1.0 TITLE: Production Technology on Non-Traditional Machining
[Electrical Discharge Machining (EDM)]
2.0 OBJECTIVE:-To design a basic NC program for Electrical
Discharge Machining (EDM) wire cut. - To cut a product using the
Electrical Discharge Machining (EDM) wire cut.
3.0 INTRODUCTION:Electrical discharge machining(EDM), sometimes
colloquially also referred to asspark machining,spark
eroding,burning,die sinking,wire burningorwire erosion, is a
manufacturing process whereby a desired shape is obtained using
electrical discharges (sparks).Material is removed from the
workpiece by a series of rapidly recurring current discharges
between twoelectrodes, separated by adielectricliquidand subject to
an electricvoltage. One of the electrodes is called the
tool-electrode, or simply the "tool" or "electrode", while the
other is called the workpiece-electrode, or "workpiece".When the
distance between the two electrodes is reduced, the intensity of
theelectric fieldin the volume between the electrodes becomes
greater than the strength of the dielectric (at least in some
point, which breaks, allowing current to flow between the two
electrodes. This phenomenon is the same as thebreakdown of a
capacitor (condenser)(see alsobreakdown voltage). As a result,
material is removed from both electrodes. Once the current stops
(or is stopped, depending on the type of generator), new liquid
dielectric is usually conveyed into the inter-electrode volume,
enabling the solid particles (debris) to be carried away and the
insulating properties of the dielectric to be restored. Adding new
liquid dielectric in the inter-electrode volume is commonly
referred to as "flushing". Also, after a current flow,
thedifference of potential between the electrodes is restored to
what it was before the breakdown, so that a new liquid dielectric
breakdown can occur.
Wire-cut EDM
The wire-cut type of machine arose in the 1960s for the purpose
of making tools (dies) from hardened steel. The tool electrode in
wire EDM is simply a wire. To avoid the erosion of material from
the wire causing it to break, the wire is wound between two spools
so that the active part of the wire is constantly changing. The
earliestnumerical controlled(NC) machines were conversions of
punched-tape vertical milling machines. The first commercially
available NC machine built as a wire-cut EDM machine was
manufactured in the USSR in 1967. Machines that could optically
follow lines on a master drawing were developed byDavid H.
Dulebohn's group in the 1960s at Andrew Engineering Company for
milling and grinding machines. Master drawings were later produced
bycomputer numerical controlled(CNC) plotters for greater accuracy.
A wire-cut EDM machine using the CNC drawing plotter and optical
line follower techniques was produced in 1974. Dulebohn later used
the same plotter CNC program to directly control the EDM machine,
and the first CNC EDM machine was produced in 1976.
4.0 APPARATUS: EDM wire cut Machine, Aluminium workpiece, NC
Programming, copper wire electrode.
EDM Wire Cut MachineWire Copper Electrode
4.1 INDUSTRIAL APPARATUS:
1. Mitsubishi EDM Wire Cut2. Electrochemical machine(ECM)
3. CNC Laser Cutting Machine5.0 EXPERIMENTAL PROCEDURE:
1. Starting a CNC EDM wire cut machines.2. Write a CNC
program.3. Prepare and display graphics using graph paper.4.
Coordinate offset coordinate position of the wire cutting and die
on the workpiece.5. Programming and cutting operations on the
machine.6. Stop the machine CNC wire cut EDM
Safety precautions when handling EDM machines1. Make sure there
are no leaks in the tank dielectric liquid tank hose and pipe
connections.2. Make sure a fire extinguisher near the machine for
use in emergencies.3. Make sure the materials are installed in
areas where the right job.4. Make sure the electrodes are not
touching the thing work.5. Make sure the cutting wire is not
touching things work.6. Make sure each cable there is no leakage.7.
Clear oily liquid that is in place the working substance during the
installation process.8. Clean all dirt in the tank desk and storage
tanks.9. Wear appropriate clothing while using machines.
6.0 RESULTS:
NC PROGRAMMINGN100 G00 G21 G90;N102 G92 X0. Y10. I15.;N104
M60;N106 M83;N108 M81;N110 S101 D1;N112 G41 G1 X15. Y5.;N114 G01
X10. Y5.;N116 X5. Y10.;N118 X15.;N120 G03 X15. Y15. J2.5;N122 G01
X10. Y15.;N124 X10. Y20.;N126 X15.;N128 G03 X15. Y25. J2.5;N130 G01
X5. Y25.;N132 G01 X10. Y30.;N134 X21. Y30.;N136 G02 X15. Y5.;N138
G01 X15. Y5.;N140 G40 X0.;N142 M50;N144 M30;
7.0 DISCUSSION & ANALYSIS:
In the process of using Electrical- Discharge Machining (EDM)
wire cut machine, we are using copper wire of 0.2mm diameter to cut
Aluminium plate which has thickness 5mm. At the end of the process,
we got the end product with the desire shape which is the shape
above. The process to cut the workpiece took about 15 minutes.
After we get the real product, we do some analysis regarding its
dimensional. We have measure the output and get the same measure as
the drawing. Therefore, we know that EDM wire cut machine could
produce accurate product base on the drawing. As our product is
small with 30mm x 30mm and the machine could cut it, so the machine
is capable to cut small and complex shape. Wire EDM cutting, also
known aselectrical discharge machining, is a process that uses an
electrically energized thin wire to slice through metal. Wire EDM
cutting uses rapid, controlled, repetitive spark discharges from
the wire to the work piece, thereby eroding the metal away. The
work piece must be electrically conductive. Wire EDM can cut
material thickness from only a few thousandths of an inch to
several inches. Custom tooling is generally not needed. Wire EDM
cutting can provide high dimensional accuracy for close fitting
parts. The process can make sharp inside corners. The machine also
can cut most any simple or complex 2D shape including cutouts and
thin walls, intricate openings and sharp inside corners. Cost
optimization options for wire EDM cutting include: Reducing cut
surface area Stacking parts during cutting Minimizing the number of
holes and cutouts Creating holes by providing a small gap
connecting the hole to the outer edge.Wire EDM Design
Considerations Edges are smooth but matte. Typical surface finish
is between 16 and 64 microinches. The edges of the finished work
piece will have virtually no burrs. Kerf width typically ranges
from 0.001" to 0.012".Sharp internal corners will be slightly
rounded (typically with radius ~.008").7.1 Advantages and
Disadvantages of Edm-Wire Cut
EDM-Wire Cut also has its own particular advantages. The machine
capability is cutting materials regardless of its hardness.
EDM-Wire Cut is much faster than EDM. It can cuts intricate shapes,
narrow slots, small products and others. Furthermore no burrs
generated during the process. The wire electrodes used are much
cheaper than shaped electrodes in EDM. Nowadays, EDM-Wire Cut
cables to cut tapered shape products.Electrical Discharge Machining
or EDM is a highly accurate method of part production. Wire EDM
technology is essential for higher tolerance parts and repeatable
tooling. Tolerances are held to .0002" in our temperature
controlled facility.Achieving high accuracy and tighter tolerances
is essential for many industries such as aerospace, medical,
injection molding and tool and die. Besides that, EDM-Wire Cut also
has disadvantages. The EDM-Wire Cut Machine more expansive than
other machine. High skills are required to handle the machine. The
work piece only conductors can be machine. EDM-wire cut have slow
material removal rate (MRR) and less flexible compared others
machine.
8.0 CONCLUSION:
The desired objectives have been successfully implemented. Any
guidance given by lecturers is very useful and effective. We have
been successfully using CNC EDM wire cut machine with skill and
know how to enter the program and run machine for the design of the
products made. In addition, we also know how to apply the program
to form the G-code to get the result as above. All that was taught
to us was really helpful to our advantage as we go intothe working
world later.
9.0 RECOMMENDATION:
One of the most important recommendations to buy EDM-Wire Cut is
that due to the ability to cut any material regardless of its
hardness but only conductor materials. Besides that, the absence of
all-mechanical forces makes it possible to machine fragile parts
without distortion. It is so recommended due to its high accuracy
thus producing a high quality product. Less labour is required to
operate but must be well trained. This will reduce overall
production cost and increase profit of the company.
10.0 REFFERENCES:
Krar, Stephen F. and Gill, Arthur R. (2003)Exploring Advanced
Manufacturing Technologies, Industrial Press Inc. Jameson, E. C.
(2001).Electrical Discharge Machining
www.thomasnet.com/articles/custom.../Wire-Cut-EDM
www.edmmachining.com/wire_edm.htm Todd, Robert H.; Allen, Dell K.;
Alting, Leo (1994).Manufacturing Processes Reference Guide.
Industrial Press Inc.