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Plastic Welding

Plastic Welding Technology Using Lasers


The basic principle of a plastic laser welding passes a focused laser beam through an upper,
laser transmission part to the interface of the two parts to be joined. The laser light is turned
into heat energy as it is absorbed by the lower joining part. The heat created at the interface
creates a molten weld seam and the two plastics become fused.

In general, ultrasonic welding, friction welding, hot plate welding, and welding using an
adhesive and screw, etc., have been used as representative methods for welding plastic
products. However, even though each method has its advantages, there have been calls for an
alternative method because of the shortcomings such as problems with appearance quality,
watertightness problem, burr & lint generation, production cost increase, product design
constraints, working environment problems, and low productivity.

The plastic laser welding technique has several advantages compared to the abovementioned
conventional plastic welding methods. In particular, it can resolve watertightness failure
(leakage), poor appearance quality problems, and burr & lint generation, and can achieve a
high bonding strength. It also has less constraints on installation space.

To minimize warpage and fundamental problems of the injection process and to ensure the
stable product quality in the production process, several technical factors have to be fully
reviewed and considered with the help of specialists from the design stage. It is known that this
will minimize trial-and-error in applying new technologies.

In successfully applying the plastic welding techniques to the mass production process, there
are several important parameters to consider as follows:

  • ⋅ Wavelength, output, characteristics and optical properties of the laser beam
  • ⋅ Transmittance, absorption rate, thickness, and color of the bonding material
  • ⋅ Beam transport device, pressure device and quality control device


  • Non-contact, No burr and lint
  • Resolves poor appearance with superior weld quality
  • Ensures high operation reliability and flexibility
  • Minimizes mechanical stress by inputting uniform heat energy
  • 2-D/3-D products can be welded

Applications of laser plastic welding

  • Automotive, electrical / electronic components
  • Transparent materials for medical products industry
  • Parts requiring high watertightness and pressure resistance
  • Industries and products that demand high appearance quality