WHAT IS THE BURNISHING PROCESS ? In the Escofier burnishing process, rotating hardened forming rolls or tools are pressed into the workpiece which thus also rotates.In the Escofier burnishing process, rotating hardened forming rolls or tools are pressed into the workpiece which thus also rotates. ADVANTAGES OF BURNISHING PROCESS The rolled workpieces have a better surface quality. Cost is reduced as work hardening may eliminate the need for heat treatment and due to the elimination of expansive precision ending. Very high accuracy, especially when used in combination with Escofier NC. THE ESCOFIER BURNISHING PROCESS IS USED FOR A VARIETY OF PURPOSES Improved structure and work hardening. The workpieces are less likely to suffer fatigue and can take higher stresses. In the process of moving material beyond the classic limit, the material is work-hardened in a manner which has a particularly favourable effect on resistance to fatigue caused by alternating forces, for example at a radiused recess at a change in diameter on a shaft which is subjected to alternating bending loads Rolling to finished dimensions or shape. Examples of this are rolling pre-cut gear teeth to the required final shape to minimise noise or to coin a spherical joint to bring the initial shape within tolerance. Burnishing or superfinishing. It is in the nature of the rolling process that a high quality surface finish is achieved, but the process can also be used to produce a super finish without altering shape, using tools with polished glossy surface.

BURNISHING PROCESS CONTROL Position controlled rolling :the machine stops the rolling operation when the distance between the centre of the forming roll and the centre of the workpiece has reached a predetermined dimension. This is also sometimes reffered to as Absolute Rolling. The volume of material displaced depends on the initial dimensions of the blank.Example: Coining a spherical blank.The purpose in this case is to finish form the part to the required size irrespective of the variations in the initial blank. Force controlled rolling: The machine stops when the resistance met by the forming tool reaches a predetermined value. This is sometimes called Relative Rolling . The volume of material displaced depends on the force applied and is therefore constant irrespective of the dimensions of the blank. Example: Rolling on cut gear wheels. The dimensions of the teeth will be reduced by a given amount. The dimensions of the teeth finally arrived at will depend on the initial dimensions COMPARISON OF BURNISHING MACHINE CAPABILITIES On conventional burnishing machines of this kind, the advance of the forming rolls is stopped when the distance between the centres of the forming rolls and the workpiece has reached a preset value or, alternatively, on machines with force control, when a certain force has built up. There is no practical way of controlled variation of the cycle up to the point where the limit is reached. With the Escofier numerically controlled rolling machines, irrespective of whether the limiting position is controlled by displacement or force, the preceeding sequence can also be controlled and the system can accommodate very complex rolling cycles. Furthermore, the sequences of forces and displacement in relation to time can be brought on to a display, which greatly assists fine tuning and there is also a facility for sorting parts based on predefined limits on actual values of parameters achieved.