Introduction of the customerThe past
Labels are applied on the product by the automatic pneumatic applicator. Each label contains logo, description and the serial number in the form of code 39, used to identify the part along its way through assembly line. Originally a stationary linear scanner was used to read this barcode. With a new project the end user raised new requierement - to online control the exact position of each label on the part and assure the constant printing.
Needs for change
The main goal was to replace the original stationary linear barcode scanner with a multifunction device, that meets following requirements:
- read of 1D and DataMatrix codes
- control of the label application accuracy
- control of the printing accuracy within the label
- communicate with PLC via RS-232
- small form factor, allowing to mount device into limited space
Solution
After deep analysis and testing in laboratory conditions the integrator Bartech, s.r.o. decided to use industrial camera Microscan Vision Mini. Customer liked especially very small size 26x46x54mm. Although this device is equipped by internal illumination, the external lighting source NerlLte HI-BRITE 45 was used to emphasize contrast on the surface of monochromatic part. The communication of Vision Mini was set up to emulate the former scanner which allowed smooth migration without necessity to change program in PLC in case of the current label. After serial trigger is sent from PLC, the camera reads the barcode and information is sent to PLC via RS232. By a different command the scanner starts alternative part of JOB, simultaneously with barcode reading, the accuracy of the label position on the part and printing position on the label is controlled.
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Project evaluation
The system including HW was implemented in 3 steps. Firstly the feasibility testing in the laboratory was performed. As soon as the specific HW was selected, the testing right on the assembly line was done. The result was good and the specification for the mounting and communication protocol with PLC was agreed. Lastly the final installation, activation of the system and setting of tresholds was done along with intentional mistakes to verify correctness of NON-OK parts detection. What contributions did the solution bring?
- Smooth replacement of the original device without necessity to re-program PLC
- Elimination of claims from EUP because of improperly applied label
- Elimination of claims from EUP because of printing errors
