Laser beam Weld seam Transparent joining part Absorbing joining partMelt zone Laser welding concept. In laser welding of thermoplastics, sometimes referred to as «laser transmission welding» or «through transmission IR welding» (TTIr), transparent and absorbing parts are bonded together. The laser beam penetrates the transparent plastic and is convertedto heat in the absorbing plastic. Since both parts are pressed together during the welding process, heat is conducted from theabsorbing to the transparent plastic, allowing both materials to melt and create a bond. Internal joining pressure is also generatedthrough the local warming and thermal expansion. The internal and external joining pressures ensure strong welding of both parts.
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