Delivering Differentiation

CNC

IN-DEPTH KNOWLEDGE UNDERPINS CUSTOMER SERVICES Delivering differentiation

Siemens is giving its customers the benefit of novel features and services alongside its CNC offerings in an effort to differentiate itself from competitors. Andrew Allcock reports

NC, like other computer technologies, Cis moving towards the commodity end of the scale, with feature or performance differentiation increasingly difficult. That is why, some years ago, Siemens decided to offer more, explains Dirk Rabeneck, senior account manager, aerospace industry. In the first instance, its target was those customers using advanced machine tools, such as the aerospace industry. The company’s VNCK CNC software plug-in for CAM systems is just one such result. VNCK – Virtual NC Kernel – integrates the CNC and CAM system to

Above, Tecnomatix software shown at EMO on an Index machine. Below, Huron ‘s KX200 at Delcam was optimised by Siemens

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Changing paradigm in

aerospace Airbus

With latest generation civil aircraft, provide accurate toolpath verification and highly promoted to end-user companies like Boeing’s 787 Dreamliner and cycle time calculation. The NC kernel is like Airbus, Boeing, Lockheed Martin, Mr Airbus’ A350 (picture, right) using literally the CNC operating system and it Rabeneck explains, adding: “They are really high proportions of composite possesses all knowledge about machine excited about it, but it took some time to materials (see also page 16), Mr dynamics and performance so that a CAM develop VNCK and then for CAM Rabeneck refers to a “changing system incorporating this is, to all intents companies to integrate it with their paradigm” in the aerospace and purposes, running the actual software.” Its appearance at EMO in the industry. Instead of starting out with machine. form of the Index/Tecnomatix large billets of aluminium and then CGTech’s verification program, demonstration is a mark of its increasing proceeding to machine over 90 per Vericut release 6, now incorporates prominence and move into more general cent away, the composite process is Siemens VNCK, Mr Rabeneck reveals, as machining areas. additive, with layers of composites does Unigraphics NX3, Tecnomatix (now built up over formers. So all these owned by Unigraphics) in its multi- PERFECT FINISH big projects require tape laying and spindle, multi-slide lathe programs, and VNCK is also an enabling technology in fibre placement machines instead of as will Dassault in Catia V5. Other CAM Siemens’ Mechatronic Support service, metalcutting machines. Happily, as firms are interested, too, he adds. which takes in the study and solution to Mr Rabeneck highlights, Siemens’ Tecnomatix’ VNCK integration was a surface finish problems, for example. “It is 840D can support these tasks as feature of the Index stand at last year’s very difficult to identify the root cause of, standard, notably using Curve Table EMO, in fact (see Machinery, October say, striation marks, on a surface and thus Interpolation, previously used to 2005, page 29, and picture this issue on to specify a solution to eradicate these. It support cam grinding. Ingersoll fibre page 23). could be down to tooling, the dynamics of placement machines at Spirit The benefits of VNCK to the user are the machine tool, the control or drive AeroSystems, Wichita, USA, are clear. UK aerospace companies, which system, or the resolution of the CAD fitted with 840D controls in support have been using imperfect simulation and system.” of 787 cockpit section manufacture. consequently experiencing machine Again the solution depends on the Mitsubishi in Japan, which is damage on high-value machines, are very VNCK file to provide a proper offline making 787 wings, is also using happy to have this new capability. And representation of the machine dynamics, three Forest Linè tape laying EADS, Augsburg, Germany, reports that but it is part of a ‘Wizard tool’ that also machines fitted with Siemens 840D overall machining time estimate takes in the complete archive file from an units. In another non-machine tool deviations of over 30 per cent – the wrong 840D control plus CNC program file. application, Airbus fuselage way – were being seen prior to the “With all this information, we can build a assembly is controlled by bringing incorporation of VNCK in simulation. virtual image of the workpiece and then two large MTores assembly rigs Machine tool builders, in support of investigate ‘separate branches’ of the holding the parts together – 18 axes configuring machining solutions for system. For example, we can see the effect are interpolated in this application. customers, also demand this level of of varying block preparation time or block “We can expect this composites certainty to support accurate quotations, interpolation time; the effect of the area to provide major Mr Rabeneck adds, instancing a recent dynamics of the machine tool; the developments,” asserts Mr conversation at EMO with a well-known geometry of the tool.” Rabeneck, “for example, simulation aerospace machine tool builder. From an end-user point of view, as Mr of the tape laying process – and If VNCK is so good, why haven’t we Rabeneck explains: “If you have installed a VNCK will help in that.” heard more about it? This feature has been machine with a value of £1 million or

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more, then you have a pretty strong after the event. One was for a machining incentive to understand from the centre where the natural harmonics of the beginning what sort of accuracy the upright column had to be changed, while machine will give you – both static and in another example a crankshaft turning dynamic. And you would also like to know set-up was experiencing resonance the productivity of your machining centre, because the natural harmonic of the chuck which is heavily influenced by the ‘jerk clamp was the same as the crankshaft. A capability [rate of change of acceleration]. before-the-event analysis would have You’d like to know servo-gain [system prevented the problems in the first place. stiffness/responsiveness], the following error [difference between where the RIGHT FROM SCRATCH control says an axis is and where it actually French machine tool builder Huron is at a given point in time] and on quality, made use of the Mechatronic Support you would like to know what deviations service on its KX200, 5-axis high-speed might occur in a circularity test. machine, one of which was installed at “In the past, you placed an order and Delcam’s Birmingham in-house you got a machine and maybe were machining facility just a few month ago. unhappy with its performance. Now with The Siemens 840D digital CNC system is the Mechatronics Support service it is the preferred control for the Huron possible to simulate the entire KX200, chiefly because Huron and Dirk Rabeneck recomends those spending performance of the machine, by building a Siemens collaborated closely on the large sums on their machine tools ask for a finite element model of the machine – mechanical design of the machine. virtual analysis – “why not?” which any university can do, of course, but Mechatronic Support from Siemens what Siemens has is a very good allowed Huron to overcome some As Mr Rabeneck also points out, end- understanding of the dynamics of our resonance difficulties with the KX200 and users in the aerospace industry, in drives and control systems and so can maximise the potential for the machine’s particular, have an interest in knowing simulate the entire system performance design. Rapid traverse rates in the two where the so-called ‘sweet spots’ are on before the machine is built, and can advise primary axes have been optimised at their large machines – those areas where machine tool builders what they should do 40 m/min, exceptionally fast for such a chatter-free machining can be assured. “It to address any issues. large, simultaneous 5-axis machine – the would be very helpful if machines were “If I was a customer placing a KX200 has travels of 3,300 by 2,300 by delivered with the ‘sweet spots’ identified.” £1 million order, I would ask for a virtual 1,000 mm. Siemens also aided the A thorough analysis using Siemens’ analysis first – why not?” potential for speeds of 30 rpm in the two technology would reveal them. And he offers two examples from the rotary axes by developing the use of high- Apart from its VNCK and the UK. Two machine tool OEMs came to performance torque motors built into the Mechatronic Service, other Siemens Siemens when they discovered problems machine head. services/products include a machine tool network product which allows machine tool condition monitoring, such that a service action is flagged when a threshold Volumetric accuracy promotion is exceeded for, say, current drawn by the spindle. Siemens is now proactively marketing volumetric error compensation, SinVCS. Siemens subsidiary EPS is already The underlying algorithm was developed at Huddersfield University (see providing Internet-based, remote Machinery, 3 September 2004, page 14). As an option, thermal compensation management of large company machine software can be used in parallel to improve this and both can be integrated within installations using such technology. A the 840D without any external hardware. All companies involved with the Joint Daimler Benz engine factory, near Strike Fighter project, such as BAE Systems, Samlesbury (see Machinery, Cologne, in Germany, is a user, while a October 2005, page 20) are considered to be candidates, due to the stringent project is underway with US motorcycle accuracy requirements that underpin both JSF’s stealth characteristics and the manufacturer Harley-Davidson, and use of standard in-service replacement parts. The first customer in the UK, discussions are also underway in the UK indeed the first real test of the system in industry, is GKN Aerospace, Isle of with another large manufacturer. I Wight, where the volumetric accuracy figure for a large Henri Linè machine has been slashed by 90 per cent even before the use of any thermal compensation. ℀ Enter 100 at www.machinery.co.uk/enquiry