Incorrectly aligned shafts and the consequences of this are behind more than 50 % of all malfunctions in rotating machines. This increases unscheduled downtime and therefore production losses. This, of course, increases overall maintenance costs. In addition, misaligned shafts increase vibrations and friction, which can increase the energy consumption considerably and cause premature bearing and seal damage.

How accurately do you have to align?

The required accuracy depends mostly on the types of machines you have and the speed. Generally speaking, ±0.05 mm for the offset value (at 1500–3000rpm). However, it is important to refer to the machine’s or component manufacture’s specifications regarding this. That the coupling manufacturer specifies that their couplings can handle an incorrect setting of a few millimetres means, in principle, nothing regarding how accurately you need to align. This flexibility is to compensate for misalignment and forces during the start-up phase. When the machine rotates at the correct speed and temperature, it must still be correctly aligned. Otherwise seals and bearings are put under pressure by misalignment forces and wear out more quickly than necessary, even if the coupling lasts longer. Different couplings cope with misalignments better or worse depending on their design.

Correctly aligned shafts mean many improvements:

• Increased machine availability
• Increased service life of bearings and seals
• Less leakage and better working environment
• Less risk of overheating and secondary damage
• Less lubricant consumption
• Less vibration
• Reduced noise level
• Less risk of serious breakdowns
• Greater overall savings with fewer spare parts, lower energy consumption and less unscheduled downtime.