ZEISS eMobility Solutions

Quality Assurance for Rotors & Shafts

Insights into Rotors & Shafts

The rotor is comprised of the shaft and the sheet stack with built-in permanent magnets. Due to the high performance and speed of the e-motor, the rotor has very tight shape and location tolerances that require inspection. The air gap between the rotor and the stator bore is one of the main parameters defining the e-motor’s performance and efficiency. It is also critical with respect to the safety and reliability of the motor.


Rotor Dimensions Measuring on ZEISS CMM with Long Stylus System

Dimensional Metrology

All dimensional features require measurement technology that is capable and accurate under the influence of the rotor’s magnetic field. The magnetic field can influence measuring results by deflecting the stylus or the inside of the probe. This makes a coordinate measuring machine that can measure the tightest tolerances with long and heavy stylus systems essential – ZEISS coordinate machines with active scanning technology are ideal for these requirements. Long stylus extensions make it possible to measure at each position of the rotor, keeping the probe far enough away from the strong magnet field to ensure stable,
accurate results all around the stator.

Shape & Contour Measurement

The shaft inside electric and hybrid vehicles requires very quick quality inspection, especially when it comes to shape and position tolerances due to the faster rotation speeds. As shaft geometries change and tolerances narrow, a coordinate measuring system makes it possible to remain within these narrow quantities while reducing throughput times and increasing predictability. A ZEISS coordinate measuring machine equipped with a highly accurate rotary table on air bearings and a diamond stylus kit is ideal for reliable results. Versatile coordinate measuring machines can measure shafts of all sizes.

Measurement of Type Form Characteristics on Shaft with ZEISS High Accuracy CMM

Porosity Analysis

Due to the increasing speeds in the electric motors, the demands on the strength and stability of the rotors are significantly higher. In order to prevent the rotor from breaking during operation, a certain porosity level must not be exceeded. Computer tomography from ZEISS is used to determine the size and number of pores in the rotor‘s short-circuit ring. The recorded 3D data are then analyzed and classified by ZEISS software using the porosity analysis.