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CUSTOM MANUFACTURING

Electric Discharge Machining Services

Electric Discharge Machining  (EDM)is a Non-conventional machining process.Used for machining very hard materials which otherwise can not be machined using conventional machining processes.This process is also called as spark eroding,spark machining,wire erosion,wire burning etc.In this process,the metal from the workpiece is removed using high frequency electrical spark discharged from graphite or soft metal tools which serve as electrode.

This process is only suitable for metallic or conductive workpiece.

EDM process is very similar to how a spark plug works in the petrol engine.It creates an artificial bolt of lighting in the combustion chamber.The electrical energy that it creates extremely high in order to create a spark, the voltage at the spark plug is nearly between 20000 to 100000 volts.  If you are interested in the working of the engines i have provide a link in the description below:

Please contact us for more customized features and metal parts.

Working Principle

The working principle of the EDM process is based on workpiece metal erosion with application or spark discharge between the tool and the workpiece.

When two current carrying conductors that is anode and cathode are brought in close proximity an electric arc is formed between the two conductors due to which at the point of contact a small amount of metal is eroded leaving small cracks.

This spark generates intense heat causing the metal in this zone of spark to melt and evaporate.

When both the electrode that is anode and cathode is made of the same material, the electrode connected to the positive terminal erodes faster, therefore, the workpiece is generally connected to the positive terminal that is ,it is made anode, generally a small gap of 0.005mm or 0.05mm is maintained between the tool and the workpiece.the spark occurs where the tool and the workpiece are the closest.The shape of the tool is the same as the impression to be generated on the workpiece.

To increase the effectiveness of the process of the tool and workpiece are immersed in the dielectric fluids such as hydrocarbon and mineral oils.

Construction

 DC(direct current)pulse generator. This convert’s the AC power supply into a high pulsed Dc supply responsible for generating a spark between the tool and the workpiece. The tool should be the replica of the shape to be generated on the workpiece and it is connected to the negative terminal of the power supply.

Servo motor as the arc gap is critical.It is used to control the feed of the tool.The spark generator supplies sufficient voltage for spark generation and maintains its discharge.

Dielectric fluid is generally supplied in the form of a jet at the gap between the tool and the workpiece.

Deionized water,Silicone oil, glycol etc. Are generally used as dielectric fluids.

Working

The tool should be the replica of the shape to be generated on the workpiece ,it is connected to the negative terminal of the power supply.

When the power supply is turned on the dc pulse generator supplies a voltage pulse between 40 to 3000 volts.The workpiece is connected to the positive terminal and the stool is connected to the negative terminal.The gap between the tool and the workpiece is filled with the Di-electric fluid. When this high voltage power is supplied to the tool this causes the particles in the dielectric fluid to concentrate.The fluid gets ionized forming a path for the current to flow from the tool to the workpiece. This intense arc generated at the tool and the workpiece interface causes the workpiece material to vapor in this process a small amount of tool material is also eroded.

Once the spark is interrupted the heat is removed by the Di-electric fluid and carries the eroded metal particles.

The movement of the tool is controlled by the servo-motor mechanism which maintains the gap.

    Please contact us for more customized features and metal parts.

    Application of EDM

    • Drilling of micro holes in the metal nozzles

    • EDM can be used for manufacturing of gear wheels

    • Holes or slots in the hard material used for the blades of the turbines ,compressors etc.

    • Thread cutting

    • Engraving operation on hard materials

    • Rotary form cutting.

    Advantages and disadvantages

    Advantages

    A :It can produce complex shapes which otherwise would be difficult to produce using conventional machining processes.

    B:Tolerance of plus or minus 0.005 can be achieved.

    C:Good surface surface finish can be obtained economically

    D:There is no distortion or vibration of tool or workpiece as there is no physical contact between the tool and work piece.

    Disadvantages:

    A:High power consumption

    B:Excessive tool wear durning machining.

    C:This process is only applicable for metallic or conductive material.

    D:Material removal rate is very slow.