Whitehouse Machine Tools offers heavyweight high precision HMC

Able to tackle workpieces up to half a tonne, machining them to very high precision levels in a nominal half-metre cube, the twin-pallet, 4-axis HMC was originally aimed specifically to fulfil a requirement in the American market. Over 100 have been sold in the US as well as in European countries including France, Italy and Germany, but none yet in the UK. The machine has been designed and built using "tried and tested designs and components used by leading global machine tool manufacturers", with this coupled with "a lower cost manufacturing base in Taiwan". The result, says Whitehouse, is that the company is able to build "a very high precision machine at a competitive price". A novel design feature is the machine's ability to be expanded retrospectively in the field, easily and affordably, from two to six pallets and from 80 through 120 to 220 tools in about one day. The result is said to be a highly flexible manufacturing centre that can grow with a user's business to allow extended periods of high efficiency, unmanned machining. Unusually, both 400 and 500 mm pallets can be used at the same time, offering additional flexibility for oversized parts and fixtures. The 12-tonne HMC boasts features that include thermal control of ballscrew nuts, thrust bearings, Y-axis servo mounting and the spindle cartridge by means of recirculating, chilled oil. The machine also boasts hand-scraped surfaces for mounting the ballscrew bearing blocks and roller bearing slideways, plus a host of other top-end features. An air/oil mist system delivers precise, pressurised lubrication to the ballscrews, roller guideways and spindle bearings, reducing thermal growth and allowing cutting accuracies of 2.5 microns and repeatability of 2 microns to be maintained. Circularity and roundness are quoted as 3.6 and 2.1 microns respectively, if the machine is installed in a temperature controlled environment. Top quality components used include the single-piece FCD600 castings for the spindle and pallets, Tsubaki ballscrews, THK heavy duty roller guideways, Tsudakoma rotary table (which provides a full fourth axis), BIG Plus 40-taper spindle (with face-and-taper contact coupling), Kosmek tapered cones on the automatic pallet changer (which also has high pressure air clean), and Fanuc 31i NANO control. The machine has a 15,000 rpm /22 kW direct drive spindle and one-second servo-driven toolchange, extending to three seconds when probes, special boring bars or heavy tools are being exchanged. Acceleration of 1 G takes axes to a 60 m/min cutting feed rate within the 640 by 610 by 680 mm working volume. Maximum workpiece size is 750 mm diameter by one metre high.