Automated EP Automated EP V. Rampazzo 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
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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Automated EPAutomated EPV. RampazzoV. 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
I-V polarization curve for EP
The method consists in computer monitoring the I-V characteristic.
Tuning of the EP process in the minimum Tuning of the EP process in the minimum of the of the differential conductivity differential conductivity dI/dVdI/dV
0
2
4
6
8
10
12
dI/dV I
I [A]
0 1 2 3 4 5 6 V [V]
I/V
Schema of the automated Schema of the automated EPEP
Electrolytic cell Voltage
SupplyPLC
PC Automation Software
DigitalInput-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
Field PointField Point®®20102010
PLC: ◦ Industrial computer
Programming language:◦ Labview® 8.5 by
National Instruments®
I/O Modules:◦ Writing and reading
channels send and receive the data
Computer Interface
ETHERNET o RS-232
Channels I/O
Automatic SoftwareAutomatic Software
1. Scan to detect the characteristic curve
2. Calculation of plateau3. Following of minimum on derivative
dI/dV
MovieMovie
Characteristic CurveCharacteristic Curve
Derivarive
calculation
Following the minimumFollowing the minimum Short voltage scan around the minimum found
Recalculation of derivative dI/dV to follow the EP best point
Minumum Range
GraphicGraphic
Graphic plot of characteristic
curve I-V
Short range scan EP
Derivative dI/dV
Manual set of EP working Manual set of EP working pointpoint
Manual set◦it’s possible to put in
another working point
Manual set of EP working Manual set of EP working pointpoint
Adaptation of power supply Adaptation of power supply parametersparameters
Setting of power supply parameter: ◦Maximum Voltage◦Maximum current◦Voltage command range
for voltage and current
ConclusionConclusionThe program finds and follows
automatically the best EP point
All the parameters of process can be changed during the EP
Remote controlRemote control
The analog readings from the Power supply are converted to digital in a PLC and elaborated by the automation software
The digital output from the automation software are converted in voltage signals that drive the Power supply