Checking reflective metal punches for position


In transport containers (trays), punches (tools made of metal or tool steel) are fed into a laser labeler for automatic processing and their orientation checked by a camera system. Because the punches are transported in different positions on the transport system, it is very important that the OK angles of the punches (0° or 180°) and NOK angles (punches in the wrong position or punches not present) be reported to the control. It is also required that the OK positions be clearly distinguished, since the tray needs to be rotated 180° for further processing if the angle is 180°. All other positions of the punch must be detected as an NOK position and lead to the ejection of the tray. It is very important that punches with different material properties be reliably detected. This is because the metal punches reflect the light very strongly and have varying colors and brightnesses. The background is sometimes lighter, sometimes darker. Thus, with respect to brightness, it stands out only slightly from the metal punches, i.e., this is a very low-contrast application. The two OK positions and the NOK orientations of the punches must be output as separate position signal via the digital outputs. The evaluation time should be less than 100 ms.


The LSIS 421i smart camera with all corresponding cables and mounting brackets is used. The homogeneous and strong illumination of this smart camera enables reliable evaluation. The reflective behavior of the machined ends of the metal punches is used to determine the orientation. Due to the very strong and homogeneous illumination of the smart camera, the reflections at the points of the punches can be uniquely and reliably evaluated. The smart camera performs the evaluation by means of BLOB attributes "area, height, length of the major and minor axes". Through a combination of these attributes, all other reflections and features, even if these may change, are clearly distinguished from one another and the 0° or 180° orientation of the punch clearly determined. By means of one BLOB tool for the 0° orientation and one for the 180° orientation, two independent signals are output for the orientation that is found to exist. Another BLOB tool for NOK "no punch in position" is also made available to the control for ejecting the tray. The evaluation time for all three evaluations together is just 85 ms.


  • Branch/Area

    Material Handling Robotic (feed)

  • Duty

    Orientation detection

  • Application

    Checking reflective metal punches for position