Ultraviolet Laser 3D Printing Process

Laser is one of the important inventions in the 1960s of the last century. It has the advantages of good monochromism, directivity, strong coherence and high power density. With the development of the industry, there are more and more types of lasers. According to its wavelength, it can be divided into: infrared laser, green laser, ultraviolet laser . Here mainly introduces the application and process of ultraviolet laser.

Ultraviolet laser wavelength of 355nm, belongs to the cold light source, can be better absorbed by the material, and the damage to the material is minimal. Ultraviolet lasers have a short wavelength. Taking the domestic Behring 3W ultraviolet laser as an example, its pulse width is 10ns-15ns, the action time on the material is short, can minimize the time of the thermal effect to protect the material, the spot is 0.5mm (the above data different manufacturers of lasers will be different), the spot is smaller and the energy is more concentrated. Compared with the high thermal effect of fiber lasers and the large spot of CO2 lasers, ultraviolet lasers have unique advantages in processing some special materials.

1. The principle and mechanism of ultraviolet laser 3D printing

The UV laser irradiates the liquid photosensitive resin through the pulsed ultraviolet wave (UV), and then the scanning galvanometer stack scans layer by layer in the X-Y plane from the bottom to the top and finally cures the forming. The forming accuracy is high (± 0.1mm), and it has a high degree of analog reducibility.The UV laser irradiates the liquid photosensitive resin through the pulsed ultraviolet wave (UV), and then the scanning galvanometer stack scans layer by layer in the X-Y plane from the bottom to the top and finally cures the forming. The forming accuracy is high (± 0.1mm), and it has a high degree of analog reducibility.

2. The UV laser mainly affects the parameters in 3D printing

Because the liquid photosensitive resin has the largest absorption coefficient of ultraviolet light, a lower light energy density can cure the resin, but because the absorption of ultraviolet light by the photosensitive resin follows the Beer-Lambert law, that is, the energy density of ultraviolet light decreases exponentially with the increase of transmission depth. Theory and tests show that only when the UV energy density accepted by the liquid photosensitive resin exceeds a certain threshold, the gel will be produced (the gel state is the critical state between the liquid and the solid state), so it needs to continue to output more than 200mw of continuous UV light in the curing process to make it cure, but how can we achieve better curing quality?

The curing quality of the resin is mainly determined by the scanning speed of the ultraviolet laser on the liquid surface, the spot size of the laser molding and the continuous output power of the laser. The scanning speed of the galvanometer directly affects the number of laser pulses and the contact time of the ultraviolet laser on the surface of the liquid photosensitive resin. If the scanning speed is too fast, the number of laser pulses may be insufficient directly, or the contact time is too short, resulting in a series of problems such as low curing hardness or curing failure. The size of the UV spot finally formed on the surface of the liquid photosensitive resin affects the thickness of the support and the thickness of the finished product, and if the laser spot is not round, it may lead to uneven energy distribution on the resin, resulting in a decline in the quality of the final molding or abnormal curing line width. Finally, the laser power, generally between 350mw-500mw continuous stable output power is the best, too high power may lead to black or yellow resin, too low power may lead to resin white or hardness reduction, if the continuous output power is unstable can also lead to curing line and curing depth anomaly and other problems. In summary, to get a better curing quality, we need to meet the following conditions for the laser: 1. Continuous and stable output power above 350mw; 2. Continuous and stable laser output pulse; 3. Good laser spot quality.

Xi'an Guosheng Laser Technology Co., Ltd. is a high-tech enterprise specializing in R&D, manufacturing and sales of automatic laser cladding machine, high-speed laser cladding machine, laser quenching machine, laser welding machine and laser 3D printing equipment. Our products are cost-effective and sold domestically and abroad. If you're interested in our products, please contact us at bob@gshenglaser.com.