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Technologicallatitude includedThe example of Aerotech Peissenberg GmbH & Co. KG, a leadingmanufacturer of components for jet engines and turbines, makesone thing clear: A blisk production that meets all manufacturingand economic requirements is also possible on a few machineswith standard kinematics - and also much more flexible.

Aerotech Peissenberg (subsequent-Iy called just Aerotech), foundedin 1971 by the MTU Aero Engi-

nes jet engine manufacturer, is nowpart of the Drosten group and suppliesjet engine and aircraft manufacturersthroughout the world, induding Rolls-Royce, EADS and the Safran group. Thecompany has progressed from the ear-lier dominating preproduction of engi-ne and mounted components to be-come a renowned and qualified supplierof preassembled, fully-certified dass lAcomponents. In addition to compressorand turbine rotors, and blisks, Aerotechmanufactures not only rotating andstatic sealing rings, but also housings,shafts and hubs for drives and turbines,through to complex split cases for heli-copter turbines with adjustment holesfor the vane guides and blade guides ofthe turbines. These largely rotation-symmetrie parts have diameters thatrange from approximately 300 mm tomore than 650 mm. Prismatieally for-med, highly loaded small parts, such ascomponents for engine nacelles, moun-ted parts, statieally heavy loaded struc-tural elements or pylons, are, however,also an important business area.

For this production spectrum, theheavy-duty cutting of high-temperatureresistant niekel-base alloys or titaniumand forged parts be comes an essentialcare competence at the Peissenberg 10-cation: "We start where others stop!"could be Aerotech's slogan.

In view of the worldwide increasingneed for aircraft - and thus also jet en-gine components - Aerotech has beenworking on doubling its manufacturingcapa city compared with 2005. This goalshould be achieved in 2010. A stepalong this path was the investment innew 5-axis simultaneous milling cen-

38 aerolec. june 2009

ters. To remain flexible in the produc-tion, Aerotech prefers machines withstandard kinematies on whieh the pris-matie single and series parts can also bemanufactured, such as blisks, by far themost technologieally demanding partsproduced at Peissenberg. Together withthe machine acquisition depanment,the technology specialists at Aerotechinvestigated the eligible machines fromvarious vendors. The dear decision wasmade in favor of the GSI000/5T, a5-axis simultaneous milling center ma-de by Alzmetall and equipped with aCNC of the Sinumerik 840D series.

Extreme rigidity and precisionKarsten Riemer, section leader for tech-nology development and machine ac-quisition, justified this decision: "Thecomplete construction of the GS100015T,its drives, dynamies, precision and rigi-dity elevate this machine from the fieldof the competitors and also permit thelong-term rational and economie pro-duction at the highest technologiealle-vel." The extreme rigidity and precisionof the machine result from an interna!,but also double-guided driving carriageframe. The double guide means that notjust an evasive counter movement re-sults in the side walls, but also an s-form shaping. Its side displacement isless than for top-mounted travel gearsby a factor of approximately two. Itsconstruction principle makes the ma-chine significantly more rigid than otherdesigns.

The Y-axis also consists of a fully-symmetrie, two-sided double-mountedguided travel gear in gantry operation.The induded eight-fold mounted spind-Ie is moved in the Z direction. The sym-metry of the frame construction and thedrives compared with the lOol axis re-

German Summary

Blisks- aus einem Stückgefertigte Turbi-nenschaufelräder - stellen allerhöchste

Anforderungen an Fertigungsgenauigkeit,Oberflächenqualität und Zuverlässigkeitder Werkzeugmaschine.Deshalbkommenhier häufig Speziallösungen zum Einsatz.Doch eine Blisk-Fertigung,die fertigungs-technisch wie wirtschaftlich allen Anfor-

derungen gerecht wird, ist auch auf eini-gen wenigen Maschinen mit Standard-kinematik möglich - und außerdem vielflexibler. Der gesamte deutschsprachigeBeitrag ist nachzulesenauf www.aerotec-online.com

duces all positioning, tipping, pitch andyaw errors to the mechanieal minimumcurrently possible, and the cuttingcounter forces are dissipated very uni-formly in all directions. The A- and C-axes lie in the workpiece, where theA-axis is driven on both sides with

highly-dynamie tarque motors in trueJanus operation. With :t 130 degrees,the swivel area of the A-axis is compa-ratively very large: -120 to +30 degreesare usual. "The large and symmetricswivel area of the A-axis so avoids the

need for some damping actions", com-mented Herben Leg!, responsible atAerotech for the NC programming,"and relief cuts can often simply be per-formed from the opposite side."

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The rotation axes also provide anautomatie, offset-free clamping, that fi-nally takes the drive controlloop fromthe chain of vibration-free elements.

This means the vibrations caused by thetool are less than for axes held only bythe drives. This significantly reduces thetool wear, in panieular for roughing.

Such an uncompromising quality-,precision- and performance-orienteddesign is found in the complete machi-ne. In cooperation with the SiemensMechatronic Support, Alzmetall alsosubjected the mechanieal design anddrives to a comprehensive mechatronieoptimization. The consequent extreme-Iy rigid overall behavior of the machineis the reason for maximum precision

and dynamie response at the tool tip -ideal for the efficient and highly-accu-rate heavy-duty machining and theexcellent surface qualities.

Depending on its size and complexi-ty, machining a blisk can take between60 and 80 hours, sometimes, even lon-ger. Every interruption to the executioncan cause an almost-completed part tobecome a reject. In such a case, the va-luable calendar time remaining untilthe planned delivery date, the machinehour costs and the expensive specialmaterial are all lost.

Consequently, not only highest ma-chining quality and excellent cuttingcapabilities are demanded from the ma-chine tool, but, as Herben Legl empha-

.A --

The high thermal, mechanical anddynamic flow loads in the jet engi-ne demand the highest-possibleproduction precision and surfacequality for the manufacturing ofthe complex structures of blisks.

sized: "A very decisive factor is the reli-ability of the controller!" Aerotech hasordered the machine with a CNC of theSinumerik 840D series. The controller,well-known for its extreme reliability,also offers many possibilities to betterutilize and further improve the produc-tivity of machine tools.

This begins already with the installa-tion of the pan programs generatedfrom the OpenMind, Exapt and Tebisprogramming systems. The DNC modu-le transfers them to the machine fromthe Motion Control Information Systemavailable for the Sinumerik CNC at acentrallocation. This type of integrationin the CAD-CAM manufacturing envi-ronment is very easy to use.

aerotec' june 2009 39

MANUFACTURINGSPECIAL

Ii

To increase the cutting capability,Aerotech uses CNC's Compcad com-pressor function and special commandsfor the roughing and finis hing in the5-axis simultaneous operation. Not on-Iy does the Compcad compressor bysmoothing the movement transitionsalready achieve a better utilization ofthe machine dynamies (with the conse-quent approximately 15% faster cuttingspeed), but also the tolerance cyde, to-gether with the CNC's dynamie com-mands, brings a further 15% improve-ment.

The long cutting times mean this sig-nificant improvement has alm ost acomplete direct effect on the overallproductivity - and so greatly improvesthe capa city and earning potential ofthe production.

"Another benefit for us was that theShopMill workshop user interface is al-so available for the Sinumerik control-ler. This allows us to utilize the manu-facturing precision of the machine, alsoin the jig construction or even morecomplex prismatie mounted parts, di-rectly from the drawing. ShopMill alsosupports many setup tasks very effec-tively", reported Karsten Riemer, thesection leader for the technology deve-lopment and machine acquisition, onceagain. And because ShopMill allowsprogramming and job preparation whilemachining is being performed, the com-pa ny gains a practiee-oriented program-ming workplace with each such equip-ped machine.

One of the tasks that the productionexperts at Aerotech performed to inves-

40 aerotee'june 2009

tigate the production accuracy of theAlzmetall GSI000/5T with the Sinume-

rik CNC involved manufacturing a ringwith drill pattern. The drilled holes we-re once set in the dassie manner with

fixed spindie position and workpiececontinuing to rota te segment-wise. Inanother workpiece, the drilled holeswere placed using a coordinate-cont-rolled approach to the drilling positions.The agreement of both procedures wasbetter than 1/100 millimeter, as was thecircularity of the ring manufacturedusing circular milling. Another proof ofthe high machine precision: after fourhours of intensive heavy-duty cutting

The zero offset in the Z-direction

compared with the cold machinewas lessthan 2 micrometers

under full load, the zero offset in theZ-direction compared with the cold ma-chine was less than 2 pm.

All tests and the very good experi-ence gained in the running productionconfirm that the GS1000/5T benefits

have by no means been fully utilized,quite the reverse, it obviously still hassome potential. This makes the machi-ne an ideal platform for the further de-velopment of the technologies for the5-axis simultaneous milling. Together,Aerotech Peissenberg, Alzmetall andthe automation partner Siemens ac-tively pursued this and also cooperatewith various institutes. For example, in

Thanks to its standard kinematics, themachine acquired tor the blisk produc-tion can also be used tor the se ries

production ot complex prismatic parts.

The controller dynamic commandsallowed Aerotech to increase the

overall productivity by approxi-mately 30 percent.

cooperation with the Aachen Fraunho-fer Institute for Production Technology(IPT), the potential of double splines forthe harmonie and the jerk-free reorien-tation of the tool for the 5-axis simulta-

neous milling was investigated. In par-tieular, harmonic speed transitions,even higher overall feed speeds andfurther improved surface quality can beattained at the transition between largeand small radiuses found in the bliskblades.

Because the Aachen institute has al-so acquired an Alzmetall GSI000/5T topursue the further development of mil-ling technologies, etc., Aerotech Peis-

senberg may be able to directlybenefit from the results of theresearch and developmentwork at IPT Aachen.

At Aerotech, the experiencegained from the production ofblisks, pylons and other jet en-gine components resulted in

the company very soon investing in asecond, identieally-equipped machine.As Manfred Zimmer. production mana-ger at Aerotech, explained: "This com-bination of machine and controller isnot only state-of-the-art technology,but it also provides all prerequisites forthe further development of our produc-tion technology and strategy. We canbenefit from the dose cooperation withboth Alzmetall and Siemens - both

have proved themselves to be commit-ted partners who also share the samelarge interest as us in pursuing the tech-nologieal innovation."

AloisPenzkofer+-