• Industry   Chippings, power, precision

Chippings, power, precision

New materials such as carbon fiber reinforced plastic are becoming established in aircraft and engine construction, though metal alloys will continue to serve as the main materials for a long time to come. However, the development of materials is making increasing demands in terms of the capacities of machining equipment and processes. aerotec’s Nikolaus Fecht conducted an exclusive survey to find out just how the machine tool industry is facing up to these challenges.

Machining centers in XXL format for the aerospace industry are among the specialities of Handtmann A-Punkt Automation GmbH based in Baienfurt, which adapts its equipment to a wide range of applications by means of different machining heads and drive spindles. Gantry high portal machining centers are particularly in demand, for example. As Manager Bernard Feith outlines: “We build machines in widely diverse sizes. Our biggest double spindle center has a table measuring 4.40 meters in width and 37 meters in length.”

Large-volume structural components can be processed on universal machining centers such as the UBZ HP, which is fitted with tables of the appropriate size. These machines have a fixed portal with a movable table, with high-speed spindles moving at 24,000 rpm being used for milling aluminum, for example. Spindles with a low rotational speed (less than 1000 rpm) and high torque are more suitable for machining titanium or high-strength steel.

HD profile machining centers are a good choice for cost-effective processing of long, straight profiles such as seat rails or cross members since they can be optionally fitted with a fixed or movable portal along with movable vises or table. Boeing and Airbus use such equipment fitted with 45 – 110 kilowatt spindles. The horizontal machining of panels, profiles and cross-members is also taken care of by HBZ horizontal machining centers fitted with a movable portal with standing, vertical table (max. seven by two meters). The HBZ AeroCell which Handtmann developed in collaboration with aviation supplier Asco Deutschland GmbH is suitable for processing aluminum structural components. The advantage of its design is that chippings fall directly downwards during horizontal machining and are efficiently transported out of the machining area. The company also fits the AeroCell with high-performance drives (spindle output up to 195 kilowatts, max. 30,000 rpm) so as to obtain a high level of cutting power.

What about new materials such as carbon fiber reinforced plastics? The centers used here are lighter than machining centers for aluminum or titanium and are also fitted with different head and spindle types. Dry machining is applied to CFRP. These centers also have special suction facilities, though wet machining exists in this field too, using splash water. This type of center has special filter fittings for recovering the CFRP from the waste water.

Dörries Scharmann Technologie (DST) has generated around 30 percent of its sales in the aerospace sector over the last 15 years.

Clearly, centers for the aerospace sector often require considerable consulting input. Feith: “We don’t just sell a machine, we sell a whole consultation process.” Handtmann employs a large pool of application technicians and engineers who are involved in supporting customers in their choice of tool. The aerospace sector is very important for Dörries Scharmann Technologie GmbH (DST) in Mönchengladbach: it has generated around 30 percent of its sales in this area over the last 15 years. A whole team of key account sales consultants, project engineers, construction engineers and technologists are lined up to support aviation clients.

According to DST, the company ranks as the leading supplier of machined integral aluminum components, and sizes requested are on the increase. Machines of the Ecospeed series are generally opted for, depending on component size. The parallel-kinematic machining head Sprint Z3 is at the heart of this series. One example here is Moyola Precision Engineering based in Castledawson in Northern Ireland, who have invested heavily in business operations as a first tier supplier of aircraft structural components over the last four years. The company’s main focus is on three 6-axis high-speed Ecospeed F and HT machining centers.

Large gantry machining centre Type DMC 210 U for structural components up to 16 tons.

The Irish supplier draws on an Ecospeed F 2060 with a clamping capacity of two times six meters. “We are able to make significant savings using the method of nested arrangement. “This technology increases our profit margin on every part we produce – in fact it can even determine whether or not an order is profitable.”

The Japanese manufacturer Yamazaki Mazak offers a very broad range of machines for the aerospace industry. According to Marcus Burton, Group Managing Director Europe of Mazak UK  Ltd. in Worcester (UK), potential candidates are vertical CNC turning centers or 5-axis machines (for the high-speed processing of aluminum parts, for example). Sophisticated turning and milling centers are suitable for complete machining of turbine housings and blades. Burton: “These are multifunctional machines which are able to combine turning and milling in a single operation – including 5-axis processing.” As a new highlight, Mazak presented the Hyper Variaxis 630 at METAV 2010.

Over a range of 630 millimeters (diameter) this machine cuts 500 millimeters with a 5-axis simultaneous control system. Linear and direct drives in the axes ensure very fast machining (rapid traverse: 8,000 to 80,000 millimeters/minute in X/Y/Z direction). “Components of various shapes can be manufactured using this specialized machine,” explains Burton. From its series of vertical machining centers with travelling column, Mazak also presented the VTC 800/30 SR for machining aluminum structural parts. Powerful CNC turning centers specifically designed for heavy chipping are used for processing large, long shaft components, such as the Slant Turn Nexus series for large components (up to 1,040 millimeters diameter, max. 3,200 millimeters in length).

How is Mazak responding to the trend towards new materials? “The aviation industry is already confronting us with requests for the relevant manufacturing techniques to handle materials such as Inconel and titanium,” explains Burton. “We prepare our machines for this more demanding type of material by opting for special powerful spindles and drives.”

The DMG machine tool group (Bielefeld) runs a “Center of Excellence” for its aerospace business which acts as a direct contact for the aviation industry.  Its subsidiary Deckel-Maho offers modules for the aviation and aerospace industry which allow the standard machines of the Pfronten-based company to be individually adapted to airframers’ needs. The modular structure of the duoBLOCK machine series is not suitable for the HPC or HSC field but permits combinations such as milling and turning in a single setting.

Spindle-power up to 100 kW
Special aerospace spindles fit in the mounts of all machines in the longitudinal travel class of 800 to 1,600 millimeters. These aerospace spindles have an output of up to 100 kilowatt at 180 Newton meters and a maximum torque of 15,000 rpm with the HSK A100 mount. With their intrinsically stiff construction, the spindles also allow HSC and HSP processing of materials with low machinability such as titaniferous alloys. Here is an example of use: face milling of a component made of AlZnMgCu1.5 on a 5-axis universal machining center of the type DMC 100 U with A axle provided a chip removal rate of about 8,000 cubic centimeters per minute at a spindle rotation speed of 11,000 rpm.
- Nikolaus Fecht -

German Summary
Zwar etablieren sich im Flugzeugbau
bereits neue Materialien wie CFK , dennoch werden Metall-Legierungen noch lange der Stoff sein, aus dem Flugzeuge und Triebwerke gemacht sind. Die  Werk-stoffentwicklung stellt dabei immer höhere Ansprüche an die Leistungsfähigkeit von Bearbeitungsmaschinen und -prozessen. Wie die Werkzeugmaschinenindustrie mit diesen Herausforderungen umgeht, fand aerotec-Mitarbeiter Nikolaus Fecht in einer exclusiven Umfrage heraus. Der deutschsprachige Beitrag ist nachzulesen auf www.aerotec-online.com

Weitere Beiträge