13-09-2013, 12:50 PM
ADVANCED MATERIAL REMOVAL PROCESSES
[attachment=57995]
Die-Sinker EDM and its Systems
Die-Sinker EDM is known by different names such as Ram EDM, sinker EDM, vertical
EDM and plunge EDM. The process is generally used for producing blind cavities. In
die-sinker EDM, the electrode and workpiece are submerged in an insulating liquid such
as oil or other dielectric fluids. The electrode and workpiece are connected to a suitable
power supply. An electrical potential is generated between the tool and the workpiece
through the power supply. As the electrode approaches workpiece, the dielectric break
down starts taking place in the fluid. Due to this activity, a plasma channel starts forming
and sparks jump from the electrode to the workpiece leading to material removal from the
workpiece. The principle of die-sinking EDM is shown in Fig. 3.10.1 and the schematic
of die-sinker EDM process is shown in Fig. 3.10.2
Dielectric and its Circulation System
The dielectric fluids used in EDM operations are of different types. The most popular
dielectric fluids are hydrocarbon oil (kerosene in particular). The other fluids used are
transformer oil, paraffin oil; silicon based oil, or de-ionized water. The selection of an
appropriate dielectric fluid depends upon its various chemical and fluidic properties
(such as flash point, dielectric strength, viscosity, specific gravity and color)
Servo System
The servo system is commanded by signals from gap voltage sensor system in the power
supply and it controls the in-feed of the electrode to precisely match the required rate of
material removal. At times stepper motor can be used instead of a servomotor. As soon as
the gap voltage sensor system determines bridging of some pieces of electrically
conductive materials between the electrode and work-piece, the servo system
immediately reacts and reverses the direction. The process is restored when the gap is
flushed by the dielectric fluid. When the gap becomes clear, the in-feed resumes and
cutting process continues.
[attachment=57995]
Die-Sinker EDM and its Systems
Die-Sinker EDM is known by different names such as Ram EDM, sinker EDM, vertical
EDM and plunge EDM. The process is generally used for producing blind cavities. In
die-sinker EDM, the electrode and workpiece are submerged in an insulating liquid such
as oil or other dielectric fluids. The electrode and workpiece are connected to a suitable
power supply. An electrical potential is generated between the tool and the workpiece
through the power supply. As the electrode approaches workpiece, the dielectric break
down starts taking place in the fluid. Due to this activity, a plasma channel starts forming
and sparks jump from the electrode to the workpiece leading to material removal from the
workpiece. The principle of die-sinking EDM is shown in Fig. 3.10.1 and the schematic
of die-sinker EDM process is shown in Fig. 3.10.2
Dielectric and its Circulation System
The dielectric fluids used in EDM operations are of different types. The most popular
dielectric fluids are hydrocarbon oil (kerosene in particular). The other fluids used are
transformer oil, paraffin oil; silicon based oil, or de-ionized water. The selection of an
appropriate dielectric fluid depends upon its various chemical and fluidic properties
(such as flash point, dielectric strength, viscosity, specific gravity and color)
Servo System
The servo system is commanded by signals from gap voltage sensor system in the power
supply and it controls the in-feed of the electrode to precisely match the required rate of
material removal. At times stepper motor can be used instead of a servomotor. As soon as
the gap voltage sensor system determines bridging of some pieces of electrically
conductive materials between the electrode and work-piece, the servo system
immediately reacts and reverses the direction. The process is restored when the gap is
flushed by the dielectric fluid. When the gap becomes clear, the in-feed resumes and
cutting process continues.