder layer;
2. At this time, the laser beam scanning system will selectively scan the powder layer according to the two-dimensional CAD path of the slice. The scanned powder particles will be sintered together due to the high temperature of the laser focus, and a solid body with a certain thickness will be generated Thin slices, the unscanned area still remains the original loose powder;
3. After the sintering of a layer is completed, the printing platform is lowered according to the height of the slice, and the horizontal roller flattens the powder again, and then starts the sintering of a new layer. At this time, the layers are sintered together at the same time; 4) Repeat so, Until all layers are sintered. Remove and recycle the unsintered powder, then you can take out the printed solid model
Second. Advantages of SLS process
1. Molding materials are very wide. In theory, any powder material that can form interatomic bonds after heating can be used as a molding material for SLS;
2Can print any complex structure, including hollow structure, hollow structure, etc. The process has nothing to do with the complexity of the parts, and the strength of the parts is high;
3. The material utilization rate is high, the unsintered powder can be reused, and the material waste is less;
4. No supporting structure is needed, and the loose powder plays a supporting role, reducing the difficulty of model processing in the early stage of printing;
5. The SLS process can process standard plastics with good mechanical properties;
6. The types of machinable materials continue to increase, and the price advantage is obvious in small batch production.
SLS process can be applied in almost all walks of life, not only for the proof of concept in the R&D and design stage, but also for the production of functional prototypes, the production of terminal parts, and the direct or indirect use of various rapid casting. At present, the process is widely used in aerospace, home electronics, automobile manufacturing, medical aids, arts and crafts, and lighting.
Three, SLS process application range
1. Process the appearance, assembly and functional prototypes of standard plastics.
2. Supporting parts, such as clamps, fixing devices, etc.
3. Small batch production.