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CaseStudy

The Theorem of flight

From CAD User Mechanical Magazine Vol 22 No 6 - JUNE/JULY 2009

The benefits of using lightweight visualisation formats to provide engineering staff with access to detailed design data are well recognised. One company maximising the value of this trend is GKN Aerospace Engineering Services - using Theorem's CATIA V5 to PTC's ProductView Windchill compliant adaptor to underpin the ability of its engineers to access and use visual product assembly data on their laptop PCs

Based in Weston-super-Mare, with subsidiary operations in Filton, Aldershot, the Isle of Wight and India, the 450-strong organisation is part of the global GKN Aerospace group - a first tier supplier of structures, components and engineering services with more than 30 manufacturing centres in Europe, the Americas and Australasia.

In common with other companies operating in the sector, GKN Aerospace Engineering Services has been at the leading edge of collaborative working, not only throughout its own organisation, but with its supply chain partners as well. "It means providing access to data on large or complex components and assemblies in an easily handled format," reports the company's Windchill Manager, Graham Taylor. "The vast majority of our designs are created in CATIA and result in assemblies that may contain several gigabytes of information. Clearly, most of our engineers simply do not require that level of detail for their own work. What's more, the hardware and software costs associated with providing CATIA licenses at every level throughout the organisation would be prohibitive - even before data security issues were taken into consideration. That's why we've adopted ProductView as our preferred data format for employees working outside the design area."

The selection of a lightweight visualisation format (ProductView) as opposed to the traditional method of exchanging CAD models or IGES or STEP files is part of a significant and fast accelerating trend. Traditional CAD data exchange methods for complex 3D designs have focused on full translation of all of the geometric content from one CAD format into another. Not only have the 'neutral' file types been striving to achieve this but there has also been significant successful development of direct CAD to CAD database translators. In some circumstances this has included not just 3D geometry but drawings as well.

In the closely collaborative environment of the aerospace supply chains this has resulted in huge amounts of data being transferred between business partners. It has worked but it has not been ideal. In many circumstances the recipient of OEM design data only needs a subset of the data to be able to undertake his design in context or design review activity and the large volume created by CAD to CAD or STEP translations of data has been an unwelcome side effect that has cost money and time.

Another undesirable effect for all concerned is that the translation of CAD to CAD or STEP models in collaborative working exposes a major risk to the security of intellectual property. Exchange of data in this way, in an environment where innovation is key to success, has the potential to transfer design intent and therefore unwittingly publish and distribute IP. Lightweight formats such as ProductView do not transfer the original design data and act almost like a filter that protects IP, and so not only have technical benefits but commercial benefits too.

Where the design data is to be used inhouse for an associated activity like the documentation of designs in technical publications for maintenance or purchasing there is no risk to IP - but lightweight formats bring other additional benefits. While CAD might be 'the master' the vast majority of associated downstream applications do not require all the detail held in the master. Technical publications might need to work with hidden line representations of design and perhaps exploded views of assemblies but all this is possible from lightweight subsets of the original CAD model. The same is true in purchasing or marketing, where realistic visualisation might be all that is required. The solution is to translate the design data into a format that is ideal for the purpose, and in this case GKN Aerospace selected ProductView.

The decision to output CATIA data into the ProductView format meant that the CATIA data would need to be translated and managed by Windchill, GKN's data management system. Following an exhaustive review of alternative methods, GKN selected Theorem Solutions' CATIA V5 to ProductView adaptor to handle the translation between two formats. Originally installed four years ago, the Theorem translator has been employed across a wide variety of projects for customers including Boeing, Bombardier, Allied Signal and Airbus.

"Furthermore, with up to 40 potential users of its ProductView output, it has been essential for the system to maintain a reliable flow of work," says Taylor. "In practice, it has been very much a case of the Theorem translator doing what it says on the pack. It simply acts as a 'black box' and has proved to be very robust in operation."

One of the reasons for the translator's reliability is its ability to deal with less than perfect geometry. Unlike many other data translators, it will flag queries and inconsistencies without stalling. This is particularly important with the kind of large assemblies found in the aerospace sector, where a minor glitch could potentially halt the whole data translation process. "We convert every iteration of a design project and this can comprise perhaps 200 or more individual data translations," Taylor continues.

Another strength of the Theorem translator is its ability to match CATIA in terms of dealing with mixed data. CATIA V5 will seamlessly recognise and handle V4 models within V5 assemblies. Similarly the Theorem translator recognises and translates CATIA V5 assemblies that include embedded V4 files or assemblies recognises eliminating the expense and complexity of two separate translators and contributing to a very easy workflow. "It all adds up to a high level of confidence in the system's ability to handle anything we throw at it, without any apparent memory leaks," notes Taylor. "So much so, that we now file some translated data 'unseen'." During the past four years, Taylor has also developed an excellent working relationship with Theorem's support team, reporting that they have always been very responsive to any problems he has raised.

"Overall, the Theorem package has reduced the challenge of accurately translating our CATIA data to a routine operation," he concludes. "It's a strong foundation on which to base our collaborative working and therefore an important factor in enabling us to maintain our organisation's competitive edge."www.theorem.co.uk

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