ABSTRACT
Robots are increasingly used to replace human beings in the thermal spraying technique, not only for high-quality coatings but also to protect the operator’s body against harsh spraying conditions like elevated temperatures, dangerous gases, and loud noises. The robotic arm controls the movement of the spraying torch relative to the workpiece surface. High flexibility and reproducibility are achieved due to the automation with guaranteed quality coatings and cost-effectiveness. During the spraying, the kinematics of the process has remarkable effects on the final mechanical and tribological characteristics of the deposited coatings. The trajectory of the robot significantly controls the mass and heat transfer rate to the coating or the substrate. Furthermore, the deposition efficiency is controlled by the process kinematics as it directly affects the impacting particle state.
The continuous developments in thermal spraying technologies give birth to new application fields, and more complex geometries can be easily coated. Achieving uniform and defect-free coating deposits for these complex geometries is still an exciting and active research topic. The use of reliable and accurate robot programs is the need of the hour to ensure high-quality coating properties with uniform thickness, surface roughness, microhardness, porosity, etc. In this regard, robot programming plays a vital role, and it needs to be optimized further for complex geometries to obtain better quality and economic coatings with high dimensional accuracy. Although at present, the majority of the operations in robot programming are performed by online methods. Offline programming is supported and performed by applying the virtual cells, where the spraying kinematics are optimized and can also be simulated and are getting attention in thermal spraying, particularly for the coating of complicated geometries. With this objective, the offline programming approach has been integrated with proper simulation tools to generate a virtual blueprint of the entire coating process. This chapter will elaborate on the role of kinematics and the importance of robot offline programming during thermal spraying.
