There are many CO2 laser applications in the packaging industry. This is not surprising, as the materials most suitable for packaging are also those that are most suitable in composition and shape for CO2 laser technology.

In previous articles, we have seen the use of CO2 lasers on materials such as thermoplastic films, wood and some of their by-products such as medium density fiberboard, innovative packaging forms such as paper and cardboard. 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 laser welding of thermoplastics, a technology commonly used in the packaging industry. This process takes advantage of the fact that thermoplastics are easily processed once they are heat treated. In layman's terms, the welding process involves using a laser beam to heat the area where two thermoplastic pieces join until the melting point is reached.



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

■ It is a very fast process

■ Like all laser processes, it is extremely precise and easy to control

■ It leaves no residue or waste

■ It does not expose parts to thermal or mechanical stress because the heated area is localized and the process is not mechanical

■ It is highly automated and easy to integrate with other systems, whether digital or simulation systems

These properties 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 equipment, the production of components for the automotive industry, and the production of air-tight packaging for the pharmaceutical and food industries are examples of laser welding applications.



Plastic film laser welding

In packaging, laser welding is most commonly used for laminating thermoplastics. The laser of choice for this technology is the CO2 laser.

Direct welding is the type of welding best suited for thin materials. Unlike transmission laser welding, which is mainly used for 3D and molded parts, direct welding takes place directly on the material. This process allows for higher production speeds, thus increasing productivity while reducing production costs.



The most commonly used materials in the packaging industry are:

■ Nylon

■ Polyethylene

■Polypropylene

■ Acrylic (PMMA)

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 in the formulation, the speed at which the laser beam moves across the surface, and the intensity of the laser beam itself.
But generally speaking, the laser's effect on the surface of the material is stronger and weaker the deeper it goes. Adding carbon to thermoplastics can significantly increase the material's energy-absorbing capabilities, making lasers more efficient.

                     
Laser welding is ideal for producing original packaging that brings added value to the product, as it can handle complex shapes in a very localized way.

Plastic film laser welding equipment

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

In addition to the above items, a laser welding system should also include equipment for product management, loading and unloading, and powering the laser source.

                        
In summary, laser welding has a wide range of applications due to the versatility of laser technology. It can be adapted to fully digital processes or integrated with simulated production lines. This technology greatly reduces production costs and not only increases productivity but also improves product quality.