What does the G96 code control in CNC machining?

The G96 code in CNC machining is used to control Constant Surface Speed (CSS). This means it maintains a consistent cutting speed at the surface of the workpiece, regardless of the diameter of the material being machined. By continuously adjusting the spindle speed as the diameter of the workpiece changes, G96 helps in optimizing the cutting conditions, ensuring that the tool operates efficiently and effectively, especially in turning operations.

This is particularly important for operations involving cylindrical parts, as varying diameters may lead to changes in surface speed if not properly managed. Maintaining constant surface speed helps to improve tool life and enhances the quality of the machined surface, reducing the likelihood of issues like overheating or poor finishes caused by inconsistent cutting speeds.

The other options do not accurately relate to the function of G96. Radius adjustment, length of cut, and tool change commands are associated with other G-codes and operations within CNC programming.