Red Seal Machinist Practice Exam

What is the primary function of a plug gauge in quality control?

1. A gauge used to check the dimensions or form of holes

2. A tool for measuring large surfaces

3. A device to evaluate the hardness of materials

4. A measuring tool for linear distances

The correct answer is: A gauge used to check the dimensions or form of holes

The primary function of a plug gauge in quality control is to check the dimensions or form of holes. A plug gauge is specifically designed to fit snugly into the hole being tested, verifying whether its diameter meets the specified tolerance. This is crucial for ensuring that parts will fit together correctly in assembly or meet functional specifications. In the context of quality control, plug gauges serve as go/no-go tools. The "go" side of the gauge should easily fit into the hole if it meets the required specifications, while the "no-go" side should not fit at all. This method provides a straightforward way to determine if the hole is within acceptable limits for its intended application. Understanding this function helps ensure precision in manufacturing processes, directly influencing the quality and reliability of finished products. Other items such as tools for measuring large surfaces, devices for evaluating material hardness, or general measuring tools for linear distances serve different purposes and would not effectively assess hole dimensions.