Papers and Case Studies

Balancing: Environmental Causes on Unbalance of Rotating Machinery

Sometimes the biggest culprit of unbalance comes from the least predictable aspects, weather. Field balancing offers one solution.

Large fans for moving air are among one of the more universally used pieces of equipment at every industrial facility worldwide. Most often fans are used to move air past a heat exchanger to cool a liquid or gas. It is of utmost importance that these fans are operating correctly. Improperly balanced or dirty fans cause high vibration and decreased bearing life, which can lead to catastrophic consequences. Fan failure caused by unbalance can lead to downtime, serious accidents, or at worst, loss of life.

Balancing fans and other facility equipment can drastically increase bearing life and mean time between failure and repair. Even with a proper maintenance schedule however, rotating equipment can become unbalanced due to many other factors. One such factor is if a machine has been down for a period of time, dust and other natural debris can build up on the rotor and thus cause an unbalance. Corrosion, change in material properties with temperature, and normal wear can all lead to causing unbalance in a system.

With the season changing it is important to pay close to all rotating equipment. In climates where a daily freeze thaw cycle is occurring ice can form inside a rotor blade. Moisture can find its way into rotating machinery and cause ice to build up causing unbalance that can be hard to pinpoint. Thermal drift is also an interesting culprit in unbalance of rating equipment. An increase or decrease in operating temperature can cause various materials to grow or shrink. This causes a problem in that the once equal forces coming from the center of the rotor have now changed due to change in the moment of inertia of the system.

Environmental factors have the ability to create static and couple unbalance in a dynamically balanced system. Depending on the type of unbalance a 1-plane or 2-plane balancing procedure can be used in the field. For more information on environmental causes of unbalance or for assistance in field balancing your rotating equipment, email Red Wolf Reliability or call 970-266-9005!