The requirement for high-quality production is not just evident within Mercedes-Benz – the end-users, in particular, have high expectations of the manufacturing quality of a Mercedes-Benz vehicle, no matter what model. This includes the need for a vehicle to be absolutely water-tight so water cannot enter through closed windows, doors and hatchbacks. Neither rainwater from a downpour, nor car wash cleaning water, nor water from high pressure cleaners is allowed to enter the vehicle interior. Elements that are not a challenge in contemporary series production must, however, be carefully monitored during the start-up production of a new car model. It takes a few weeks until a manufacturing process is 100 per cent trouble-free and error-free. It is only when all the components have the required size accuracy, all seals have the correct shore hardness and all employees have internalised all the production steps that the series production can run smoothly. The integration of additional control devices, batteries and wiring harnesses has dramatically changed the demands on quality control during the production start-up phase.
“New vehicle technologies, such as cars with a hybrid drive, require the rethinking of test processes for quality control. RFID technology has the potential to become the basis for future leakage test methods”, says Dr. Axel Maykuß.
New vehicle concepts require new tests
Automotive technology has become much more complex in recent years. The engineers in automotive development use every cavity in the vehicles to place batteries for hybrid drives, plus necessary additional wiring harnesses. Control units and further components are also used for advanced driver assistance systems, for example. Technological advances in automotive technology carry a definite disadvantage for leakage testing: conventional methods can no longer be applied. A novel solution is urgently needed, as otherwise vehicles will need to be completely disassembled after production in order to test water tightness at vulnerable points.
Passive RFID measures moisture
Together with its technology partner, the Mercedes-Benz plant in Bremen has developed a method based on passive RFID for measuring moisture in a project that was initiated some nine months ago. The new RFID labels are glued into the vehicles at the start of production. Following production and rain-proofing procedures, the capacity load can be determined using an RFID transponder to find out whether or not water has entered the vehicle. Tests have already been carried out on two production start-ups. The results give genuine hope that RFID may be the most viable future method for the leakage testing of vehicles. In 2016, Mercedes-Benz and its technology partners will continue to work on this innovative use of RFID.
Up to six labels detect water
The production tests at the Bremen plant are not just about testing functionality to collect data to support a possible roll-out, but also to determine the required number of labels needed per vehicle. Depending on the model, the number currently varies from four to 14 labels a vehicle. Apart from taking a commercial standpoint, it is also important to consider a sensible and feasible technological perspective. According to the findings of the first tests, the label placement, used in an average of six different positions, seems to optimise processes.
An automation revolution
To eliminate manual processes during leakage testing, the use of automated RFID is a revolutionary approach that currently has the best potential for successful implementation. After all, the use of RFID should allow Mercedes-Benz to fully automate their vehicle quality control. The degree of automation in quality control should be brought to a higher level so that the employees can concentrate on their real work analysing leakages. A review process will now be established to assist the staff in vehicle tightness analysis and to reduce the overall working hours by eliminating additional manual tasks.