Laser Plastic Welding
What is Plastic Laser Welding and how does it work
To weld plastic materials with the laser, a welding process called «in transparency» is used. To apply this technique, the product must consist of a transparent part to be placed on top (lid) and an absorbent part to be placed underneath (container). The heat generated by the absorption of the lower part brings the polymer to the set welding temperature, which creates the conditions for there to be the necessary thermoplastic interpenetrations.
The wavelength of the laser and the absorption characteristics of the two materials play a fundamental role in the success of the welding.
Application sectors Plastic laser welding
Automotive The Automotive is a sector where the use of laser welding of plastic materials is widespread, both for the creation of dashboards and interiors, and for the functional internal parts of engines, power packs or hydraulics. More specifically, widespread applications are for tanks and enclosures, sensors, optical groups, dashboard components and key groups.
Medical The medical is a sector in which laser welding of plastic materials is used both for the construction of bodies and containers for medical devices, and for the consumables related to various applications. More in detail, widespread applications are for microfluidics, sterile consumables, boxes or hermetic groups of medical devices, biochips.
Electrical and Electronics Electronics is one of the fields where laser welding of plastic materials is widely used, even on a large scale. Main applications are in the electrical and consumer electronics fields: protective and hermetic boxes and assembled groups, components, sensors.
Textile Laser welding of plastic in textiles is mainly used to carry out technical fabrications such as the welding of non-woven fabric or the creation of filters and membranes.
Material and Plastic laser welding
The materials to refer to for laser welding of plastics are thermoplastic polymers.
These are divided into two categories:
- Amorphous thermoplastic polymers
- Semi-crystalline thermoplastic polymers
The amorphous ones are transparent to laser radiation even for large thicknesses. On the contrary, semicrystallines have an intrinsic absorption linked to internal diffractive phenomena (scattering), which grows with thickness. In addition, the addition of additives to polymers (inorganic fillers, pigments, glass fiber, carbon fiber), can change the absorption characteristics of the radiation, making it generally more absorbent.
In general, thermoplastic polymers of the same family can be welded together.
However, the table on the right shows the weldability even between polymers of different nature, giving an evaluation of the effectiveness of the combination.
Types of Plastic Laser Welding
The three applicable plastic welding strategies are:
Contour welding: with X-Y movements, flexible and with welding speed in the order of 10 m / min.
Quasi simultaneous welding: using an ultra-flexible galvanometric head with a welding speed of 10 m / s.
Simultaneous welding: using special optics (linear, ring, radial or custom), dedicated to specific applications and with welding speeds of less than 1s.
Process Control on Plastic Laser Welding
Laser welding of plastics is flexible and makes it possible to control the process parameters in a precise and timely manner. The software allows you to monitor on-line: laser power, welding time, welding speed, workpiece temperature (in systems with pyrometer) and clamping pressure of the pneumatic clamping equipment.
All process data will then be made available in user-specific reports and used by the software for pass / fail assessments of the product on the production lines.
Why prefer a Plastic Laser Welder to other technologies
Plastic welding is an increasingly widespread application, as it allows the creation of components with complex shapes, with excellent aesthetic results and without the need for post-process processing (no debris).
It also allows you to weld without contact, vibration and, thanks to the control of process parameters, with very high repeatability.
Additional features of laser welding of plastics are the high mechanical strength and homogeneity on the profile, which makes it ideal for applications where the tightness of processing is important.
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