Types Of Shaft Misalignments

 What is Alignment?

• It is the process of positioning two (or more) machines that are coupled, so that Center lines of rotating shafts form a single line, when the machines are working at normal operating temperature.

Causes Of Misalignment:

• Thermal expansion - Most machines align cold.

• Machine vibrations.

• Forces transmitted to the machine by pipe or

• support structure.

• Soft foot.

• Direct coupled machined are not properly aligned.

• Poor workmanship.

Effects Of Misalignment:

• More than 50% problems are due to misalignment.

• Causes vibration on the machine

• Vibration destroys critical parts of machines like bearings, gears, seals, coupling etc.

• Breaks lubricant film inside the bearing and increase friction.

• Increases load on the bearing.

• Increase 2 - 17% power consumption.

• Generates heat inside the coupling.

Types Of Misalignment:

1. Offset Misalignment
2. Angular Misalignment
3. Skew - Combination Of Offset And Angular

Offset Misalignment:

• If the misaligned shafts centerlines are parallel but not coincident, then the misalignment is said to be parallel (or offset) misalignment.

• Offset (Parallel) misalignment produces both a shear force and bending moment on the coupled end of each shaft.

Angular Misalignment:

• If the misaligned shafts meet at a point but are not parallel, then the misalignment is called angular misalignment.