What is the function of the spindle on a milling machine?

The spindle on a milling machine is primarily responsible for spinning and holding the cutting tool. It acts as a rotating component that drives the tool at high speeds, allowing it to efficiently cut through the workpiece material. The spindle's design and capabilities directly impact the accuracy and effectiveness of the milling operation, as it provides the necessary rotational motion required for a variety of machining processes.

When a cutting tool is mounted onto the spindle, it must be securely fastened to ensure precision during the milling process. The spindle's rotation enables the tool to engage the material, thereby performing tasks such as drilling, contouring, and shaping.

The other options pertain to different functions or components of the milling machine. For instance, keeping the workpiece fixed is typically done through vises or clamps rather than the spindle. The coolant system is usually powered by a separate mechanism that helps manage heat during cutting, and measuring precision is conducted through measuring instruments and not directly by the spindle itself.