Laser beam welding is a one-step process in which the heating of the plastic and the joining process take place almost simultaneously. In this case, a joining partner must have a high degree of transmission in the area of the laser wavelength and the other a high degree of absorption. Plastic laser welding machines are used to create substance-to-substance bonds. Prior to the welding process, both components are positioned in the desired end position and the backing pressure is applied. Inlike other other plastic welding methods such as ultrasonic welding laser penetration welding dates back to the mid-1990s. In industrial use, a characteristic of laser penetration welding is that the plastic is plasticized by the application of energy. Variants are contour welding, mask welding, simultaneous welding and quasi-simultaneous welding.