A Y-axis on a CNC (Computer Numerical Control) lathe machine refers to the horizontal axis that is perpendicular to the X-axis and parallel to the bed of the lathe. The Y-axis controls the movement of the cutting tool along the width of the workpiece, also known as the cross slide.

On a CNC lathe, the cutting tool is typically mounted on a cross slide, which is mounted on a saddle that moves along the Y-axis. The movement of the saddle along the Y-axis allows the cutting tool to be positioned at different locations across the width of the workpiece. The Y-axis is controlled by a servomotor, which is connected to a ballscrew or leadscrew that converts the rotary motion of the motor into linear motion of the saddle.

In a CNC Lathe, the Y-axis is used in conjunction with the X-axis (which moves the cutting tool along the length of the workpiece) to provide full three-dimensional cutting capability, which allows the cutting tool to reach all areas of the workpiece. This is useful for various machining operations such as facing, turning, drilling, and boring.

Overall, the Y-axis is an important component of a CNC lathe machine, as it allows for precise control of the cutting tool’s position across the width of the workpiece, which is crucial for achieving the desired shape and finish of the part.