1, fused deposition molding (FDM)
FDM is probably the most widely used process at present, and it is adopted by many consumer 3D printers because it is relatively easy to realize:
FDM heating head heats hot-melt materials (ABS resin, nylon, wax, etc.). ) to the critical state, making them semi-fluid, then the heating head will move along the two-dimensional geometric trajectory determined by CAD under the control of software, and at the same time, the nozzle will extrude the semi-fluid material, and the material will instantly solidify to form a thin layer with contour shape.
This process is very similar to the printing process of a two-dimensional printer, except that instead of ink, the print head produces a melt of ABS resin and other materials. At the same time, due to 3D
The print head or base of a printer can move vertically, so materials can be quickly stacked layer by layer, and each layer is CAD.
The trajectory determined by the model prints a certain shape, so the designed three-dimensional object can be printed finally.
2. Stereolithography
According to Wikipedia, the first rapid prototyping equipment in 1984 adopted light-curing rapid prototyping technology. In rapid prototyping equipment, SLA is the most deeply studied and widely used. At ordinary times, we usually refer to this process as "light curing", and the basis of this process is photosensitive resin which can produce polymerization reaction under ultraviolet radiation.
Like other 3D printing processes, SLA curing equipment will slice the 3D digital model of the object before starting to "print" the object. Then, under the control of the computer, the ultraviolet laser will scan the liquid resin point by point along the cross-sectional outline of each layer of the part. The scanned resin thin layer will produce polymerization reaction, gradually form lines from points, and finally form the cured cross section of the thin layer of parts, while the resin that has not been scanned will remain in the original liquid state.
When one layer is cured, the lifting table moves a distance of one layer thickness, and a new layer of liquid resin is covered on the surface of the cured resin of the previous layer, and scanning curing is carried out again. The newly solidified layer is firmly combined with the previous layer, and so on until the prototype of the whole part is manufactured.
SLA technology is characterized by high precision and good surface quality, and can manufacture parts with particularly complicated shapes (such as hollow parts) and parts with particularly fine shapes (such as handicrafts and jewelry).
3. Selective laser sintering
Layered cutting and layer-by-layer manufacturing of digital models are the basis of 3D printing technology, so I won't go into details here. In addition, SLS process and SLA.
The light curing process is similar, that is, all substances need to be cured into a whole by laser. The difference is that SLS
In this process, infrared laser beam is used, and the material changes from photosensitive resin to powder of plastic, wax, ceramic, metal or their compound.
First, a thin layer of raw material powder (sub-millimeter level) is not spread on the workbench, and then the laser beam under computer control passes through the scanner at a certain speed and energy density, and is scanned according to the two-dimensional data of different layers. The powder scanned by laser is sintered into a solid sheet with a certain thickness, and the unscanned part is still loose powder.
After scanning the first layer, the next layer will be scanned. Firstly, according to the thickness of the cross section of the object, the workbench is lifted, and the powder is smoothed again by the powder spreading roller, and then a new layer is scanned. This process is repeated until all layers are scanned. Remove excess powder, and then after proper post-treatment, such as grinding and drying, the parts can be obtained.
At present, when this process is applied, wax powder and plastic powder are used as raw materials, but the process of bonding or sintering with metal powder or ceramic powder has not been actually applied.
4. Layered Object Manufacturing (LOM)
In the laminating process, the machine will heat the foil coated with hot sol on one side through a hot roller, and the hot sol will be sticky after heating, so that the materials composed of paper, ceramic foil and metal foil will stick together. Then, according to the layered data of the CAD model, the upper laser uses the laser beam to cut the foil into the inner and outer contours of the manufactured parts. Then a new layer of foil is laid, bonded with the lower cutting layer by hot pressing device, and then cut by laser beam. Then repeat this process until the whole part is printed.
It is not difficult to find that LOM process still has the shadow of traditional cutting. However, it does not use large pieces of raw materials for overall cutting, but divides the original part model into multiple layers and then cuts them layer by layer.
5.3D printing (3DP)
Stereoscopic printing is also called stereoscopic printing. Wikipedia shows that 1989, Emmanuel M. Sachs and John S. of MIT.
Hagarty and others applied for the patent of 3D printing technology in the United States, followed by Emmanuel M. Sachs and John S ..
Hagarty perfected the technology many times, and finally formed today's 3D printing technology.
From the working mode, 3D printing is closest to the traditional 2D inkjet printing. Like SLS process, 3DP also makes parts by bonding powder into a whole. The difference is that it is not bonded by laser melting, but by adhesive sprayed from nozzle.
Under the control of the computer, the nozzle runs according to the two-dimensional data of the model section, and selectively sprays adhesive at the corresponding position, finally forming a layer. After each layer is bonded, the forming cylinder descends by a distance equal to the thickness of the layer, and the powder supply cylinder rises by a certain height to push out the excess powder, which is pushed to the forming cylinder by the powder spreading roller, leveled and compacted. Repeat this cycle until the whole object is bonded.