During turning, the wedge-shaped cutting edge of the tool penetrates the surface of the workpiece while the workpiece itself undergoes rotational movement. The relative motion between the tool and the workpiece generates high stresses in the material at the machining zone, known as shear stresses. Initially, the workpiece material undergoes elastic deformation, and once the shear limit of the material is reached, material separation occurs. The geometry of the cutting edge influences the flow of chips.
The kinematics of hobbing involve multiple movements. The tool, which has a helical reference profile, undergoes rotational motion. This rotational movement of the helix results in a tangential translational movement. The teeth, offset tangentially, successively engage on the helical path of the tool. This movement is synchronized with the rotational speed of the workpiece. The translation of the helix on the tool and the rotation of the workpiece defines the manufacturing principle of hobbing.