Red Seal Machinist Practice Exam

What is the function of an "indicator" in machining?

1. To measure speed of rotation

2. To check the alignment or runout of tools or workpieces

3. To sharpen cutting tools

4. To measure the temperature of materials

The correct answer is: To check the alignment or runout of tools or workpieces

An indicator, commonly referred to as a dial indicator or test indicator in machining, is primarily used to check the alignment or runout of tools and workpieces. This precision measurement tool is crucial in ensuring that both the workpiece and the tool are positioned correctly relative to one another, allowing for accurate machining processes. Indicators work by providing a visual readout of any deviations in alignment or movement, which can indicate issues such as wobble, warping, or misalignment. For instance, when setting up a lathe, an operator can use an indicator to assess if the workpiece is properly centered within the machine. Any detected runout can affect the machining operation, leading to poor tolerances and finish. The other options listed serve different functions in machining. Measuring speed of rotation is typically done with a tachometer, sharpening tools requires grinding machines or other sharpening equipment, and measuring the temperature of materials often involves the use of thermocouples or infrared thermometers. These tools have specific purposes that do not overlap with the function of an indicator.