NCCER Millwright Practice Exam

What is an important consideration when selecting materials for shims?

1. Cost and availability

2. Thickness and compression factor

3. Color and appearance

4. Durability and weight

The correct answer is: Thickness and compression factor

When selecting materials for shims, thickness and compression factor are critical considerations because they directly affect the shim's fit and performance in an application. The thickness of the shim must match the requirements of the assembly, ensuring it provides the necessary support and alignment. If a shim is too thin, it may not adequately fill the gap, leading to misalignment or instability. Conversely, if it is too thick, it can create issues with the operation of the machinery. The compression factor is also important, as it defines how much the shim material can deform under load. Proper understanding of the compression characteristics ensures that the shim won't compress excessively, which could lead to loss of support or failure over time. This consideration is essential, especially in machinery where precision and stability are necessary for safe and efficient operation. Other factors like cost and durability can play roles in material choice for shims, but they are secondary to the technical requirements dictated by thickness and the need to withstand operational stresses.