Plug detection during vehicle painting


Located on the roof of a small van is a series of holes which, depending on the configuration, are fitted with or without plugs. Following CDP (cathodic dip painting; also referred to as cataphoresis), the vehicle is painted beige. The diameter of a hole is approximately 10 mm. Black plastic plugs are used to seal the holes. Both the holes as well as the plugs must be reliably detected as the vehicle bodies pass by. Because the van is available in two heights, it must be possible to check both heights with the sensor. Furthermore, the sensor must cover a large measurement range in order to compensate for tolerances in the process – for example, if the vehicle body is positioned at a slant on the skid transport system. Following the check, the sensor should output a digital signal to the PLC.


The LRS 36 light section sensor is used. It can cover a range up to 600 mm wide and can thereby also handle height differences on this order in the vehicle body. With the scanning rate of 100 Hz, it can reliably detect a 10 mm hole at traverse rates of up to 15 m/min. Testing showed that the light section sensor can reliably detect both the hole as well as the plug.


  • Branch/Area

    Automotive industry (painting)

  • Duty

    Quality control, Presence inspection

  • Application

    Plug detection during vehicle painting