A machinery solution offered jointly by two exhibitors for machining chucked gear components shows how production processes can be fruitfully combined. In the first part of the machine, the reference surfaces are machined by rotary turning, with options for outer, inner and face turning of soft or already hardened gear components with protruding surface roughnesses (Rz = 1 µm) (J.G. Weisser Söhne Werkzeugmaschinenfabrik GmbH & Co. KG, St. Georgen). An integrated component handling system is used to turn the workpiece and transport the material to the second part of the machine, where straight or helical toothing is given its final grinding (Kapp GmbH, Coburg).
Lasers are gaining steadily in acceptance as a manufacturing instrument. In fields where ultra-hard ceramic materials could hitherto be machined only by grinding, laser systems can now be integrated. One exhibitor of lathes uses the laser for hybrid outer machining of silicone nitride ceramics. The energy of the laser beam focused in front of the blade lowers the flow moisture point of the material concerned, enabling turning operations to be performed with diamond tools. Using lasers opens up further options for metallic materials such as extra hardening, adding hard-aggregate particles or micro-structuring local component sections. If hard-aggregate particles are used, tungsten or titanium carbides are employed, which with their ceramic properties and in particular their extreme hardness improve resistance to wear and tear. Interior machining is currently at the development stage (A. Monforts Werkzeug-maschinen GmbH & Co. KG, Mönchengladbach). In machining centres, laser systems can be used in parallel to classical metal-cutting tools, so as to provide 5-axis-machined component surfaces with micro-structures. Depending on the material being machined and the removal rate involved, users can choose between fibre, diode and pico-second lasers. One vendor, for example, exhibited the incorporation of a grained surface into the dies used in tool and mould construction (Sauer GmbH / Lasertec, Pfronten).
Selective application of thermal energy is also utilised when producing ball screws by means of dry hard whirling. The whirling tool used for this purpose is fitted with cutting inserts made of cubic boron nitride, which provide dry machining of the hardened round steel bar. The premium variant of this machine series is equipped with a solid granite bed, whose rigidity and thermal inertia prevents vibrations and dislocations. Excellent surface qualities are achieved (Reitec GmbH & Co. KG, Hagen).
For large workpieces, where multifarious machining tasks have to be carried out, one manufacturer is offering a manoeuvring-platform milling machine with a very reasonable price-performance ratio. Fast movements are assured by rapid traversing rates of up to 40 m/min. In the case of frequent position and tool changes, this means the non-productive time can be reduced. The key performance data of the main spindle (speed up to 5,000 min-1, power up to 30 kW and a maximum torque of 850 Nm) suffice for general metal-cutting operations (Union Werkzeugmaschinen GmbH Chemnitz, Chemnitz).
Specifically for difficult-to-machine materials, such as nickel and titanium alloys for the aerospace sector, one manufacturer is offering a machining centre that provides a cooling lubricant pressure of up to 150 bar. This means that even higher stock removal rates, where a large part of the power inputted is converted into thermal energy, are processed more efficiently. To enable turning operations to be carried out in the machining centre even on cubic workpieces that are not rotationally symmetrical, a round table has been integrated that permits workpiece diameters of up to 1,200 mm (Okuma Corporation, Oguchi, Aichi-Pref., Japan).
Whereas the achievable speeds for round tables had hitherto been limited to 1,000 min-1, one exhibitor was showing a bearing system that in directly driven round tables enables limiting speeds of up to 2,000 min-1 to be achieved. While retaining the requisite rigidity and accuracy, the frictional torque and the temperature obtaining inside the bearing have been reduced. This doubling of the limiting speeds is of particular importance when small workpiece diameters are required to be turned in machining centres at technologically appropriate cutting speeds (Schaeffler Technologies GmbH & Co. KG, Herzogenaurach, Ina Drives & Mechatronics GmbH & Co. oHG, Suhl).