Full Thrust thanks to measuring on machine-tools

Nowadays measuring of workpieces while clamped on machine-tools is state of the art in series-production more and more. At company RUAG big rings for the fans of jet-engines are manufactured by using touch probes and 3D Form Inspect software from m&h.

In a division of RUAG we were allowed to have a look on manufacturing of thin-walled fan-rings for jet-engines and to hear about their experiences with workpiece inspection while still clamped on the machine-tool. In Emmen plant, situated in the middle of Switzerland, about 1.000 employees are specialised on machining of complex parts made from aluminium and its alloys for aeroplanes and defense devices mainly.

„The strategy of RUAG is to manufacture critical parts of high complexity with reliable processes and at highest efficiency,“ Markus Graber, Teamleader Machining at RUAG tells. RUAG Emmen manufactures fan-housings for the jet-engine CF34-10E from General Electric, used at the newest generation of planes type Embraer 190 / 195, for example. These near-to-cylindrical workpieces have diameters about 1500 mm and a height of about 600 mm, but their walls are thin.

„The main problem was to adjust the run-out on the measuring machine. At the start we could not measure the parts on a CMM. Measuring by 3D Form Inspect from m&h while still clamped on the machine-tool was the only way to do the job,“ Markus Graber explains. The machining of the fan-housings is done on 2 machining-centres, type DMC 200 FD, with pallet-changers. Controlled by a Siemens 840D control the machines are equipped with m&h - touch-probes with infrared transmission via a small receiver mounted near to the spindle-nose. 3D Form Inspect software from m&h was used on this type of DMG machine-tools first time but it matched just from the beginning.

Beside the strong need of tough accuracy the fanhousings come up with a lot of complex geometries and surfaces curved in 2 directions, undercuts as well as hidden grooves and holes, which later-on are fixation points for drives and other devices of the engine. In order to be able to inspect them all 4 different touch-probes are used with different lengths and different diameters of touching balls as well as some with cross styli. M&h invented modular touch-probes with standard extensions available in lengths of 30, 50, 100 and 200 mm. The modules are made from stainless steel with a diameter of 25 mm only and can be screwed on one-another until close and rigid contact on their flanges and carrying its measuring...