Application of plastic film materials and laser welding

There are many applications for CO2 lasers in the packaging sector. This is not surprising, as the materials that are best suited for packaging are also the materials that are best suited to CO2 laser technology due to their composition and shape.

In previous articles, we have already seen some CO2 laser applications on materials such as thermoplastic films, wood and some of its byproducts such as MDF as well as paper and board for innovative packaging formats. The unique wavelength of the CO2 laser makes cutting, perforating, notching and marking particularly efficient and cost-effective.

The CO2 laser is an efficient and versatile tool for thermoplastic plastic laser welding, a popular technology used in the packaging sector. The process exploits the fact that thermoplastics are easy to work with after being heat treated. In layman's terms, the welding process involves heating the area where two thermoplastic sheets are joined with the laser beam until the fusion point is reached.

The process can be applied to different types of plastics, whether laminated or molded, opaque or transparent. Laser welding has many advantages:

• It is a very fast process

• Like all laser processes, it is very precise and easy to control

• It leaves no residue or waste

• It does not expose the part to thermal or mechanical stress, as the heating area is localized and the process is not mechanical

• It is highly automatable and easily integrated with other systems, whether digital or analog

These characteristics make it the tool of choice in industries where precision, cleanliness and the absence of thermal or mechanical stress are decisive factors. The production of biomedical devices or electronic devices, the production of components for the automotive industry, the production of hermetic packaging for the pharmaceutical and food industries are all examples of laser welding applications.

Laser welding of plastic films

In the packaging sector, laser welding is most often used for laminating thermoplastics. The laser of choice for this technology is a CO 2 laser.

Direct welding is the most suitable type of welding for thin materials. In contrast to transmission laser welding, which is mainly used for three-dimensional and molded parts, direct welding is carried out directly on the material. The process allows for higher production speeds and therefore increases productivity while reducing production costs.

The most commonly used materials in the packaging industry are:

• Nylon

• Polyethylene

• Polypropylene

•  Polymethylmethacrylate

The interaction between the laser beam and the material cannot be determined in advance. Many factors come into play: the type of polymer, the presence of additives added to the formulation, the speed at which the laser beam moves over the surface, and the intensity of the laser beam itself. But as a general rule, the effect of the laser is stronger on the surface of the material and weakens with increasing depth. Adding carbon to thermoplastics can greatly increase the material's ability to absorb energy, making the laser more efficient.

Laser welding is ideally suited to producing original packaging that brings added value to the product, as it works in a very localized way on complex shapes.

Plastic Film Laser Welding Equipment

Laser systems for laser welding require different components. The most basic are the laser source, the scanning head and the software system for programming and controlling the process.

In addition to the above items, the laser welding system should also include devices such as product management, loading and unloading, and laser source power supply.

In short, due to the wide range of uses of laser technology, laser welding has many applications. It can be adapted to a fully digitalized process or integrated with an analog production line. This technology greatly reduces production costs and not only improves productivity but also improves product quality.