Red Seal Machinist Practice Exam

What is a common application of plug gauges?

1. To measure the thickness of materials

2. To verify dimensional tolerances of holes

3. To check the surface integrity

4. To inspect the weight of manufactured parts

The correct answer is: To verify dimensional tolerances of holes

Plug gauges are specifically designed to verify the dimensional tolerances of holes. They consist of a cylindrical shape that fits into a hole to check if its diameter is within specified limits. If the plug gauge can be inserted into the hole, it indicates that the hole's diameter is within tolerance; if it cannot, it suggests that the hole is either too small or improperly machined. This application is vital in ensuring that parts fit together correctly and function as intended in assembly processes. Understanding this function is crucial in machining and manufacturing contexts, where precision in hole sizes directly affects the performance and safety of mechanical components. The other options, while related to measurement and inspection, do not accurately represent the singular purpose of plug gauges. They serve a different focus, such as measuring thickness, checking surface integrity, or inspecting weight, none of which align with the specific and critical role of plug gauges in tolerance verification.