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Do You Know Plastic Laser Welding?

Do You Know Plastic Laser Welding?


The main welding principle of plastic laser welding is "transmission welding". The laser (wavelengths 800 to 1950 nm ) penetrates the upper layer, and is absorbed in the depth range of 0.1-0.5mm below the lower layer, and then laser radiation is converted to heat.
Almost all of the thermoplastic can be used laser welding ---- ABS, PP, PS, PA, PVC, PBT, etc., and the welding strength can reach the base material strength.

 And which structure can not use laser welding?


The diagram shows the splicing welding, because the plastic melting temperature is low and mobility is poor. In this welding method, the welding strength and sealing can not be guaranteed.


The diagram shows the penetration welding, and is a theoretical welding possible, but in the actual welding process, the compression force, laser refraction and other issues is difficult to handle.


Color effects welding



In color plastic, the pigment or dye content is very important. When the pigment content is low, the fusion depth of the laser is relatively large, but the material itself does not form thermal damage. The resulting expansion volume can extend the melt contact time and ultimately increase the welding strength. Therefore, the absorption rate and the transmittance of materials can be adjusted by adding a filler or a pigment.

The most commonly used additive for white plastic is titanium dioxide (highly reflective material). Because white will reflect most of the laser rather than absorb, so white is not ideal for laser welding material color. Titanium dioxide type, addition volume, laser wavelength and specific process control are key factors to affect the ability of white materials welding.


Weld ability of different materials

Welding ways
Contour welding



During the contour welding process, the laser welding head or product driven by the XYZ axis, the laser running along the welding trajectory. In whole process , partial  materials melted, and  have no overflow materials. As the material welding surface without the overall melting process, the welding product height change small at the end.

The contour welding requires that the welding position of the upper and lower materials be fully fit, and the lager deformation will increase the design difficulty of the welding fixture.

The contour welding can be adapted to larger product sizes and complex 3D  structures, and can be quickly switched between different products.


Quasi-simultaneous welding


The quasi-simultaneous welding is a more efficient welding method. When welding scanner lens guide laser beam at a speed of more than 5 m/s along the welding path high-speed movement, which make the whole welding surface heat melting gradually. Under the action of the fixture pressure, the entire welding convex platform have a certain collapse.
The quasi-simultaneous welding  is similar to the traditional plastic welding, the weld seam position has molten outflow and the height of the product decreases. Due to the material collapse, so can overcome the material deformation.
The quasi-simultaneous welding can be adapted to product sizes is generally not more than 200mm * 200mm, and is usually used for planar welding. As a result of the overall heating, the efficiency is higher than the contour welding.

Laser source of Plastic Laser Welding: Laser Diode
Suitable for the precision welding applications of electronic sensors and medical devices etc.


Sample shows:


Any problem about Plastic Laser Welding , welcome send E-mail to us at international@uwlaser.com.