Sensor Selection for Monitoring Complex Extrusion Gearboxes

Large extrusion gearboxes represent some of the most complex machines used in industry. They often utilize six (or more) shafts, a dozen gears and twenty or more bearings. In deciding how to monitor the health of these machines, it is useful to begin with the end in mind. What are the failure modes against which one must defend? For the complex gearboxes discussed here, one is predominately concerned with rolling element bearing failures and gear damage. For simple machines (fans, pumps, etc.) misalignment, imbalance and bearing failure are usually considered as the most likely faults that must be addressed. Impellors can sustain damage, resulting in imbalance and there can be dynamic effects (cavitation, blade pass pulsations, etc.) but in general these systems are relatively simple and can be effectively monitored using portable data collection devices on a monthly (or biweekly) basis. The bearings of simple machines are often very accessible, allowing the use of magnetic mounting the sensor, thus avoiding the cost of permanently mounting a separate sensor for each measurement location.