3D printing is a 3 d model that is modeled by computer modeling software and then built? Partition? Slice layer by layer, that is, slice, thus guiding the printer to print layer by layer. By reading the cross-section information in the document, the printer prints these cross-sections layer by layer with liquid, powder or sheet material, and then bonds the cross-sections of each layer together in various ways to form an entity. The characteristic of this technology is that almost any shape can be made. The resolution of the cross-sectional thickness (that is, the Z direction) and the plane direction (that is, the X-Y direction) printed by the printer is calculated in dpi (pixels per inch) or microns. The general thickness is 100 micron, that is, 0.1mm. Print? Ink drops? The diameter of is usually 50 to 100 micron. According to the size and complexity of the model, it usually takes several hours to several days to make a model by traditional methods. The technology of 3D printing can shorten the time to several hours, which of course depends on the performance of the printer and the size and complexity of the model. Traditional manufacturing technologies such as injection molding can produce a large number of polymer products at a lower cost, while three-dimensional printing technology can produce a relatively small number of products in a faster, more flexible and lower cost way. A desktop-sized three-dimensional printer can meet the needs of designers or concept development teams to make models.

General technology

At present, the rapid prototyping technologies on the market are divided into 3DP technology, FDM melt lamination technology, SLA stereo lithography technology, SLS selective laser sintering technology, DLP laser molding technology and UV ultraviolet molding technology. Among them, the 3D printer using FDM melt lamination technology has the lowest cost. Most 3D printers for ordinary consumers use this technology.

1.3DP technology:

3D printers using 3DP technology use standard inkjet printing technology. By laying the liquid connector on the powder thin layer, the components are created layer by layer by printing the cross-sectional data, and a three-dimensional solid model is created. The sample model printed by this technology is consistent with the actual product color, and the color analysis results can be directly described on the model, conveying more information. The working principle of 3DP technology is as follows: firstly, spread a layer of powder, then spray the adhesive on the area to be molded with a nozzle, so that the material powder can be bonded to form a part cross section, and then repeat the process of spreading powder, spraying and bonding, and stack layer by layer to get the final printed part.

The advantage of 3DP technology lies in its high molding speed, no need of supporting structure, and the ability to output color printed products, which is difficult to achieve by other technologies. The typical equipment of 3DP technology is zprinter series of zcorp under 3DS, which is also used in 3D photo studios. The products printed by zprinter's z650 can output up to 390,000 colors, which are very rich. The printed products are closest to the finished products of 3D printing technology in color appearance.

However, 3DP technology also has some disadvantages. First of all, the direct finished product bonded by powder has low strength and can only be used as a test prototype. Secondly, due to the working principle of powder bonding, the surface of the finished product is not as smooth as SLA, and the fineness is also inferior. Therefore, in order to produce products with sufficient strength, a series of subsequent processing procedures are needed. In addition, due to the complexity and high cost of manufacturing related materials powder, 3DP technology is mainly used in professional fields, and only one PWDR project is started at the desktop level, but it is still in the state of 0. 1, and the subsequent progress remains to be seen.

2.FDM melt lamination molding technology;

FDM melt lamination molding technology is to heat and melt filamentary hot-melt materials, and at the same time, under the control of computer, three-dimensional nozzles selectively coat the materials on the workbench according to the cross-section profile information, and then quickly cool to form a layer of cross-section. After one layer is formed, the machine workbench is lowered by one height (that is, the layered thickness) and then the next layer is formed until the whole three-dimensional formation. There are many kinds of molding materials, high strength and high precision, which are mainly suitable for molding small plastic parts.

The advantages of FDM technology are simple manufacture and low cost. However, the desktop FDM printer is difficult to accurately control the discharging form and molding effect because of its simple discharging structure, and the temperature has a great influence on FDM molding effect. However, desktop FDM 3D printers usually lack constant temperature equipment, so the finished product accuracy of desktop 3D printers based on FDM is usually 0.3 mm-0.2 mm. A few high-end models can support the layer thickness of 0. 1mm, but it is greatly affected by temperature. In addition, most FDM products are produced by layered deposition on their edges. Step effect? It is difficult to achieve the 3D printing effect of what you see is what you get, so FDM is rarely used in the field of high-precision rapid prototyping.

3.SLA stereo lithography technology;

SLA photo-curing rapid prototyping technology uses photosensitive resin as raw material, controls laser by computer, and scans the surface of liquid photosensitive resin point by point according to the cross-sectional information of each layer of the part. The resin thin layer in the scanning area is cured by photopolymerization to form a thin layer of the component. After one layer of curing is completed, the workbench moves down by one layer of thickness, and then a new layer of liquid resin is coated on the surface of the previously cured resin until a three-dimensional solid model is obtained. This method has the advantages of fast forming speed, high degree of automation, arbitrary complex shape and high dimensional accuracy, and is mainly used for rapid forming of complex and high-precision fine workpieces.

4. Selective laser sintering technology;

SLA photo-curing rapid prototyping technology is to spread a layer of powder material (metal powder or nonmetal powder) on the workbench in advance, and then under the control of the computer, let the laser sinter the solid powder according to the interface contour information, and then continuously circulate and pile up layer by layer. The method is simple in manufacturing process, wide in material selection range, low in cost and fast in molding speed, and is mainly used for directly manufacturing rapid molds in the foundry industry. Although laser sintering technology has obvious advantages, it also has defects. Firstly, the sintered surface of powder is rough and needs post-treatment. Secondly, a high-power laser is used. Besides the equipment cost, many auxiliary protection processes are needed. The overall technical difficulty is high, and the manufacturing and maintenance costs are too high for ordinary users to bear. Therefore, the application scope is mainly concentrated in the high-end manufacturing field, and there is no news about the research and development of desktop SL3D printers. It may take some time to enter the ordinary civilian field.

5.LOM layered entity manufacturing method:

LOM layered solid manufacturing method takes sheets (such as paper, plastic film or composite materials) as raw materials, and the laser cutting system cuts the paper coated with hot melt adhesive on the back into the inner and outer contours of the workpiece according to the cross-sectional contour data extracted by the computer. After cutting one layer, a new layer of paper is superimposed by the feeding mechanism, and the cut layers are bonded together by the hot pressing device, and then cutting is carried out, so that a three-dimensional workpiece is finally formed by cutting and bonding one layer at a time. LOM commonly used materials are paper, metal foil, plastic film, ceramic film and so on. This method can not only manufacture molds and models, but also directly manufacture structural parts or functional parts.

6.DLP laser forming technology;

DLP laser forming technology is similar to SLA stereo lithography technology, but it uses a high-resolution digital light processor (DLP) projector to cure liquid photopolymer and cure it layer by layer. Because each layer is solidified in a thin sheet similar to a slide, it is faster than the same type of SLA stereolithography technology. This technology has high molding precision, and can be compared with durable plastic parts by injection molding in terms of material properties, details and surface smoothness.

7.UV ultraviolet molding technology:

UV-UV molding technology is similar to SLA photocuring rapid prototyping technology, except that liquid photosensitive resin is irradiated by UV-UV, and it is molded layer by layer from bottom to top. There is no noise in the molding process, and the molding accuracy is the highest in the same technology. Usually used in jewelry, mobile phone shell and other industries with high precision requirements.

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