One of the key benefits of the WNT BT-FC system is the increased rigidity that is generated through face-and-taper contact, with the additional face contact counteracting any lateral forces and so greatly reducing axial deviation. For example, under heavy cutting conditions that generate lateral forces of 5 kN, a standard taper-only holder would deviate by over 100 micron; under the same conditions, a WNT BT-FC holder reduces that deviation to around 60 micron. Similarly, movement in the Z-axis is eliminated, which can amount to as much as 0.03 mm at high spindle speeds when using conventional toolholding systems, affecting accuracy and repeatability.
The design of the WNT BT-FC toolholders also leads to extended spindle life and reduced vibration. In high speed machining environments, spindle and toolholder wear is partly caused by oxidation of the spindle bore and toolholder taper, this oxidation is made worse by the friction between toolholder and spindle. With the addition of face contact, that friction through vibration is reduced, if not eliminated, which in turn reduces the possibility of oxidation occurring, thereby extending service life of both the spindle and toolholder. The reduce vibration also enhances the surface quality of the part being machined.
To maximise the benefits of the WNT BT-FC toolholders, they must be used with a BT-FC spindle, which many machine tool builders are now fitting as standard. The WNT BT-FC toolholders can still be used in standard BT spindles, but without the advantages of the recommended set-up.
The WNT BT-FC toolholders are available in a wide range of systems, including ER collet chuck, hydraulic chuck, shrink-fit adapters, cylindrical shank and shell-mill adapters. Depending on the style of holder chosen, they can be specified with either BT30, BT40 or BT50 tapers.
Says Tony Pennington, UK & Ireland managing director: “In the drive for improved productivity, toolholding plays an important role, alongside cutting tool and machine tool development. This is something that WNT has addressed over many years with products such as our hydraulic chucks, shrink-fit adapters and Centro P system. The BT-FC system is further evidence of our desire to ensure customers achieve the best performance from their machines and cutting tools.”