Defect reduction in the production of electric drives by downstream compensation and space-resolved inspection

Improving the material efficiency in the production of electric drives is necessary as the electric automotive sector is growing very fast. Here, a method for early defect identification and downstream compensation, which allows defect reduction and consequently waste reduction, is presented. This reduces the waste motor parts (rotor stacks) and decreases the amount of rare earths to be recycled. A new inspection device was developed that allows a space-resolved in-line inspection of single rotor stacks as well as assembled rotors, in the same inspection station. This inspection device was realized as a demonstrator system, which is explained in detail in this paper. The inspection results are used as input for the downstream compensation methods, selective and sequential rotor assembly. Both methods combine stacks that are out of tolerances in such a way that the final rotor is within the specified limitations. Thus, low quality parts form a high quality assembly without having to scrap stacks and magnets.