Butt Welding of Transparent Polyamide (PA11) with 1.94um Fiber Laser

Laser welding of polymeric products has been manufactured for more than 20 years. During that time polymer welding has developed a lot. In spite of that, there are still some limitations in applying the process to the industry. Typically welding has been made in lap joint configuration with black and clear parts because of optical properties of polymers. When using ~1 µm lasers, the absorbing and transparent partners are needed. Previously visually transparent materials have been welded in lap joint configuration using infrared absorbers with ~1 µm lasers. Recently new fiber lasers have introduced wavelengths which can have interesting optical properties for polymers. For example, 1.94 µm laser has volume absorption through the whole material thickness on selected polyamide 11 (PA11) polymer material. This makes it possible to use butt joint for welding of polymeric components. When butt joint can be introduced, it will enable more possibilities in using polymer welding in the industry. A joint between two clear components without any additional absorbers can also be introduced with these new wavelengths and it will also decrease the costs and enable new applications when no infrared absorbing additives are needed or accepted. This paper presents results of butt welding of transparent PA11 using TWIST method with 1.94 µm fiber laser. Weld quality is evaluated visually and by comparing weld tensile strength to base material tensile strength.