Benefits of laser shaft alignment

Shaft alignment improves machine reliability

When machines are properly aligned, friction is kept to a minimum. This not only reduces operating costs but also contributes to more sustainable operations. It also protects mechanical components from unnecessary stress. Bearings, seals and couplings last longer, reliability improves and the risk of unexpected breakdowns decreases. Lower vibration levels also create a safer and more comfortable working environment. Over time, well-aligned machines require fewer repairs and allow for longer intervals between maintenance stops.

Types of misalignment

There are two main types of shaft misalignment:

• Angular misalignment – Shafts meet at an angle rather than being parallel.
• Offset (or parallel) misalignment – Shaft centers are parallel but not colinear.

In practice, a mix of both angular and offset misalignment is the most common. The shaft alignment tool helps identify the exact condition so it can be corrected.

If left unresolved, misalignment can lead to serious problems such as increased vibration, damaged bearings and couplings, and unplanned downtime. You can read more about typical symptoms in our article “5 symptoms of shaft misalignment”.

Fixing shaft misalignment

To correct shaft misalignment, you should follow a clear step-by-step procedure to get accurate and lasting results. It begins with pre-alignment checks. This includes inspection and cleaning of the mounting surfaces and replacing old shims. Next, you do a rough alignment and soft foot check. Once ready, the measurement process is carried out using laser measurement equipment that collects precise alignment data. Based on these results, the necessary corrections are made, typically by adding or removing shims and adjusting the machine’s position horizontally or vertically. After the adjustments, a final verification ensures that the alignment is within the required tolerances.

If the alignment problem still cannot be resolved, a dynamic measurement may be required to determine whether external forces – such as pipe strain or thermal growth – are affecting the machine.

How accurately do you have to align?

The acceptable tolerance depends on the machine type and operating speed. As a general guideline, an offset value of ±0.05 mm is suitable for machines running at 1500–3000 rpm. Always follow the specifications provided by the machine or component manufacturer.

Different coupling designs can tolerate misalignment to different degrees, but accurate alignment remains the foundation for reliable operation. The coupling’s flexibility should not be used to set the acceptable alignment tolerance. Even if a coupling can handle several millimetres of misalignment, this is mainly to absorb movement during start-up. Once the machine reaches operating temperature and speed, the shafts still need to be correctly aligned. Otherwise, seals and bearings are exposed to unnecessary forces and wear out faster, even if the coupling itself continues to function.

External factors

All measurements with optical methods (including lasers) are affected by changes in surrounding air conditions during a measurement. Typical causes are differences in air temperatures, densities or air turbulence, air quality (moisture or dust), vibrations or movements on the object that the laser source is attached to, etc.

The laser system measures with a resolution down to 0.001 mm, but the accuracy and reliability of the measurement can be affected and decrease the precision of the measurement depending on the surroundings conditions. Repeatability tests are used to detect the impact and the user can then take different actions to optimize measurement accuracy. Adjustment of filter settings, avoiding or minimizing influence from error sources, increase stiffness in the mechanical brackets are typical actions to obtain high reliability in measurements.