Bencere roll burnishing tool can combine bores, od’s and faces in a single operation

The boring bar style roll burnishing tool uses a carbide roll that rotates on a precision bearing allowing the application of surface pressure both axially and radially to a component. The tool can even be used on pre-ground components that require a burnished texture level of finishing and very tight tolerances. An animation of the operational cycle of the tool showing ID, OD and face burnishing cycles is available. Visit www.bencere.co.uk and click on the tool photograph. The tool has two sets of springs to accommodate bi-directional loading. One set is located within the tool shank which enables the entire head assembly to deflect when the carbide roll is pushed against the surface of the part and a second spring is located behind the carbide roll. This allows the roll to deflect when the tool is fed directly onto a flat face or shoulder. The level of deflection can be adjusted via a set screw in the side of the shank or by increasing or decreasing the applied feed rate. Tools are available to burnish most materials up to 40 HRc from a minimum bore size of 16 mm with a selection of roll configurations and shank sizes to suit machine and customer applications. A recent application on an aluminium cylinder for an injection moulding machine with a diameter of 16 mm by 140 mm deep, the turning centre was run at 500 revs/min with a feed rate of 0.1 mm/rev to obtain a surface finish of 0.2 Ra micro-metre. The cycle time was 33 seconds.