Analysis of 4 large-scale production processes of laser rapid prototyping

Knowledge sharing by Guangdong Shunde Teamwork Model Technology Co., Ltd, whom with over 20 years rapid prototyping experience.

Light curing stereoscopic shape (SL)

The technology uses a photosensitive resin as a raw material, and the ultraviolet laser under computer control scans the liquid resin point by point according to the contour of each layered section of the predetermined part, so that the thin layer of the resin in the scanned area is photopolymerized, thereby forming a part. A thin section. When the layer is cured, move the workbench and apply a new layer of liquid resin to the surface of the previously cured resin for the next layer of scanning and curing. The newly cured layer is firmly bonded to the previous layer and is repeated until the entire part is prototyped. The technical feature is high precision and smoothness, but the materials are brittle, the running cost is too high, the post-processing is complicated, and the requirements for the operators are high. Suitable for verifying the assembly design process.

FDM-Fused Deposition Modeling.

The key to the FDM process is to keep the semi-flow molding material just above the melting point (usually controlled at about 1 °C above the melting point). The FDM nozzle is controlled by CAD layered data to make the fuse material in a semi-flow state (the wire diameter is generally extruded from the nozzle at a diameter of 1.5 mm or more, solidified to form a thin layer of a contour shape, and a layer is layered to form an entire part model. Its process features direct production of engineering materials such as ABS, PC and other materials, suitable for different stages of design, can directly manufacture the final product. The disadvantage is poor surface finish.

SLS Setected Laser Sintering.

The method uses a CO2 laser as an energy source, and most of the modeling materials currently used are various powder materials. A thin layer of (100μ"200μ) powder is evenly spread on the workbench. The laser beam is selectively sintered according to the layered profile of the part under computer control, and the next layer is sintered after the completion of one layer. After the sintering, the excess powder is removed, and then the parts are obtained by grinding, drying, etc. At present, the mature process materials are wax powder and plastic powder. The process of bonding or sintering with metal powder or ceramic powder is also available, but It is still immature. This technology is more suitable for making wax molds for casting. Because of its poor precision and surface finish, it is not suitable for model verification and product production.

3D Printing (3DP-3 DIMENSION PRINTER).

The principle of the molding process is that the powder is sent out of the storage bucket by a certain amount, and then the powder that is sent by the drum is coated with a thin layer of raw material on the processing platform, and the two-dimensional layer obtained by the print head is sliced according to the 3D computer model. The information is sprayed with an erectile agent and a powder. After finishing one layer, the processing platform will automatically drop a little, the storage bucket will rise a little, the scraper will push the powder from the raised storage bucket to the working platform and push the powder flat, then spray the private agent, so that the cycle can get the desired shape. . The technology is characterized by fast speed (6 times that of other processes) and low cost (1/6 of other processes), the only way to print color parts. The disadvantage is lower accuracy and surface finish.

POLYJET light curing technology. Polyjet's printheads are similar to line printers, sliding back and forth along the X-axis, and an ultra-thin photosensitive resin is placed in the molding chamber. After each layer is laid, the ultraviolet light bulb on the side of the nozzle holder immediately emits ultraviolet light to quickly cure and harden each layer of photosensitive resin. This step reduces the post-processing required to use other technologies. Each time a layer is printed, the machined chassis inside the machine will sink extremely accurately, and the nozzles will continue to work layer by layer until the prototype is completed. Sophisticated tool software ensures that all nozzles work in harmony and can simultaneously spray the same amount of material onto the chassis. The advantages are: high precision and smoothness, and low operating cost. The disadvantage is that the material strength does not reach the material strength of the ABS.