Fault diagnosis of linear bearings in brushless AC linear motors

Electric linear motors are spreading in industrial automation, because they allow for direct drive applications with very high dynamic performances, reliability and flexibility in trajectory generation. The moving part of the motor is linked to the fixed part by means of linear bearings. As in many other electric machines, bearings represents one of the most vulnerable part because they are prone to wear and contamination. In case of linear roller bearings this issue is even more critical as the rail cannot be easily fully enclosed and protected from environmental contamination, unlike the radial rotating bearing counterpart. This paper presents a diagnostic method based on vibration analysis to recognize the signature frequency of the fault.