Coating of a large Francis runner with HVAF technology
The francis runner of a powerplant in India must be coated to avoid damages due to abrasion. To archive a high coating quality, this runner was coated with the new efficient and high-performant HVAF (High Velocity Air Fuel) technology.
The size of the work piece (4.4m diameter, 40t weight), the safety risk for the operator and the complexity of the gun movement makes the manual coating impossible. Therefore, a typical industrial robot must be used.
The HVAF technology has high requirements for the precision and equality of the coating application. Additionally, the gun angle to the surface should be as perpendicular as possible, but collision issues make this impossible in certain areas. And due to the size of the workpiece, the robot moves at its axes limits.
The solution of these various problems was to combine the collision control, the axis limit control and the path smoothing in one sophisticated algorithm.
This francis runner was only the second completely coated with the HVAF coating system worldwide.