22-11-2012, 06:30 PM
Experimental Investigation of Machining Parameters for EDM Using U-shaped Electrode of AISI P20 Tool Steel
[attachment=40757]
ABSTRACT
The correct selection of manufacturing conditions is one of the most important aspects to
take into consideration in the majority of manufacturing processes and, particularly, in processes
related to Electrical Discharge Machining (EDM). It is a capable of machining geometrically
complex or hard material components, that are precise and difficult-to-machine such as heat
treated tool steels, composites, super alloys, ceramics, carbides, heat resistant steels etc. being
widely used in die and mold making industries, aerospace, aeronautics and nuclear industries.
AISI P20 Plastic mould steel that is usually supplied in a hardened and tempered condition.
Good machinability, better polishability, it has a grooving rang of application in Plastic moulds,
frames for plastic pressure dies, hydro forming tools These steel are categorized as difficult to
machine materials, posses greater strength and toughness are usually known to create major
challenges during conventional and non- conventional machining. The Electric discharge
machining process is finding out the effect of machining parameter such as discharge current,
pulse on time and diameter of tool of AISI P20 tool steel material. Using U-shaped cu tool with
internal flushing. A well-designed experimental scheme was used to reduce the total number of
experiments. Parts of the experiment were conducted with the L18 orthogonal array based on the
Taguchi method. Moreover, the signal-to-noise ratios associated with the observed values in the
experiments were determined by which factor is most affected by the Responses of Material
Removal Rate (MRR), Tool Wear Rate (TWR) and over cut (OC).
Background of EDM
The history of EDM Machining Techniques goes as far back as the 1770s when it was
discovered by an English Scientist. However, Electrical Discharge Machining was not fully
taken advantage of until 1943 when Russian scientists learned how the erosive effects of the
technique could be controlled and used for machining purposes.
When it was originally observed by Joseph Priestly in 1770, EDM Machining was very
imprecise and riddled with failures. Commercially developed in the mid 1970s, wire EDM began
to be a viable technique that helped shape the metal working industry we see today. In the mid
1980s.The EDM techniques were transferred to a machine tool. This migration made EDM more
widely available and appealing over traditional machining processes.
The new concept of manufacturing uses non-conventional energy sources like sound,
light, mechanical, chemical, electrical, electrons and ions. With the industrial and technological
growth, development of harder and difficult to machine materials, which find wide application in
aerospace, nuclear engineering and other industries owing to their high strength to weight ratio,
hardness and heat resistance qualities has been witnessed. New developments in the field of
material science have led to new engineering metallic materials, composite materials and high
tech ceramics having good mechanical properties and thermal characteristics as well as sufficient
electrical conductivity so that they can readily be machined by spark erosion. Non-traditional
machining has grown out of the need to machine these exotic materials. The machining
processes are non-traditional in the sense that they do not employ traditional tools for metal
removal and instead they directly use other forms of energy. The problems of high complexity in
shape, size and higher demand for product accuracy and surface finish can be solved through
non-traditional methods.
Introduction of EDM -
Electro Discharge Machining (EDM) is an electro-thermal non-traditional machining
Process, where electrical energy is used to generate electrical spark and material removal mainly
occurs due to thermal energy of the spark.
EDM is mainly used to machine difficult-to-machine materials and high strength
temperature resistant alloys. EDM can be used to machine difficult geometries in small batches
or even on job-shop basis. Work material to be machined by EDM has to be electrically
conductive.
Principle of EDM –
In this process the metal is removing from the work piece due to erosion case by rapidly
recurring spark discharge taking place between the tool and work piece. Show the mechanical set
up and electrical set up and electrical circuit for electro discharge machining. A thin gap about
0.025mm is maintained between the tool and work piece by a servo system shown in fig 1.1.
Both tool and work piece are submerged in a dielectric fluid .Kerosene/EDM oil/deionized water is very common type of liquid dielectric although gaseous dielectrics are also used in certain
cases.
Wire-cut EDM –
Wire EDM Machining (also known as Spark EDM) is an electro thermal production
process in which a thin single-strand metal wire (usually brass) in conjunction with de-ionized
water (used to conduct electricity) allows the wire to cut through metal by the use of heat from
electrical sparks. a thin single-strand metal wire, usually brass, is fed through the workpiece,
submerged in a tank of dielectric fluid, typically deionized water. Wire-cut EDM is typically
used to cut plates as thick as 300mm and to make punches, tools, and dies from hard metals that
are difficult to machine with other methods.
Wire-cutting EDM is commonly used when low residual stresses are desired, because it
does not require high cutting forces for removal of material. If the energy/power per pulse is
relatively low (as in finishing operations), little change in the mechanical properties of a material
is expected due to these low residual stresses, although material that hasn't been stress-relieved
can distort in the machining process. Due to the inherent properties of the process, wire EDM
can easily machine complex parts and precision components out of hard conductive materials.
[attachment=40757]
ABSTRACT
The correct selection of manufacturing conditions is one of the most important aspects to
take into consideration in the majority of manufacturing processes and, particularly, in processes
related to Electrical Discharge Machining (EDM). It is a capable of machining geometrically
complex or hard material components, that are precise and difficult-to-machine such as heat
treated tool steels, composites, super alloys, ceramics, carbides, heat resistant steels etc. being
widely used in die and mold making industries, aerospace, aeronautics and nuclear industries.
AISI P20 Plastic mould steel that is usually supplied in a hardened and tempered condition.
Good machinability, better polishability, it has a grooving rang of application in Plastic moulds,
frames for plastic pressure dies, hydro forming tools These steel are categorized as difficult to
machine materials, posses greater strength and toughness are usually known to create major
challenges during conventional and non- conventional machining. The Electric discharge
machining process is finding out the effect of machining parameter such as discharge current,
pulse on time and diameter of tool of AISI P20 tool steel material. Using U-shaped cu tool with
internal flushing. A well-designed experimental scheme was used to reduce the total number of
experiments. Parts of the experiment were conducted with the L18 orthogonal array based on the
Taguchi method. Moreover, the signal-to-noise ratios associated with the observed values in the
experiments were determined by which factor is most affected by the Responses of Material
Removal Rate (MRR), Tool Wear Rate (TWR) and over cut (OC).
Background of EDM
The history of EDM Machining Techniques goes as far back as the 1770s when it was
discovered by an English Scientist. However, Electrical Discharge Machining was not fully
taken advantage of until 1943 when Russian scientists learned how the erosive effects of the
technique could be controlled and used for machining purposes.
When it was originally observed by Joseph Priestly in 1770, EDM Machining was very
imprecise and riddled with failures. Commercially developed in the mid 1970s, wire EDM began
to be a viable technique that helped shape the metal working industry we see today. In the mid
1980s.The EDM techniques were transferred to a machine tool. This migration made EDM more
widely available and appealing over traditional machining processes.
The new concept of manufacturing uses non-conventional energy sources like sound,
light, mechanical, chemical, electrical, electrons and ions. With the industrial and technological
growth, development of harder and difficult to machine materials, which find wide application in
aerospace, nuclear engineering and other industries owing to their high strength to weight ratio,
hardness and heat resistance qualities has been witnessed. New developments in the field of
material science have led to new engineering metallic materials, composite materials and high
tech ceramics having good mechanical properties and thermal characteristics as well as sufficient
electrical conductivity so that they can readily be machined by spark erosion. Non-traditional
machining has grown out of the need to machine these exotic materials. The machining
processes are non-traditional in the sense that they do not employ traditional tools for metal
removal and instead they directly use other forms of energy. The problems of high complexity in
shape, size and higher demand for product accuracy and surface finish can be solved through
non-traditional methods.
Introduction of EDM -
Electro Discharge Machining (EDM) is an electro-thermal non-traditional machining
Process, where electrical energy is used to generate electrical spark and material removal mainly
occurs due to thermal energy of the spark.
EDM is mainly used to machine difficult-to-machine materials and high strength
temperature resistant alloys. EDM can be used to machine difficult geometries in small batches
or even on job-shop basis. Work material to be machined by EDM has to be electrically
conductive.
Principle of EDM –
In this process the metal is removing from the work piece due to erosion case by rapidly
recurring spark discharge taking place between the tool and work piece. Show the mechanical set
up and electrical set up and electrical circuit for electro discharge machining. A thin gap about
0.025mm is maintained between the tool and work piece by a servo system shown in fig 1.1.
Both tool and work piece are submerged in a dielectric fluid .Kerosene/EDM oil/deionized water is very common type of liquid dielectric although gaseous dielectrics are also used in certain
cases.
Wire-cut EDM –
Wire EDM Machining (also known as Spark EDM) is an electro thermal production
process in which a thin single-strand metal wire (usually brass) in conjunction with de-ionized
water (used to conduct electricity) allows the wire to cut through metal by the use of heat from
electrical sparks. a thin single-strand metal wire, usually brass, is fed through the workpiece,
submerged in a tank of dielectric fluid, typically deionized water. Wire-cut EDM is typically
used to cut plates as thick as 300mm and to make punches, tools, and dies from hard metals that
are difficult to machine with other methods.
Wire-cutting EDM is commonly used when low residual stresses are desired, because it
does not require high cutting forces for removal of material. If the energy/power per pulse is
relatively low (as in finishing operations), little change in the mechanical properties of a material
is expected due to these low residual stresses, although material that hasn't been stress-relieved
can distort in the machining process. Due to the inherent properties of the process, wire EDM
can easily machine complex parts and precision components out of hard conductive materials.