ALUMINUM CASE HISTORY
This aluminum company had been experiencing vibration instability on their ingot preheat furnace recirculation fans. Robinson field technicians were called in to determine the cause and recommend solutions. A series of vibration measurements were made with the fans running under normal operating conditions.
Robinson determined the cause of the instability was vibration interaction (‘beating”) between adjacent fans operating at almost identical speeds within each furnace.
Each furnace had three identical recirculation fans. The center fan’s speed was reduced which broke up the beat pattern and stabilized the operation.