Upload
awateff-al-jefry-ii
View
1.564
Download
94
Embed Size (px)
Citation preview
INTRODUCTION
OF ELECTRIC DISCHARGE
MACHINING
(EDM)
Electric discharge machining (EDM) is a manufacturing process whereby a wanted shape of
an object of workpiece is obtained using electrical discharges (sparks). The material removal
from the workpiece occurs by a series of rapidly recurring current discharges between two
electrodes, separated by a dielectric liquid and subject to an electric voltage.
Introduction of EDM Die Sinking Machine
EDM die sinking machine consists of an electrode and workpiece that are submerged in an
insulating liquid such oil or, less frequently, other dielectric fluids. The electrode and
workpiece are connected to a suitable power supply.
As the electrode approaches the workpiece, dielectric breakdown occurs in the fluid forming
a plasma channel and a small spark jumps. These sparks usually strike one at a time because
it is very unlikely that different locations in the inter-electrode space have the very identical
local electrical charachetistics which would enable a spark to occur simultaneously in all
such locations.
The EDM die sinking process is most widely used by the mould-making tool
and die industries, but is becoming a common method of making prototype and production
parts, especially in the aerospace, automobile and electronics industries in which production
quantities are relatively low.
Brand from YIHAWJET ENTERPRISES CO.
Example branded from YIHAWJET ENTERPRISES CO.
TOOLS FOR EDM DIE
SINKER
EDM DIE SINKER COMPONENT
Power Supply
The power supply controls the electrical discharges and
movement of the electrode in relation to the workpiece
2. MACHINING 3 AXIS : X, Y, Z
ELEVATING WORK TANK
FLUID DIE ELECTRIC
The Method Die electric fluid
o The border area sparking from oxsigen.
o Produce to help sparking area electrode and workpiece.
o As coolant fluid
o Function to outside dust metal from workpiece.
The type of Fluid Die Electric
o Light lubricant oil
o Transformer oil
o Silicon – base oil
o Corbon tetrachloride
o Kerosene
ELECTRODE
The Character electrode specimen
o The low erosion
o The good eklectrical flow.
o The high efficiency to dismiss high carbon steel.
The electrode specimen
o Copper
o Copper tungsten
o Graphite
OPERATION OF
ELECTRICAL
DISCHARGE MACHINE
(EDM)
Die-sinking EDM systems, the electrode (cutting tool) and workpiece are
held by the machine tool.
The power supply controls the electrical discharges and movement of
the electrode in relation to the workpiece.
During operation the workpiece is submerged in a bath of dielectric fluid
(electrically nonconducting).
(Die-Sinking EDM is also called Sinker, Ram-Type, Conventional, Plunge
or Vertical EDM)
• During normal operation the electrode never touches the workpiece, but
is separated by a small spark gap.
• The electrode (plunger) can be a complex shape, and can be moved in X,
Y, and Z axes, as well as rotated, enabling more complex shapes with
accuracy better than one mil.
• The spark discharges are pulsed on and off at a high frequency cycle and
can repeat 250,000 times per second. Each discharge melts or vaporizes
a small area of the workpiece surface.
• The amount of material removed from the workpiece with each pulse is
directly proportional to the energy it contains.
• Plunge EDM is best used in tool and die manufacturing, or creating
extremely accurate molds for injection-molding plastic parts.
• The dielectric fluid performs the following functions:
It acts as an insulator until sufficiently high potential is
reached .
Acts as a coolant medium and reduces the extremely high
temp. in the arc gap.
More importantly, the dielectric fluid is pumped through
the arc gap to flush away the eroded particles between the
workpiece and the electrode which is critical to high metal
removal rates and good machining conditions.
• A relatively soft graphite or metallic electrode can easily machine
hardened tool steels or tungsten carbide. One of the many attractive
benefits of using the EDM process.
THE PROGRAM OF
EDM DIE SINKER
CODE COMMAND
o Machining
o G100 – Single Machining for rough process
o G101 – Bottom stopped simple
o G103 – Through machining
o G104 – Corner machining
o Positioning
G110 – Point
G111 – Line / grid (setting m/c positions on line/grid)
G112 – Arc/circumference
G113 – Dispersed (setting dispersed position)
G114 – Plural Coordinate (setting m/c positions in plural
cord systems)
G115 – Split positioning (repeated positioning in each m/c
process)
o Measuring
G120 – Edge face (positioning to edge process)
G121 – Groove/hole (positioning center of groove/hole)
G122 – Plate/column (positioning center of plate/column)
G124 – Center Holes (positioning to center plural holes)
G125 – Measure/sphere (positioning spindle ball/table)
G126 – Electrode/sphere (positioning electrode/sphere ball)
o Auxiliary
G131 – Automatic tool changer
G133 – G function processing
G134 – M function processing
FLUIDS IN
EDM
DIE SINKER
As mentioned the dielectric fluid acts as an insulator between the electrode
and the mold cavity. There are many dielectrics to choose from based on the
insulation properties of the fluid. Air is not a very good insulator. Water is best.
But water has a few drawbacks. First, it causes rust. Second, the electrical
discharge separates the water into pure hydrogen and pure oxygen. A very
explosive pair. A good compromise then is kerosene. No rust problem and no
dangerous gasses are produced with kerosene.
The dielectric must be constantly filtered, cooled and recirculated. A great deal
of heat is generated during the EDM process and the dielectric absorbs the
most of it. Additionally the process creates a lot of debris and this needs to be
filtered out of the system.
The type of Fluid Die Electric
o Light lubricant oil
o Transformer oil
o Silicon – base oil
o Corbon tetrachloride
o Kerosene
THEORY OF
ELECTRODE IN EDM
DIE SINKER
An electrode is a conductor through which electric current is passed. Found in
variable forms, electrodes may be wires, plates, or rods. An electrode may be
constructed of metal, such as copper, silver, lead, or zinc. However,
an electrode may also be made of a nonmetal substance, such as carbon.
An electrode passes current between a metallic part and a nonmetallic part of
an electrical circuit. Most frequently, conductors that are metallic carry
electrical current. In other circuits, however, current is passed through a
nonmetallic conductor.
In an electrochemical cell, an electrode is called either an anode or a cathode.
An anode is an electrode at which current leaves the cell and oxidation takes
place. For example, an anode is the positive electrode in a storage battery.
A cathode is described as a negative electrode. Current enters the cell at the
cathode and reduction takes place. Electrons are repelled from the cathode.
When it comes to certain electric devices, like electric batteries, the anode may
actually be negative and the cathode may be positive. In such cases, a
conversion of non-electric energy to electric energy occurs and current flows
from the negative electrode to the positive electrode. However, most familiar
electronic devices involve current that flows from the positive electrode or
anode to the negative electrode or cathode.
TYPES OF ELECTRODES
1. Copper
2. Copper tungsten
3. Graphite
4. Brass
EXAMPLE
PRODUCTS MADE
FROM
EDM
CONCLUSION
Die-sinking EDM systems, the electrode (cutting tool) and workpiece are held
by the machine tool. The power supply controls the electrical discharges and
movement of the electrode in relation to the workpiece. During operation the
workpiece is submerged in a bath of dielectric fluid (electrically
nonconducting). (Die-Sinking EDM is also called Sinker, Ram-Type,
Conventional, Plunge or Vertical EDM)