Collaborative robotic MAG welding of structural frames with high geometrical variability for luxury retail shops

Automated welding is a well-known and widely adopted technology although it has been historically cost-effective only for large batches of products with low variability. Recently there has been an increasing interest in collaborative robotic welding systems for high-mix low-volume manufacturing, as they can provide partial automation of tasks whilst concurrently guaranteeing a flexible production environment. Within this research a specific industrial case study was assessed: the production of structural frames for luxury retail shops. These elements are the backbone support of furniture and decorative wall-mounts in high-end retail shops and are typically realized by manual Metal Active Gas (MAG) welding of Rectangular Hollow Section (RHS) profiles. Hence, the scope of this work is to provide an alternative robot-based MAG welding solution that can be integrated within a flexible job shop scenario to support the production of these structural frames. To devise the novel approach, a digital model of the cell was created to compare different configurations and understand a viable solution given the production requirements. A two-table configuration with a 400A MAG welding source coupled to a cobot mounted on a linear axis was designed and deployed in production, enabling significant reduction of manufacturing times given that frame fixturing is performed in masked production times. Process parameters were also developed to realize vertical-down welding on S275 RHS profiles further reducing manual post-processing operations typically required by horizontal manually-performed joints. Finally, the system was benchmarked within real-production cycles, demonstrating a cost-effective flexible manufacturing approach.