“Introduction to FEA Method:

Machinery vibration problems cause additional loads on bearings, seals, couplings, and foundations and thus must be suspected of causing excess power consumption. Some of the literature is reporting that poorly balanced and misaligned machines are consuming up to 15 percent extra energy. Moore, Pardue, and Piety [1] report “Eliminating high energy vibration sources such as misalignment and imbalance can reduce machine power consumption 10 to 15 percent” An analysis by Xu, Zatezalo, and Marangoni from the University of Pittsburgh 121 yielded a heavy power loss for angular misalignment up to five degrees; in the case of one degree, it was 114 kWh/hp-yr. Reference [3] cites energy savings of 11 percent, attributed somewhat to a data collector manufacturer’s literature. Their presentation discussed measurements they have taken showing energy reductions of up to 60 percent. They claim to routinely find savings of 10 percent, with a minimum of 5 percent. Reference [4] discusses measurements that show a power loss of 2.3 percent for a loaded machine and 9.1 percent for an unloaded machine.

Additionally, experimental work that shows that the couplings consume energy was performed by Bortnem, Pray, and Grover of the Miller Brewing Company [5]. They connected a 10-hp motor to an 8-kW generator loaded to 7.6 kW and measured coupling temperatures as a function of misalignment. 

They found a linear coupling temperature rise proportional to parallel misalignment with a maximum of 41 °F for a 0.030-inch misalignment. When the alignment was as perfect as it could be measured with a laser ambient.

Recently, reference [6] presented results of a University of “Tennessee study that essentially finds no energy loss due to misalignment. The reference indicates a test procedure similar to ours except with one different coupling and a different machine foundation. They confined the amount of misalignment to the limits that the manufacturers recommend, whereas we considered much greater misalignments, as much as four times the manufacturers recommendations.

Energy losses of even 5 percent would cause major machinery maintenance changes, precision alignment and balancing, and wider use of vibration and infrared diagnostics. Due to these possibilities, the Navy sponsored an experimental study to scientifically determine if these energy losses could be confirmed. For those unfamiliar with conditions that give rise to gross misalignment, it can arise during installation whenever considerable care is not expended to assure its absence. In other words, it is a great deal of trouble to precision align new machines.”