Why misalign a set of machines at the coupling when performing an alignment?

When aligning a set of machines, the goal is to ensure that the machines operate smoothly and efficiently. Thermal growth refers to the expansion and contraction of machine components due to temperature changes during operation. When machines operate, they generate heat, which can cause components, including shafts and coupling elements, to expand. If the alignment is performed without considering this thermal growth, the machines may be misaligned during operation, leading to increased wear, vibration, and potential failure.

By intentionally misaligning the machines during the alignment process, a millwright can compensate for the anticipated thermal expansion. This proactive approach helps ensure that when the machines reach their operating temperature, they will align correctly and operate within optimal specifications. This practice is crucial in preventing operational issues and extending the lifespan of the equipment.

Thus, misaligning machines at the coupling to account for thermal growth reflects a thorough understanding of machine behavior under operational conditions and is essential for effective maintenance practices.