Delcam software helps keep Nissan on top


The Nissan Micra Car
A typical press tool section at Nissan after repair with the Delcam software Using inserts to replace damaged areas extends the life of the tooling

Over the past few years, Nissan’s site in Sunderland, UK, has become renowned internationally as the most productive car plant in Europe. Steve Easter from Press Engineering and technicians in the Press Die Maintenance section use Delcam’s Power Solution software as part of their contribution to this proud record.
  
Currently all press tools used in Sunderland are supplied from Japan. It would clearly be too expensive to return them to Japan for design modifications so an NC facility was set up in Sunderland based around an Okuma MCR B II, five-axis machine with a 5 metres by 2 metres bed using Delcam software. Despite its size, the Okuma gives an incredible 2 micron accuracy across the length of the bed.

The original investment justification, when the unit was first established, was to reduce new model introduction time by completing detailed tool changes in the UK rather than Japan and to allow more efficient repair of trimming tools. Previously, design changes and damaged cutting surfaces on the tools were built up with weld and then ground into shape by hand. "Now we have the technology to fully complete reverse engineering applications,” commented Mr. Easter. "This makes it much easier to maintain the necessary accuracy we require.”

Now a profile is digitised from the trim line on the press tool by fitting a Renishaw probe onto the Okuma machine. The captured data is then used in a combination of Delcam’s CopyCAD reverse engineering software and the PowerSHAPE hybrid modeller to recreate the trimming edges of that tool. A model of the trim edges is then passed to the PowerMILL CAM system for machining data to be generated for their recreation on the Okuma NC machine.

Initially with trim tools, the new process was used simply to duplicate the manual operation in carrying out local repairs to each damaged area. More recently, it has been expanded to cover machining of all the welded sections and replacing the complete trimming edge. "Replacing the whole edge doesn’t take that much more time,” claimed Mr. Easter. "Plus it gives a much better result with a longer time between subsequent repairs.”

The next application to be developed was to replace sections in draw tools, especially where laser welding is used to join sheets of different grades of metal together. These areas wear more quickly because of the effects of the laser weld so there is a need to replace them with harder material to extend the overall lifetime of the tool. Again, surface data from the affected area is collected with the Renishaw probe. The replacement section is modelled with CopyCAD and PowerSHAPE and then machined on the Okuma machine with toolpaths generated in PowerMILL.

The establishment of a new database developed by technicians, containing PowerSHAPE models of the various press tools as they are repaired, has given extra benefits in Nissan’s quality control process. If any inaccuracies are found in panels from a particular die set, the tool can be scanned and the results checked against the database. It is then both quick and easy to see if the problem is with the die surface or whether it is from another cause.

When asked about his choice of software, Mr. Easter said, "The main reason for choosing Delcam was that I could get all three elements of the system – reverse engineering, modelling and machining – from a single source. Other potential suppliers were offering a mixture of programs from different developers, which I thought could cause compatibility problems.”

"As well as being better integrated, the Delcam systems were also user friendly,” he added. "The layout seemed to be very logical and this has proved to be the case. Even though we are only part-time users, we still get the excellent results we need.”