How can the film thickness sensors be calibrated?
A14. Firstly, the method works by analytically deducing the oil film thickness from reflected ultrasonic signals. Therefore there is no need for a separate calibration exercise to relate oil film thickness for a specific bearing case. However, as with all measurement devices, calibration of the sensors is an important part of their operation. There are a number of ways the sensors can be calibrated – a separate document is provided for this. A reference signal can be taken periodically (at a known oil film thickness or when the bearing is disassembled), an intermediate interface (or notch) can be included in the ultrasonic path and this reflection used to calibrate, alternatively we have developed a self-calibrating sensor that measures both phase and amplitude together and uses the relationship between the two signals to calibrate.
