Pioneers in Machining Technology
The Japanese-made XEBEC range of high-precision, abrasive deburring tools made from aluminium oxide (alumina) is available in the UK through NCMT. The tools may be used on static platforms such as machining centres, mills, drilling machines and special-purpose machine tools, but are equally suitable for mounting on industrial robots. Versions are also available for hand-held power tools.
Comprising rods consisting of 1,000 alumina fibre filaments measuring just 10 microns in diameter, the tools have a self-sharpening cutting action on the tip only, there being no abrasive effect on the sides of the rods.
Dozens or hundreds of parallel rods go to make up a hollow, cylindrical tool. The rods are prevented from unduly splaying under centrifugal force by a metal sleeve whose ID is approximately the same as the OD of the tool. Only a short length of the fibre rods protrudes at any given time from the end of the sleeve, which is retracted by hand occasionally to compensate for rod wear. Periodic offsets also have to be entered into the machine tool control.
These are precision deburring, deflashing, finishing and polishing tools, more akin to an end mill than a wire brush, which is relatively crude in its application. Moreover, XEBEC claims that its method of growing the fibre filaments ensures that the alumina content is very high at 70 per cent by weight, compared with just 30 per cent in conventional, abrasive-impregnated nylon wires.
Fibres are available in four grades from coarse to fine. Despite their high metal removal rate, the tools wear slowly due to their high alumina content and also as a result of their resistance to high temperatures as well as to water- and oil-based coolants. The tools are equally capable of cutting dry.
XEBEC has also found a way of growing the fibres radially to form a stone-like tool similar to a mounted point, but with considerably better longevity and controllability when machining. Available in diameters from three to 20 mm, they are called Cross-Hole Deburring Tools, as this is deemed to be their primary application. They have a flexible shaft and are intended for efficient removal of burrs with a base thickness of 0.2 mm or less. There is also a solid brush version for finer burrs of under 0.1 mm diameter.
Novel deburring tool saves time, labour and money
In one application at Epsom subcontractor, W.E.C.S Precision Limited (WECS), a XEBEC tool is used in-cycle on an Okuma MA600 HB horizontal machining centre when making safety-related modifications to electric drive motor casings and reduction gearbox housings.
On the sand cast aluminium gearbox casing, two bores of 255 mm and 120 mm diameter are machined to within 32 microns and 25 microns respectively. There used to be a problem deburring the interface between the machined bore circumferences and the casting, as the position of the interface is not known to better than ± 2mm. It means that a mill cannot be programmed to remove the burrs consistently and it previously took an operator 10 minutes to finish each part by hand.
The job is now done in 90 seconds within the machining cycle by a XEBEC deburring tool from NCMT, resulting in considerable labour and cost savings. As the abrasive rod splays slightly, it covers the ± 2mm positional inaccuracies of the casting, producing a uniform deburred profile.
Allistair Bowmar, Lead Engineer at WECS responsible for the rail project said, “The advantage of the XEBEC system is that the whole of the filament is made of aluminium oxide. The self-sharpening rods last significantly longer than abrasive impregnated nylon brushes and surface finish can be controlled by a simple change to the tool length offset.”