Bài giảng môn Tia Lửa điện English SPKT TPHCM
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Electrical Discharge Machining
(EDM) Technology
Dr. Hoang Trung Kien
2015-2016/ 2nd semester
CHAPTER I
INTRODUCTION
MANUFACTURING PROCESS
Manufacture
Assembly
Design
Quality Control
Factory
Call
Packing
Service
Delivery
MANUFACTURING TECHNOLOGY
• Casting
• Molding
• Forming
• Cutting (machining)
• Joining
• Additive manufacturing
• Others
MACHINING TECHNOLOGY
• Traditional
- Turning
- Milling
- etc.
• Non-traditional
- EDM, ECM
- Laser cutting
- etc.
WHAT IS EDM?
• Electrical discharge machining is:
o a manufacturing process
o a thermal process
o a non-contact machining process
o an electrical process
EDM SYSTEM
Nozzle holder
Workpiece
Reservoir/
Filtration
Dielectric
circulation
Dielectric
medium
Tool
Power
supply
Pump
TYPES OF EDM
Die-sinker EDM
Wire cut
Drilling EDM
Milling EDM
WEDM SYSTEM
New wire
spool
Brush
Wire-guide
Tension
adjustment
Pulse
generator
Wire-guide
Workpiece
Used wire
collected spool
DISCHARGE CONTROL
1. Transistor-type pulse generator
Control pulse
Tool
Workpiece
DISCHARGE CONTROL
2. RC-type pulse generator
Tool
Workpiece
GAP CONTROL
Gap voltage
Contact sensor
Workpiece
Reservoir/
Filtration
Dielectric
circulation
Dielectric
medium
Tool
Pulse
control
Tool feed
controller
Z-stage
Power
supply
Pump
Reference
voltage
HISTORY
• Important timeline
1770
1943
1960s
1976
EDM erosion
EDM machine
Wire EDM
CNC EDM machine
APPLICATIONS
•
•
•
•
•
•
Tool and die making
Aerospace, automobile…
Medical implant
Cavities with thin walls
Small hole drilling
Etc.
WHAT TO LEARN?
IN TEXTBOOK
• Fundamentals of EDM
• EDM system
• EDM parameters
• Dielectric
• Electrodes
• EDM CNC and programming
• Others
OUTSIDE OF TEXTBOOK
Everything about EDM that …
you should know !
RESEARCH AREAS
EDM
research areas
Optimizing the
process variables
Monitoring &
control the process
Electrical &
Electrode
Pulse/time Fuzzy
Radio
Non-electrical
design &
domain
logic frequency
parameters
manufacture
Improving the
performance measures
MRR
TWR
Surface
quality
EDM
developments
Hybrid
EDM
machining
applications
process
SUMMARY
•
•
•
•
History
Definition
Classification
Applications
CHAPTER II
FUNDAMENTALS OF EDM
ELECTRICAL DISCHARGE
• What is electrical discharge?
Current (flow of charge)
Breakdown
Plasma
Ionization
Voltage
Arc
Gas, liquid or solid
DISCHARGE PROCESS
Electron
Atom or molecule
Ion
−
+
Primary
initiation
ICCD image capture by
E.H.R. Gaxiola (1999)
+ ̶ ̶
̶
+
+ ++
̶
+
+
̶
+
̶
̶
+
+
+
+
+ + + +
̶
̶
+
++
+
̶
̶
+
+ ̶
+
̶
+
++
̶ ̶
+
Secondary
initiation
Cathode
(-)
Townsend avalanche (thác) theory
Anode
(+)
DISCHARGE PROCESS
U
Uo
Ue
td
te
to
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ie
t
<B.M. Schumacher / Journal of Materials Processing Technology 149 (2004) 376–381>
DISCHARGE PROCESS
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Preparation phase for ignition (td)
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