Detecting coating defects in real time
Ideas for optimized production
Kübler Essig Maschinenbau GmbH offers solutions for this purpose, with which the quality of the products can be monitored and documented directly in the manufacturing process. The company, based in Ebhausen in the district of Calw, Germany, sees itself as a technology partner for the redesign and optimization of manufacturing processes. In this way, new ideas for mechanical and electrotechnical design, for automation and for the integration of measuring and testing equipment are continuously being developed in the medium-sized company.
Seamless documentation
"Companies increasingly have a need for networking automation and data technology," says Joachim Kübler, Managing Director of Kübler Essig. "In this context, seamless documentation as well as the visualization of production data is of immense importance." Under this premise, an innovative measuring table was also developed, which can be used to monitor the coating thickness of aluminum rims without contact and with robot support.
"By integrating non-contact automated coating thickness measurement directly into the production process, material costs as well as personnel costs for quality assurance can be saved and higher productivity can be achieved through less scrap," says Kübler. "Above all, however, with the robot measurement application we provide users with transparently prepared measurement data and enable seamless documentation."
Non-contact measurement through thermal coating testing
The core of the measuring table is the coatmaster, a non-contact measuring system from Winterthur Instruments, which detects the coating thickness using the thermal coating testing method: After a short pulse-like heating of the coating by a few degrees Celsius by a light source, an infrared detector records the surface temperature profile. Since the temperature decays with a characteristic dynamic - depending on the coating thickness and thermal properties of the coating - the system can determine the coating thickness from this. The sensor measures the thickness of the applied coating on the aluminum rim at 16 different measuring points, with the rim rotating over a rotary indexing table. A Denso robot therefore cycle-tracks the measuring device to the measuring point to be detected. The measurement data acquired by the coatmaster is recorded by a Siemens S7 PLC and logged on a PC.
Saving PLC data as CSV files
"For this purpose, we needed a system with which the data from the S7 could not only be recorded, but also documented and visualized on a PC," explains Joachim Kübler. The data logger was to store the measured values in the form of CSV files - due to their simplicity, files in the Excel format can be exchanged between any systems and can also be read and processed directly with Excel. Kübler Essig therefore chose the Accon-EasyLog software from Delta Logic: the data logger with intuitive user guidance enables data to be read out quickly and conveniently, as well as stored from all currently available Siemens controllers. The logging of data can be either time or process controlled and can be linked to various conditions. A special feature of the solution is that the Siemens TIA project format *.ap15 (TIA module) is also supported. This means that all PLC data can be captured without any loss of speed; an online symbol upload for the S7-1200/S7-1500 is also possible via the configuration interface.
Easy-to-operate datalogger
The operation of the software is simple and intuitive: The parameterization of the datalogger is guided by an assistant. In addition to "classic" I/O values, text can also be output. Furthermore, it is possible to use "virtual variables", which are calculated from the values of the controller. Various functionalities additionally simplify the application: For example, the Accon-EasyLog parameterization can be easily exported and imported and can thus be easily copied from one computer to another. When the CSV files are opened in Excel - and thus locked - the incoming data is buffered by the PLC. In addition, Accon-EasyLog is able to record both the current and the previous data set - this can be helpful when changing products.
Further processing of data in Excel
The currently read process data are directly displayed and graphically represented in Accon-EasyLog. An unlimited number of measured values can be recorded and viewed at any time. The data transmitted by the PLC is also saved as a CSV file and can then be displayed and further processed in the spreadsheet on the PC, for example. Alternatively or as a supplement to CSV logging, the data can also be saved in an SQL database. "By recording and visualizing the coating thickness measurement results in real time, the machine operator can ensure the quality of the applied coating directly in the process and thus react to deviations as quickly as possible," emphasizes Joachim Kübler.
Kübler Essig has thus implemented a "dashboard" via Excel: Here, the measured values are displayed in detail - with a time stamp - in tabular form and compared with the permitted maximum and minimum values in the form of a curve. Deviations can thus be detected very quickly. At the same time, the dashboard displays the number of overshoots and undershoots in the form of a pie chart. Another dashboard compares several measurements with each other, so that trends over a longer period of time can also be detected.
Easy to use, reliable in recording
Joachim Kübler's conclusion is correspondingly positive: "As a software tool for logging, documenting and visualizing data, the EasyLog software program is highly recommended. In addition to its ease of use, it always reliably recorded the measurement data." Thanks also to the datalogger, users of the coating thickness measurement system from Kübler Essig can detect coating errors reliably and quickly, and easily document the measurement parameters obtained.
Monitor and store your PLC process data for quality control as CSV file or in an SQL database with the modular datalogger ACCON EasyLog. It supports S7 Classic and TIA Portal project formats. The graphical representation of your data is also possible via the corresponding module.