Abrasive Jet Machining (AJM)

In AJM,a mixture of compressed gas and abrasive particles are used and it is sprayed with high velocity on the work surface.Compressor is used to produce high pressure and then this high pressure gas is guided to a vibrating mixing chamber through different valve mechanisms.the amplitude of vibration decides how much of abrasive particles get mixed with the compressed gas.then this mixture is transformed to a high velocity jet through a nozzle of reducing cross-section.In order to eliminate the wear of nozzle,it is usually made with tungsten carbide.

Specifications:

• Gas used:Air,Nitrogen,Co2


• Abrasive particles:Aluminium oxide powder,Silicon-carbide,Glass powder,Dolomite(light cleaning),Sodium carbonate(Using for extra fine cleaning).


• Jet velocity:300M/S


• Nozzle pressure:0.5N/MM2

LASER Beam Machining (LBM)

LASER is produced by the Rubi  Cystal (crystalline Aluminium Oxide) with the help of a Xenon filled flash lamp.The Rubi crystal is dipped with Chromium Oxide.the flashes are produced by discharging of a large capacitor.this flashes excites the chromium particles to a higher energy level.so when the flash stops the Chromium particles returns to ground level with emitting light energy.the emission from all the Chromium particles together constitutes LASER.The LASER is reflected in between the two reflecting surfaces.so more Chromium particles get excited an 'avalanche' of light emissions takes place.this high energy beam LASER gets out of the Rubi crystal through the partially reflecting end and it is concentrated on the workpiece by lens.For the production of the LASER,it is essential to have a low temperature for the Rubi crystal.so it is provided by the liquid Nitrogen passing through the space in between Rubi crystal and flash lamp.For the production of the flash,it is essential to have high temperature.so hot air is passed over flash lamp.

Ultra Sonic Machining (USM)

Material is removed by the vibration of tool in the ultra sonic range of frequency.usually 15KHz-25KHz.A high frequency current is passed through the coil wounded over the Nickel lamination.so the vibrations are produced due to magnetic effect.this vibration is transferred to the tool through the tool holder or horn.An abrasive slurry is continuously pumped to the space between tool and workpiece.the abrasive particles attains velocity from the tool and fit on the workpiece.so the material get removed.The shape of the horn is of reducing cross-section and it acts as a mechanical amplifier of vibrations.the tool is soldered or welded to the tool holder.

Specifications:

• Abrasive particles-Aluminium Oxide,Silicon Carbide,water
• Voltage-220V
• Current-12A

Electro Chemical Machining (ECM)

In ECM,we are using the principle of electrolysis.usually metal is removed from the anode and deposited at cathode.so here the workpiece is made anode and the tool is made cathode.Here we are using hollow tube shaped tool coated with insulating materials to prevent metal deposition.The electrolyte is continuously pumped through the tube in to the workpiece.so the metal is removed from the workpiece and fleshed along with the electrolyte.The electrolyte is filtered and again re-circulated.

The functions of the electrolyte are:

1. To complete the circuit.
2. As a coolant.
3. Cleaning.

Specifications:

• Tool-Titaniam,Copper,Stainless steel,etc..
• Tool Coating-Teflon.
• Electrolyte-2% of Na Cl solution.
• DC Voltage-5V-30V

Electrical Discharge Grinding (EDG)

Grinding wheel used is made up of graphite and it is negatively charged.Workpiece is mounted on the automated table with the work pan in which dielectric fluid is filled.The workpiece is positively charged.There is no direct contact between workpiece and grinding wheel.the grinding is done by the intermittent sparks between the wheel and workpiece.

Application:

It is mainly used for grinding  the carbide materials and brittle materials.grinding on two dissimilar materials can be done simultaneously using this method.

Specification:

• Gap=0.013MM-0.073MM
• Speed of wheel=0.5M/S-3M/S

Wire Cut Electric Discharge Machining (WCEDM)

This process is also known as 'Travel-Wire EDM'.In this machining,the tool used is copper or bras wire.A hole is pre-drilled on the workpiece through which we pass the electrode (Copper wire).The copper wire is stretched between two wheels and continuously travelling from source spool.the take up spool.Principle is same that of the EDM.the wire is made cathode and the workpiece is made anode.the work piece is mounted on a CNC table,movement of which is programmed.The dielectric fluid is spayed to the cutting zone.the usually used dielectric fluid is De-ionised water.

Advantages:

Using this method,we can cut complex 2D shapes from the workpiece.

Electric Discharge Machining(EDM)

• The tool is made cathode and the workpiece is made anode.there is a small gap between anode and cathode.
• A spark is produced by the discharge between anode and cathode through the gap and it is intermittent(not continues).
• Due to this spark,a higher temperature of 12000° centigrade which produce at that time and the material get vapourised.
• A dielectric fluid(Electrically non-conductive) is used to enhance the spark generation and it also clean the 'debris'(wast).
• A servo control mechanism is used to provide a constant gap between anode and cathode.

Specifications:

• Voltage-50V-200V
• Current-15A-500A
• Gap-0.025MM-0.075MM
• Tool-Copper,Graphite,Brass,Tungsten Carbide

Functions of dielectric fluid:

• Insulation between anode and cathode
• Cooling
• Cleaning

Eg:-Transformer Oil,White Spirit,Kerosene

Un-Conventional Machining(Non-Traditional Machining)

In the conventional methods of machining,we were using a harder tool against the relatively softer workpiece and material were removed in the form of chips.But in the non-traditional methods,we are using other technology such as electric spark or chemical energy,etc.for the machining to optain a better result.

Advantages

• Tool need not harder than the workpiece.
• More complex shapes can be machined.
• Brittle materials can be easily machined by using such processes.
• Better surface finish.

Disadvantages/Limitations

• Cost is high.
• Relatively slow process.
• The work should electrically conductive in most of cases.

There are four (4) methodes for unconventional machining.they are:

• Thermal Energy Method

Eg:-

1. EDM-Electric Discharge Machining
2. EDG-Electric Discharge Grinding
3. WCEDM-Wire cut Electric Discharge Machining
4. LBM-LASER Beam Machining

• Electro Chemical Energy Method

Eg:-

1. ECM-Electro Chemical Machining

• Chemicam Energy Method

Eg:-

1. ..................

• Mechanical Energy Method

Eg:-

1. USM-Ultra Sonic Machining
2. AJM-Abrassive Jet Machining
3. WJM-Water Jet Machining

In thermal energy methods,we are producing a high temperature using electric spark,LASER,etc..

In electro chemical methods,we are using the principle of electrolysis.

In chemical energy methods,we are using a controlled erosion using proper chemicals.

In mechanical energy methods,the material is removed using mechanical force.inthis method,the tool need not be electrically conductive.