Lasers Also Used to Join Plastics
Light and versatile plastics are increasingly replacing metals in automotive production, and manufacturing technology has to keep pace with new methods – such as the welding of two plastic components with a laser to form one sealed, compact part.
The trick of using a laser to weld two plastic components along a seam is surprisingly simple. Let’s follow the laser beam: It is emitted by a semiconductor or solid state laser and initially hits the first part, which is transparent to its infrared-range wavelength (to the human eye, the material can appear white or colored). It then hits the second part made of the same material, but this part is dyed in such a way that it absorbs infrared radiation. This second material absorbs so much energy at the point of contact that the two components melt and fuse at that spot. When it cools, the molten material solidifies into a homogeneous polymeric joint that forms an airtight bond between the two parts.
The non-contact, vibration-free laser method is so promising that new and existing manufacturing processes are being studied with a view toward using the laser as an economical, environmentally friendly and high-quality alternative. The laser technique could replace the adhesive bonding of plastic parts, for instance, and eliminating the adhesive would help protect the environment. Or it could replace ultrasonic welding, since it produces no abraded particles, and the electronic elements aren’t subjected to any vibration stress.
Laser-welding of plastic parts creates a homogeneous connection that guarantees airtight and watertight weld seams. Bosch is already using the technique to encapsulate gas pedal modules, which electronically acquires the position of the gas pedal in the footwell. In this case, the welded joint prevents moisture from seeping into the component. This laser welding process replaces rivet fastening and eliminates the need for a rubber seal.
The Bosch researchers’ art consists of understanding how to produce a high-quality weld seam. So far, this has been possible with components made of the same thermoplastic materials, like polyamides or certain polyesters. But development is focusing on combinations of different types of plastic. Because welding plastic doesn’t places any great demands on the beam quality of the laser, it suffices to use a low-maintenance diode laser with a power output of a few hundred watts. How the laser beam is guided across the part depends on the requirements of the weld seam: The laser beam might pass over the seam a single time, or there could be multiple, rapid exposures using a scanner system. The optimal process is developed for each individual application.
The non-contact, vibration-free laser method is so promising that new and existing manufacturing processes are being studied with a view toward using the laser as an economical, environmentally friendly and high-quality alternative. The laser technique could replace the adhesive bonding of plastic parts, for instance, and eliminating the adhesive would help protect the environment. Or it could replace ultrasonic welding, since it produces no abraded particles, and the electronic elements aren’t subjected to any vibration stress.
Laser-welding of plastic parts creates a homogeneous connection that guarantees airtight and watertight weld seams. Bosch is already using the technique to encapsulate gas pedal modules, which electronically acquires the position of the gas pedal in the footwell. In this case, the welded joint prevents moisture from seeping into the component. This laser welding process replaces rivet fastening and eliminates the need for a rubber seal.
The Bosch researchers’ art consists of understanding how to produce a high-quality weld seam. So far, this has been possible with components made of the same thermoplastic materials, like polyamides or certain polyesters. But development is focusing on combinations of different types of plastic. Because welding plastic doesn’t places any great demands on the beam quality of the laser, it suffices to use a low-maintenance diode laser with a power output of a few hundred watts. How the laser beam is guided across the part depends on the requirements of the weld seam: The laser beam might pass over the seam a single time, or there could be multiple, rapid exposures using a scanner system. The optimal process is developed for each individual application.
