Facing on a lathe is a machining operation that involves removing material from the end face of a workpiece to create a flat, smooth, and perpendicular surface. The facing process is often used to ensure that the end face of the workpiece is square with the axis of rotation, resulting in a well-defined and accurately positioned surface. This operation is particularly important when components need to be joined together or when precise measurements and fits are required.

Facing can be performed as a standalone operation or as a preliminary step before performing other machining operations, such as turning, drilling, or threading. It ensures that the workpiece has a properly aligned and clean end face, which is essential for accurate and reliable assembly of components.