ORIGINAL ARTICLE A novel friction stir welding robotic platform: welding polymeric materials N. Mendes & P. Neto & M. A. Simão & A. Loureiro & J. N. Pires Received: 15 September 2013 /Accepted: 27 March 2014 # Springer-Verlag London 2014 Abstract The relevance, importance and presence of indus- trial robots in manufacturing have increased over the years, with applications in diverse new and nontraditional manufacturing processes. This paper presents the complete concept and design of a novel friction stir welding (FSW) robotic platform for welding polymeric materials. It was con- ceived to have a number of advantages over common FSW machines: it is more flexible, cheaper, easier and faster to setup and easier to programme. The platform is composed by three major groups of hardware: a robotic manipulator, a FSW tool and a system that links the manipulator wrist to the FSW tool (support of the FSW tool). This system is also responsible for supporting a force/torque (F/T) sensor and a servo motor that transmits motion to the tool. During the process, a hybrid force/motion control system adjusts the robot trajectories to keep a given contact force between the tool and the welding surface. The platform is tested and optimized in the process of welding acrylonitrile butadiene styrene (ABS) plates. Experimental tests proved the versatility and validity of the proposed solution. Keywords Friction stir welding . Robotics . Polymers . Force/motion control . ABS . Manufacturing 1 Introduction The promotion of manufacturing activities is probably one of the most effective ways to encourage economic growth and jobs creation. The question is how to do that? How manufacturing companies in developed countries can compete with low salaries? Much has been discussed around this over the years. However, there seems to be a consensus on the need to make manufacturing companies more flexible, producing what the market needs (small-series and customized products) and less dependent on the cost of labour. Industrial robots are key elements in flexible manufactur- ing [1]. The problem is that they are relatively complex machines that need to be reprogrammed to perform a new task. Generally, industrial robots operate in very structured environments, without the capacity to adapt to dynamic sce- narios. Thus, there is much research work to do in several different areas related to robotics, for example, in human- robot interaction and robot autonomy. At the same time, the application of robots in new and nontraditional manufacturing processes is another area for further research. This paper introduces and presents the concept and design of a novel friction stir welding (FSW) robotic platform for welding poly- meric materials. FSW was initially developed in the early 1990s for joining soft metals [2]. The welded seams produced by this method are free from defects: cracks, shrinkage and porosity. It also produces low distortion, which is a typical difficulty in fusion welding processes. This makes FSW a very attractive welding process. The traditional FSW process consists of a rotational tool, formed by a pin and a shoulder, which is inserted into the abutting surfaces of pieces to be welded and moved along the weld joint (Fig. 1). During the process, the pin is located inside the weld joint, softening the materials and enabling plastic flow as well as mixing materials. The shoulder is placed on the surface of the seam to create a smooth surface. Although this process is mainly applied to butt weld joints, other joint geometries can be welded. Aluminium, cooper, plastics, com- posites and dissimilar materials (for example, aluminium and cooper) are examples of materials that can be welded by FSW [3, 4]. The applications are many, but the following industries Electronic supplementary material The online version of this article (doi:10.1007/s00170-014-6024-z) contains supplementary material, which is available to authorized users. N. Mendes (*) : P. Neto : M. A. Simão : A. Loureiro : J. N. Pires Department of Mechanical Engineering, University of Coimbra, Polo II, 3030-788 Coimbra, Portugal e-mail: nuno.mendes@dem.uc.pt Int J Adv Manuf Technol DOI 10.1007/s00170-014-6024-z