What is the main function of a knee in a milling machine?

The main function of the knee in a milling machine is to elevate the mill saddle. The knee is a crucial component that allows for vertical movement and adjustability of the saddle, which in turn holds the table where the workpiece is secured. By raising or lowering the knee, an operator can achieve precise vertical positioning necessary for accurate milling operations. This adjustment is particularly important when performing operations that require different depths of cut or when changing workpieces of varying heights.

The other options refer to different functions performed by other parts of the milling machine. For instance, holding the workpiece is typically done by the table or work clamps, the spindle's primary function is to rotate the cutting tool, and lateral movement of the table is usually managed by the cross-slide or table adjustment controls. Each component of the milling machine has its specific role, making it essential to understand the purpose of the knee for effective operation.