Innovative solution for moisture sensing in automobile production
05 June 2017
Working in close co-operation with a leading car manufacturer, Turck has designed a fully automated solution for moisture sensing based on RFID.
In the automotive industry, before a new car leaves production, it is checked for water ingress at multiple points throughout the bodywork. For this process it is exposed to different situations in a sprinkler chamber that simulates rain, water splashes and car wash facilities. Next, moisture checks are carried out to determine any ingress but as these are manual inspection methods they cannot offer total, error-free, assurance. Quite commonly, moisture collects in areas that are impossible to see.
Together with its partners Smartrac & Vilant, Turck offers one of the world’s first system solution for fully automated moisture sensing. The system is based on UHF RFID technology and detects all moisture ingress in car bodies without the need for any manual intervention.
Radio-Frequency Identification (RFID) uses radio waves to read and capture information stored on a tag attached to an object. A tag can be read from up to a metre away using a two-way radio transmitter-receiver called an interrogator or reader that emits a signal to the tag using an antenna. The tag responds with the information written in its memory bank. The interrogator will then transmit the read results to an RFID computer programme. This system offers 100 percent detection of faulty vehicles, maintaining brand confidence and eliminating the need for costly aftercare.
In order to detect all moisture, the car body is fitted with tags at convenient stages throughout production. These tags react to humidity, even in concealed places. Before the car is driven into the rain spray chamber as part of the final inspection, it goes through an RFID gate which registers all the RFID tags. After the spray process, the car goes through a second RFID gate at the exit which reads all the RFID tags again. If humidity has penetrated at any point the system detects a discrepancy between both read operations and sends an appropriate fault message to the Manufacturing Execution System (MES) of the user. Car bodies that are affected can thus be removed directly and investigated.
As part of its customer support policy and in close collaboration with an automobile manufacturer, Turck has drawn up a requirements profile for the system for moisture testing. For every installation, only once the initial test phase is successfully completed on-site and the test feasibility determined in an actual application do Turck hand over the turnkey solution.
The passive UHF-RFID sensor tags can be stuck directly on metal and later read in positions that are difficult to access due to the surrounding structure of the vehicle. Thanks to this capability and their compact format of 21.5 x 73mm, the self-adhesive tags can be mounted, without any problems, on many points in the car body. For areas that are extremely difficult to access, Turck have devised special tags with extension strips that will register moisture in the smallest cavities.
If the tag detects humidity, it reacts with a change in impedance, which is registered within the RFID read process. RFID evaluation software allows the affected areas to be localised precisely by means of the collected data.
Being a passive RFID sensor tag it does not require a power supply and can remain in the car for its entire lifetime so that it can be read again at any time. The tag draws the required energy from a handheld device or the read write heads of the gates.
The elimination of faults, particularly in manual operations, and the continuing challenge to achieve zero-defect production, is paramount in the automotive industry. The introduction of a fully automated solution for moisture sensing and the increased level of quality it affords benefits customers and increases confidence in the brand.
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