Shaft misalignment detection by thermal imaging of support bearings

Traditionally misalignments in shafting systems have been determined by a vibration signature analysis. These misalignments are also responsible for temperature rise at the bearings and couplings. In this paper an experimental study has been made to early detect the presence of misalignment in systems, by measuring the temperature of the shaft couplings using a thermal imaging camera. The effects of load, speed and misalignment on the types of couplings and their temperature rise has been studied. It has been found that by monitoring the rate of temperature rise within the time constant of a coupling system, misalignment between shafts can be detected. In this study the experimentally measured time constant is found to be in the range of estimated time constant of the system from one-dimensional heat transfer models. In order to detect the misalignment in the system the temperature measurement of the coupling has to be done before it reaches its steady state value. Vibration measurements using both accelerometers and single point laser vibrometer at the bearing locations under different load and speed conditions have also been done to correlate with the thermal imaging. It has been found that the measured transient spatial temperature distribution on the couplings also indicate the presence of misalignment in the shafting system. The methodology proposed in this paper can be used in automated detection systems using thermography to detect misalignments from remote locations, where conventional vibration monitoring may be difficult.