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 1500–3000 rpm). 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.
Cardan-shaft coupled machines
Many people wrongly believe that cardan-shaft-coupled machines do not need to be aligned as accurately. But an angular error in these machines causes a non-linear motion, which causes forces and vibrations in bearings, couplings and seals. In other words, shortens the service life. Make sure, therefore, that these types of machines are aligned correctly.
For all types of measurements, nothing is better than the conditions they are performed in. Regardless of the type of measurement system used. External factors such as temperature, air movement, dust, vibrations and measurement distances all affect accuracy. It is therefore important that the person who carries out the measurement is aware of these factors in order to be able to interpret the results correctly. The laser measurement system’s own resolution is, however, always 0.001 mm.