Electrical Discharge Machining | Non-Conventional Machining Process

Electrical discharge machining (EDM) is an essential manufacturing process for a wide range of products and industries. From medical implants to aerospace components, EDM is used to create complex shapes and designs that would be otherwise impossible to produce. EDM works by using electrical sparks to erode metal, meaning that it can be used on any conductive material.

This makes it an extremely versatile technology that can be used for a wide range of applications. In this article, we will take a look at the history of EDM and how it has developed over the years. We will also explore the different types of EDM machines and their applications.

What is Electrical Discharge Machining?

Electrical Discharge Machining (EDM) is a machining process that uses a pulses of electrical current to remove material from a workpiece. The process works by using an electrode to discharge sparks of electricity onto the workpiece. The sparks remove small pieces of material from the workpiece, which can be anything from metal to plastic. EDM is a precise machining process that can be used to create complex shapes and forms. It is often used to produce parts for the aerospace and medical industries.

Non-conventional machining processes

In recent years, many new materials have been developed. These include titanium alloys, hast alloys, nimonic alloys, etc. These materials cannot be machined accurately with the help of the conventional machining process so a different method of machining has to be adopted. These new methods of machining is called non-conventional type or unconventional machining process. This type of process generally uses ultrasonic, plasma arcs, laser beams, chemicals, and electrochemicals for machining purposes.

Electrical Discharge machining

In this process, metal is removed from the surface of the workpiece by erosion. The erosion is caused by the electric spark produced between the workpiece and the tool. This process consists of a tank in which a fixture is placed inside. The workpiece is held in the tank with the help of a fixture. The tank is filled with a di-electric fluid such as kerosene, white spirit, mineral oil, and paraffin. These di-electric fluids do not conduct electricity.

The work piece is connected to the positive terminal of the battery (usually a D.C supply). The tool is held vertically over the work piece. Graphite, copper, brass or tungsten is generally used for making tools. The tool is hollow. It is connected to the negative terminal of the D.C supply. This makes the tool to act as cathode. A gap in the range of micron is generally kept between the work piece and the tool. In this gap the di-electric fluid is passed through in a very high pressure.

When the power supply is given an electric spark is produced in the gap between the tool and the work piece. Because of the spark heat is generated in the gap. The heat starts makes the surface of the work piece to melt. Thousands of sparks occur per second across the gap. The forces due to the spark tear thee particle of molten metal from the work piece. The tool is connected to the negative terminal to minimize wear on the tool.

Servo mechanism is used to feed the tool and maintain a constant gap between the tool and the work piece. The di-electric fluid also acts like coolant and carries away the eroded metal particle.

Advantages of Electrical Discharge Machining

· All types of material which can conduct electricity can be machined using this method.

· The mechanical properties of the work piece are not affected by this process.

· Surface finish in levels of micron is possible using this method.

· All types of complicated shape can be made on the tool which can again be obtained on the work piece.

· It is less time operation.

· The hardness of the work piece is not a factor as long as the material conducts current it can be machined.

· No stress is applied on the work piece so thin work pieces can also be machined.

Disadvantages of Electrical Discharge Machining

· Very high power consumption.

· Only electrically conductive metals can be machined.

· Perfect square corners cannot be manufactured.

· Redressing of tools is necessary for deep holes.

Application of Electrical Discharge Machining

· Used for die sinking.

· Used to cut off rods.

· Used for making intricate shapes.

· Used for polishing of tools, cutters, and broaches.

· Used for accurate drilling of very small holes, slots, etc.

· Profiles and cavities can be formed on hard and brittle like Brittle materials tungsten carbide using this method.