the relative position between the tool and workpiece is decided by the correlative parameters of the tool and the workpiece. The machining heat
as a part of a machine
makes the machine deform during machining and influences the relative position and angle between the tool and the gear workpiece and reduce the accuracy of the products. It is very important to get the relation between the heat deformations and the relative position. It is also important to improve the both of hobbing machines to decrease or eliminate the machining errors by NC compensation and machine construre design.