Rampazzo - Automated EP

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Automatic Electropolishing (Vanessa Rampazzo - 15')
Speaker: Vanessa Rampazzo - Legnaro National Laboratories of INFN | Duration: 15 min.
Abstract
Electropolishing is an electrochemical process adopted in order to reduce the internal surface roughness. The process involves a special equilibrium between the reagents and the products, that creates a differential electrical resistance through the micrometric peaks and valleys of surface. This regime is detected collecting the current in function of voltage. Observing dinamically the changes of the characteristic curve during the process it’s possible to ensure the best electropolishing setting.

The Dynamic Control of the best electropolishing point int I-V Plane is done by an automatic program, that collects continuoulsy the voltage and current and calculates in real time the best setting. Roughness smoothing is accompanied by the removal of anomalies on the surface, as pitting and stratches. The automatic program is written in Labview language and works on a industrial computer, a PLC.

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  • The best polishing is obtained by keeping the voltage always in the plateau. But the polarization curve is not fixed and moves dynamically The numeric derivative of I versus V is automatically displayed and the working point is chosen as the minimum of the bath differential conductance dI/dV that corresponds to the point of maximum resistance of the viscous layer.
  • Faccio vedere il FP 2010
  • I parametri sono modificabili durante l’esecuzione del programma
  • Il programma scansiona da V in a V fin con passo Δ V Calcola la derivata prima Trova il minimo Si posiziona sulla tensione trovata per il minimo
  • Grafico con tempi e definizioni
  • Il programma è diviso in due parti: una in cui si impostano i parametri e una parte grafica per vedere l’andamento del processo in tempo reale
  • Rampazzo - Automated EP

    1. 1. Automated EP V. Rampazzo Development of the software based on the tuning of the differential electrolytic conductance for controlling the Electropolishing process ISTITUTO NAZIONALE DI FISICA NUCLEARE LABORATORI NAZIONALI DI LEGNARO
    2. 2. I-V polarization curve for EP The method consists in computer monitoring the I-V characteristic. Tuning of the EP process in the minimum of the differential conductivity dI/dV
    3. 3. Schema of the automated EP Digital Input-output Analogical signals VOLTAGE CONTROL REGIME The best working point of the I-V characteristic is searched and followed by during the whole EP process Electrolytic cell Voltage Supply PLC PC Automation Software
    4. 4. Field Point ® 2010 <ul><li>PLC: </li></ul><ul><ul><li>Industrial computer </li></ul></ul><ul><li>Programming language: </li></ul><ul><ul><li>Labview ® 8.5 by National Instruments ® </li></ul></ul><ul><li>I/O Modules: </li></ul><ul><ul><li>Writing and reading channels send and receive the data </li></ul></ul>Computer Interface ETHERNET o RS-232 Channels I/O
    5. 5. Automatic Software <ul><ul><li>Scan to detect the characteristic curve </li></ul></ul><ul><ul><li>Calculation of plateau </li></ul></ul><ul><ul><li>Following of minimum on derivative dI/dV </li></ul></ul>
    6. 6. Movie
    7. 7. Characteristic Curve Derivarive calculation
    8. 8. Following the minimum <ul><li>Short voltage scan around the minimum found </li></ul><ul><li>Recalculation of derivative dI/dV to follow the EP best point </li></ul>Minumum Range
    9. 9. Graphic Graphic plot of characteristic curve I-V Short range scan EP Derivative dI/dV
    10. 10. Manual set of EP working point <ul><li>Manual set </li></ul><ul><ul><li>it’s possible to put in another working point </li></ul></ul>
    11. 11. Manual set of EP working point
    12. 12. Adaptation of power supply parameters <ul><li>Setting of power supply parameter: </li></ul><ul><ul><li>Maximum Voltage </li></ul></ul><ul><ul><li>Maximum current </li></ul></ul><ul><ul><li>Voltage command range for voltage and current </li></ul></ul>
    13. 13. Conclusion <ul><li>The program finds and follows automatically the best EP point </li></ul><ul><li>All the parameters of process can be changed during the EP </li></ul>
    14. 14. Remote control <ul><li>The analog readings from the Power supply are converted to digital in a PLC and elaborated by the automation software </li></ul><ul><li>The digital output from the automation software are converted in voltage signals that drive the Power supply </li></ul>Remote interface
    15. 15. Thanks for attention!

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