Quality-assured laser transmission welding of additively manufactured components with the support of an expert system

Laser Transmission Welding (LTW) is a well-known technique for joining conventionally manufactured high-volume thermoplastic parts, such as automotive injection molded parts. When LTW is used for additively manufactured parts (typically prototypes, low-volume production, or one-offs), the technology must be developed to overcome the difficulties in welding the parts, that result from the additive manufacturing process itself. Compared to injection molding, additive manufacturing results in an inhomogeneous structure with entrapped air within the volume. Therefore, there is a change in the transmissivity behavior in the weld area due to the additive manufacturing process. In order to make LTW available for additively manufactured thermoplastic components, a process chain was developed to support manufacturing. This process chain ranges from the optimization of the additive manufacturing process to the welding process and is supported by an expert system. For the evaluation of the manufacturing process chain, welding experiments with additively manufactured samples were performed. The transparent samples were welded to black samples with varying process parameters in overlap configuration and tensile shear tests were performed. The additive manufacturing process parameters were used to predict the transmittance of the transparent sample and the weld seam strength of welded parts using the expert system.