NCCER Millwright Practice Exam

The most effective time to check for thermal growth alignment problems is immediately after stopping the equipment. This is because thermal growth can significantly affect the alignment of machinery. When equipment is operating, the heat generated causes components, such as shafts and bearings, to expand. This expansion can lead to misalignment that might not be evident while the machinery is running, as the parts are in their operating positions. By inspecting the alignment immediately after stopping, technicians can measure the positions of the components before they have a chance to cool down completely. This allows for a more accurate assessment of any discrepancies caused by thermal expansion. Once the equipment has cooled down, it may contract and revert to a different position, which could provide misleading indications about alignment issues that existed when the machine was hot. Examining the machinery before startup or at regular intervals does not effectively address thermal growth since alignment changes due to heat may not be apparent until the equipment has been running. Checking during operation can also be misleading as the machine's components are under thermal stress which can disguise alignment problems. Therefore, assessing the equipment immediately after it has been stopped is the most reliable method for identifying thermal growth alignment problems.