1. Process energy sources for the electrochemical machining process
and hybrid machining with ECM
Dr.-Ing. Dipl.-Phys. Hans-Peter Schulze 1
Dipl.-Ing. M. Läuter1
Prof. Dr.-Ing. G. Wollenberg1
Dr.-Ing. Maria Zybura-Skrabalak2
Dr.-Ing. Anjali K De Silva3
1 Otto-von-Guericke University Magdeburg
Institute for Fundamental Electrical Engineering and EMC
2 IOS Krakow
3 Glasgow Caledonian University
Department of Engineering
Title
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2. 1. Introduction and motivation
Contents
1. Introduction and motivation
2. Process energy sources and their characteristics
3. Application of EC-Process energy sources
4. Summary and trends
Contents
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3. Process combinations give possibility to reach the better
results than in separate processes by their disadvantages
elimination.
Energy sources are the connecting elements
which ensure an acceptable compromise
of the working processes.
Introduction
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4. Surface layer properties
EC-process
Surface layer properties
Machining process
Finishing and polishing
Micro-machining
Hybrid machining process
EDC machining
Micro-machining
Importend facts
Introduction
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5. Surface layer properties
EC-process
Surface layer properties
Life time of workpiece
(tool)
Chemical, thermal and corrosion wear
Thermal and mechanical shock resistance
Chemical constitution
Distribution of micro-hardness and stress
Defects in surface layer
Roughness parameters
Surface layer properties
Introduction
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6. EC-process Machining process Finishing and polishing Micro-machining
Gap voltage (gap die)
Electrode feed rate
Kind of used current or voltage pulse
Current density
Kind of electrolyte properties
Hydrogen concentration
Potential drops in layers adjacent to electrodes
Process energy source
parameters
Control for electrochemical
dissolution state:
active,
passive and
trans-passive state
Machining process
Introduction
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7. Hybrid machining process
EC-process
Hybrid machining process
EDC machining
Micro-machining
High precision and high removal rate
Depassivation for passivated electrolyte
Remove of thermal-affected layers (zones) - EDM
High aspects by drilling
Small electrode wear
Process energy source
parameters
Hybrid machining process
Introduction
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8. Process energy sources
EDM
ECM
* Dielectrical liquid
* Ignition stage Discharge
* Non-linear characteristic u-i
* Thermo-hydraulic removal
* Removal and electrode wear
* Inadequate discharges
* Thermal-affected layers
* Electrolyte liquid
* Anodic dissolution
* Linear characteristic u-i
* Thermal problem for fluid
* Removal and not electrode wear
* Problem with discharges and short circuits
* Passivation
Combined machining
Hybrid machining process
Introduction
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9. 1. Introduction and motivation
Contents
1. Introduction and motivation
2. Process energy sources and their characteristics
3. Application of EC-Process energy sources
4. Summary and trends
Contents
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10. DC-Sources Pulsed DC- Sources Normal Normal Mechanical oscillation
Ultrasonic
vibration
Ultrasonic
vibration
Ultra-short pulses
< 10 µs
Assisting
process
Short pulses
< 1 ms
Long pulses
> 1 ms
Assisting
process
Global
Energy sources
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11. DC-Sources Simple built up High working current
Low parameter flexibility
High productivity
Voltage
supply
Current
supply
Limitation of the
application
Minimum electrode wear
Gap die
control
Good value in
roughness
Voltage depended
gap die
Controlled current
density
No thermal-affected
layers
Small processing
precision
DC sources
Energy sources
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12. Pulsed DC- Sources Modular built up Higher working current
High parameter
flexibility
High productivity
Voltage
supply
Current
supply
Pulse duration
Minimum electrode wear
Current
magnitude
Pulse
shaping
Gap die
control
Pulse pause
Good roughness
Mean of the
current density
Pulse current density
No thermal-affected
layer
Better processing
precision
Pulsed DC sources
Energy sources
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13. Bipolar Pulsed DC- Sources Depassivation Normal anodic
Bipulse -cathodic
Ultrasonic
vibration
Depassivation
Ultra-short pulses
< 10 µs
Short pulses
< 1 ms
Assisting
process
Short pulses
< 1 ms
Ultra-short pulses
< 10 µs
Long pulses
> 1 ms
Global (2)
Energy sources
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14. Bipolar Pulsed DC- Sources Modular built up Pulse duration
High parameter
flexibility
Transition time
cathodic
anodic
Current
magnitude
cathodic
Voltage
supply
Current
supply
Pulse duration
Current
magnitude
Pulse
shaping
Gap die
control
Pulse pause
Energy of
negativ pulse
Pulse current density
Mean of the
current density
Better processing
precision
Pulsed DC sources
Energy sources
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15. Hybrid machining (EDM-ECM)
time-parallel processes
ECM
linear characteristic
Main process
assisting process
EDM
non-linear characteristic
Adjustment of
pulse parameter
Basic structure
of the energy source
- non-linear-
Pulse energy source
Process
optimization
Hybrid machining
Energy sources
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16. EDM ECM itotal Combined machining i i-u-characteristic breakdown inbv
OP2
edm
ecm
breakdown in
liquid
lim
itotal
i-u-characteristic
of energy source
OP3
Process Energy Sources Characteristics
Energy sources
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17. EDM ECM Combined machining Pure ECM Hybrid ECM-EDM Pure EDM20 40 60 80 5 10 15
Current in A
Voltage in V
Process Energy Sources Characteristics
Energy sources
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18. „ECDM, a new method for trueing and
dressing of metal-bonded diamond grinding
tools“
[Schöpf, M., Annals of the CIRP
Vol. 50/1/2001
Contents
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19. Process analysis Pulse parameters
Heating control
of electrolyte
Analysis of
pre-discharge
effects
Short
circuit
Pulse
parameters
Gap width control
- feed rate -
Flushing
control
Process control system
Energy sources
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20. 1. Introduction and motivation
Contents
1. Introduction and motivation
2. Process energy sources and their characteristics
3. Application of EC-Process energy sources
4. Summary and trends
Contents
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21. EC-Grinding
* gap die is function of abrasive grains and binding agent
< EC as additional removal process
direction in workpiece (anodic)
< EC as process for sharpenning of grinding disk
direction in grinding-tool (disk anodic)
< EC dressing
> Grinding as depassivation process
<
DC source
Pulsed dc sources
voltage supply
Short pulses
>
Pulsed dc sources
voltage supply
Long pulses
EC-Grinding
Hybrid applications
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22. EC machining on hard alloys (WC-Co)
* depassivation with bipolar pulsed dc source
* different remove of WC grain and Co binding agent
WC releasing Badness of surface
# For WEDM the EC process is to eliminate
ED sources - AC supply *
DC source
Pulsed dc sources
voltage supply
Short pulses #
Pulsed dc sources
voltage ac supply
Pulsed dc sources
voltage ac supply
Ultra short pulses
ED process source
Hard alloys
Applications
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23. EC-Deburring Simple machine and energy source complex machine
* fix electrode arrangement
* different gap die - burr -
* gap voltage control (big gap die)
Process
safety
Gap control
complex
Simple machine
and energy source
DC source
Pulsed dc sources
voltage supply
Long pulses
complex machine
and energy source
Pulsed dc sources
voltage supply
Short pulses
Process
safety
Gap control
mutablier
EC-Deburring
Applications
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24. High flexibility of the
ECM-USM
* Time-parallel processes for better surface quality
* Control of flushing in the working gap
< Additional powder for smoothing ! (influence of ECM)
* Synchronisation of both processes
DC source
Pulsed dc sources
voltage supply
Short pulses
High flexibility of the
process control
Smaller roughness
(comparison in next transparency)
ECM-USM
Hybrid applications
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25. Roughness Ra ~1,3µm ~1,2µm ~0,8µm ECM with constant current
ECM with pulse current
ECM supported by Ultrasonic machining
DC source
Pulsed dc sources
DC source
Pulsed dc sources
[nach Ruszaj, Zybura-Skrabalak,...
ISEM XIII Bilbao 2001]
Ultrasonic machining
Hybrid applications
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26. source with non-linear
Main process
Working liquid
Assisting process
EDM
ECM
Process energy
source with non-linear
u-i-characteristic
Basic energy sources
of the EDM
Dielectric liquid
removal rate
surface layer
ECM
EDM
Electrolyte liquid
removal rate
depassivation
EDM
Dielectric liquid
ECM
removal rate
with low conduction
passivation
ECM
EDM
passivating layer
depassivation
removal rate
Important factor by EC-ED-combination is passivation !
Structuring
Thermal-affected
layers
Smoothing
High speed
High speed
ECM-EDM
Hybrid applications
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27. 1. Introduction and motivation
Contents
1. Introduction and motivation
2. Process energy sources and their characteristics
3. Application of EC-Process energy sources
4. Summary and trends
Contents
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28. Structure of EC energy sources is simpler thanED energy sources
Summary
Structure of EC energy sources is simpler thanED energy sources
of the linear u-i-characteristic
Modern EC energy sources have a modular structure and are pulsed that
to improve the process accuracy in the case of high removal rate and big
machining surfaces,
to achieve high removal rate and high accuracy for micro machining
to make possible a combination with other electric processes,
to achieve a higher flexibility in applications.
With modular pulse energy sources can be reached a flexible process control
for ECM and their hybrid processes
Summary and trends
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29. ED process energy sources are the base for modern EC generators
Trends
ED process energy sources are the base for modern EC generators
Pulse Electro-Chemical Machining (PECM) is the precondition for further
process combinations, also in connection with non-electrical processing
PECM is very important for micromachining with smoothing surfaces
PECM is very important for machining in nanometer areas
„Older“ hybrid machining processes are useable for new possible applications
Summary and trends
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30. Process energy sources for the electrochemical machining process
and hybrid machining with ECM
Dr.-Ing. Dipl.-Phys. Hans-Peter Schulze 1
Dipl.-Ing. M. Läuter1
Prof. Dr.-Ing. G. Wollenberg1
Dr.-Ing. Maria Zybura-Skrabalak2
Dr.-Ing. Anjali K De Silva3
The End
1 Otto-von-Guericke University Magdeburg
Institute for Fundamental Electrical Engineering and EMC
2 IOS Krakow
3 Glasgow Caledonian University
Department of Engineering
Title
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