Free up your legacy data

Transferring CAD data between different systems and getting at legacy data can be a costly, time consuming problem for many manufacturing companies. Dean Palmer looks at some software that eases the burden on suppliers

Transferring CAD data between different systems and getting at legacy data can be a costly, time consuming problem for many manufacturing companies. Dean Palmer looks at some software that eases the burden on suppliers

Arvin Meritor is a global Tier One supplier to major automotive manufacturers. It has more than 27,000 employees world-wide and designs and manufactures a wide range of sub-assemblies for its customers including axles, wheels, suspension systems, sunroofs and clutches.

Designing and engineering sub-assemblies for auto OEMs means that the company has to be able to accept and deliver CAD data in exactly the same format as its customer requires. In practice, this usually means that the company has to maintain a range of software licences of those CAD systems used by each OEM that it supplies, or would like to supply.

Aside from higher software licence costs, the real problem for suppliers like Arvin Meritor is that they want to have complete freedom to design in whichever CAD/CAM software they think is the most appropriate for the job. The OEM only cares about getting the right results and being able to use them – what goes on behind the scenes is of little concern.

The transfer of data from an OEMs native CAD system to the one the supplier wants to use internally is rarely ever straightforward. Companies may attempt to use an intermediary file format such as IGES or STEP, but these rarely go smoothly largely because different systems treat IGES – which was originally conceived as a 2D format – in very different ways when it comes to defining solid 3D geometry. Effective transfer of data between systems has proved so elusive that some OEMs have even put in place policies that insist on the use of the same CAD software throughout the engineering supply chain.

So, although these policies are beneficial to the OEM, there are suppliers out there today that are being crippled by the data transfer costs associated with such systems and procedures. Arvin Meritor has addressed this problem by implementing CADfix from ITI Transcendata.

Arvin Meritor’s plant in Stirchley, Birmingham is the home of the company’s Access Control Systems business. This looks after the systems that allow legal entry to automobiles: doors, locks, safety devices, actuators and latches. John Osman, application engineer at Stirchley, told Eureka: “Our designs must be unobtrusive, essentially invisible while at the same time be extremely secure. Most modern access control systems still rely on some form of mechanical latch controlled by some form of actuator and this is a potential point of weakness if someone is determined to break into the car. Our job is to design in as much security as possible within a constrained environment.”

Until a couple of years ago, the division performed all its design work using CADDS 5 and had to work around the need to accept and deliver other CAD formats as and when such needs arose. Then, partly due to pressure from some OEMs, and partly because the company feared that CADDS 5 was perhaps destined for little or no ongoing development by PTC, the firm decided to revisit its corporate CAD policy.

The company’s manufactured parts fall into two broad categories: those businesses that manufactured parts and assemblies for heavy commercial vehicles; and those that focus on light vehicles such as the Access Controls division. The light vehicles group decided to standardise on Catia (from IBM Dassault) as its core CAD/CAM system. But because of the CAD data translation issues, this was not enough on its own.

Osman continued: “For our requirements at the time, we were convinced that Catia could provide us with the best overall mix of functionality and that it would do a great job as our standard 3D modelling platform. But we could not ignore the pressure from the OEMs for direct interoperability so we have ended up with a mix of systems including Catia 4 and 5, Ideas (from SDRC, now EDS) and our existing CADDS 5. In effect, we’ve gone from a single CAD system two years ago to using at least four now, more if you take into account our CAM and CAE tools.”

The problem for Osman and his colleagues was re-using the legacy data from the CADDS 5 system. Initially, the only medium available for data transfer was IGES but it quickly became clear that this method posed more problems than it solved. Osman explained: “It is vital for us to be able to access our legacy data. This is the only way we could ensure that the work we have undertaken in the past on both historical and ongoing projects would not be wasted. But using IGES to move the data from CADDS 5 to Catia turned out to be a long, drawn-out process.”

According to Osman, Catia treats IGES as collections of surfaces rather than as true solid geometry. In turn, this means that data transfer must begin with extensive preparatory work in CADDS 5, turning the surfaces and exporting these trimmed surfaces to be re-combined into solids in Catia. Each part could account for up to 30 minutes of preparation time and with up to 40 parts in a typical latch/actuator assembly, this was causing bottlenecks in the design office.

To solve the problem, the company bought CADfix, deployed on a floating licence system so that it is available to all CAD/CAM/CAE system users. “We knew that CADfix provided a reliable intermediary for transferring data via IGES, so we initially took it on board to import and export IGES in such a way that the preparation work in CADDS 5 would no longer be needed. We have since invested in the native Catia translators, but even via the IGES route we have seen massive improvements with CADfix,” said Osman.

Instead of 30 minutes preparation time for each assembly component, parts can now be transferred from CADDS 5 to Catia in around five minutes. And according to the company, this alone has provided a clear business benefit as a full assembly takes no more than a couple of hours to produce instead of days.

But CADfix is also enabling the company to share live engineering data between departments. STL files, for example, can be exported directly from CADfix for use in the firm’s dynamic analysis software, Adams. And the FEA team at the company also regularly make use of CADfix’s de-featuring functionality, which removes small details that have been included by the designer but are not significant from an engineering viewpoint and will cause disproportionate problems when it comes to meshing for analysis.

Osman said that, in total, some 70% of the components his team produces are now processed in CADfix at some point in the design cycle.

Tom Shelley

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