edm ppt
TRANSCRIPT
1
P R E S E N T E D B Y,
U M A . B . S
I I S E M M T E C H
( 1 M S 11 M S C 0 1 3 )
D E PA RT M E N T O F M E C H A N I C A L E N G I N E E R I N G
L E C T. M R . M O H A N D A S . K . N
Electric Discharge Machining
2
Unit 2: Thermal metal removal process
Principle of operation – Uma. B. S
EDM basic circuitry – Gajaana Anne, Anand Babu
Dielectric fluids, process parameter – Mrudula Prashanth
Benefits, limitations and applications - Manjunath
3
Presentation Content
Introduction
Popularity of EDM
Basic principle of EDM
Mechanism of metal removal
4
Nontraditional Machining and Thermal Cutting Processes
Nontraditional machining :
Material removal process- mechanical, thermal, electrical or chemical energy
Do not use a sharp cutting tool in the conventional sense
Thermal cutting process :
Thermal energy generally applied to a small portion of the work surface, causing removal by erosion and/or vaporization
Thermal energy is generated by conversion of electrical energy
5
EDM highlights
Energy type: Thermal
Mechanics of metal removal: Erosion and/ or vaporization
Energy source: Electric spark
Medium: Dielectric fluid
Spark Gap: 10-125µm
Maximum metal removal rate: 5*10³ mm³/min
Spark frequency: 200-500,000Hz
Peak voltage: 30-250 volts
History In1770s, discovered by Joseph Priestly.
In 1943 first EDM Machine (Lazarenko & Lazarenko)
Developed in the mid 1970s In the mid 1980s, the EDM
techniques were transferred to a machine tool
Today, it is a viable technique that helped shape the metal working industry
6
EDM
7 Electrically conductive materials
Physical properties of w/p not a barrier
(Hastalloys, nimonics, waspalloy) HSTR metals
No mechanical deformation
Surface produced – contains multitude of small craters (helps in oil retention)
Metal removal due to thermal effect – no bulk heating
Process can be automated with less difficulty
Popularity of EDM
8Thermal (Thermoelectric) Processes
EBM - electron beam machining EDM - electrical discharge
machining EDG - electrical discharge
grinding EDWC - electrical discharge wire
cutting LBM - laser beam machining PAM - plasma arc machining Ion beam machining
9
ClassificationEDM
Sinking by EDM
Cutting by EDM Grinding by EDM
Drilling
Die sinking
Slicing using ribbon disc
Wire cutting
Slicing using ribbon
External EDM grinding
Internal EDM grinding
Form grinding
10
Terms in EDM
Spark - The electrical discharge between two conductors
Spark Gap - The space between the workpiece and the electrode at the point of discharge
Overcut - measurement difference between the dimensions of the cavity EDMed and the dimensions of the electrode used to cut the cavity
11
Basic scheme of EDM
12
Component of EDM system
EDM system: A tool (electrode) Work piece A dc power supply Servomotor Dielectric fluid
13
ExactDifficultMachining
Overall view of workpiece and tool
Detailed view of spark gap
14
12
Principle of operation
Application of an electrical potential between tool (electrode) and workpieceCreation of an ionized channelSparkImplosion of the plasma channelMaterial ejection (Erosion and/or vaporization)
15
Mechanism of metal removal
Diagram of electroerosive machining: (1) tool, (2) work-piece, (3) liquid dielectric, (4) electric discharges
16
Fig A. Crater formed on the workpieceFig B. The finished EDM workpiece - several distinct
layers
1
2
3
1. Layer with small globules of removed workpiece metal and electrode
2. the “white” or “recast” layer3. Heat affected zone or annealed layerFig A.
Fig B.
17
References
Advanced Machining Processes – V. K Jain (Pg No.,126)
Unconventional Manufacturing process – M. K. Singh (Pg No.,81)
“Manufacturing science ” – Amitabh Ghosh (Pg No., 329)
HMT production technology
18
THANK YOU
Questions?