The Volkswagen plant in Zwickau has a history of more than one hundred years in car manufacturing. The Zwickau vehicle plant is still home to the traditional production areas of body construction, paint shop and final vehicle assembly, but since 2020 only electric cars have been manufactured there. The approximately 10 700 employees at this Volkswagen site now produce fully electric vehicles such as the VW ID.3, ID.4 and ID.5, the Audi Q4 e-tron and the Seat Cupra Born, as well as the bodies for the Lamborghini Urus and the Bentley Bantayga. The conversion of the plant into a multi-brand location for eMobility and the expansion of the variety of models produced demands more efficient work processes in the department of measurement technician Marc Gündel. „Contrary to popular opinion, it has become rather more involved,“ Gündel explains. „Due to the reduction of the vertical range of manufacture in the factory, much more complex assemblies are supplied today, which leads to a massively increased support effort. To cope with the extra work, we need the right measurement systems.“ In 2022, VW Zwickau acquired the DPA Industrial photogrammetry system from Hexagon with its 50.6MP sensor. These measurement systems are equipped with only a single portable camera unit. Together with the C1 camera unit and the DPA Pilot software platform, the system guarantees a complete high-productivity workflow, from signalling and recording to calculation and reporting, and with minimal training.
Inspections in 15 Minutes
„We use DPA Industrial as an inspection system for our fixtures,“ explains Gündel. Before the system is used for the first time, all geometry fixtures are checked for dimensional accuracy with a laser tracker or measuring arm and corrected if necessary. Afterwards, a data recording is made with the system. For this, special adaptors are inserted into the reference bores and targets applied to the fixture. All relevant fixing points are signaled with uncoded marks. A kind of virtual template is created with the data generated during the measurement with the DPA system. „We simply take a few pictures with the DPA Industrial and can make a quick statement as to whether the fixture is ok or not,“ says Gündel. A quick check is important because many of the 300 to 400 geometric fixtures are integrated in protective circuits that must be interrupted for the check, which in turn means downtime in production. „That means the times we can use to check the fixtures are relatively limited. During normal working hours, these are the breaks. With the DPA Industrial, we only need 15 minutes for the inspection – a lunch break is enough to get a clear statement about a fixture.“
Check of 180 Part Carriers
„We also use the DPA Industrial to check our skids,“ adds Gündel. Skids are part carriers that are used to bring the individual components to the processing station. To do this, the components are placed on the skids by robots, which then move them to the production line. At the VW plant in Zwickau, there are six identical skids for each assembly; in total, that makes 180 part carriers for all the vehicle models produced there. „We have to check the skids in exactly the same position as they remain in the production line. For this we have a special measuring table on which we can quickly perform checks.“ As with the fixtures, the skids are photogrammetrically recorded for this purpose before the first use. The resulting point cloud is used to create a virtual template that is later used for quick checking. To keep the automated production lines running, the part carriers must be available at all times. „If a problem is reported to us with one of the skids, we need to be able to react immediately,“ explains Gündel. „If, for example, a crash happens in the plant, the whole system comes to a stop, which means we have production downtime. That’s why time is a critical factor: with the DPA, we can carry out a quick check and determine in no time what damage has been done to the skid. With other measuring systems, this inspection takes three to four times longer.“
Add-on for Handheld Scanner
The most important application for the DPA Industrial at VW Zwickau is currently its use as an add-on for a handheld scanner. „We signal distinctive alignment points and holes on the car body with targets, record them photogrammetrically with the DPA Industrial and export the captured points from DPA Pilot. We then import these points into the scanner software. Now we can easily scan in alignment with the car body using the handheld scanner. And that’s despite the fact that we can’t fix the body and it’s only on a loose trolley,“ explains Gündel. The fact that they have managed to get these two independent systems to talk to each other saves Gündel’s team the time-consuming task of sticking targets on the car body – „and the subsequent removal of the measuring marks,“ Gündel adds. The DPA Industrial has a decisive advantage when compared to the photogrammetry system offered with the scanner: „The DPA Industrial can also measure coded measuring marks and adaptors. This means that the DPA offers us many more possibilities for later applications.“