NON CONVENTIONAL MACHINING PROCESSES - ALL IN ONE

MECHANICAL TIPS AND STUDY MATERIAL

In order to benifit you more and more I have clubbed all the non conventional machining processes in a single post so that you could get directly what you want inspite of searching it here and there.

Please click on the links given below to directly go to the topic

The first step is to know the basic difference between conventional and non conventional machining processes. This will clear your concept regarding where we use non conventional machining process and what are its advantages.

1) NON-CONVENTIONAL VS CONVENTIONAL MACHINING DIFFERENCE

There are various factors that effect the non-traditional machining processes. These factors can be temperature, grain size, heat, operating environment etc. The machinig varies as these parameters vary. You can get it dirctly by clicking on link below.

2) FACTORS EFFECTING NON-CONVENTIONAL MACHINING PROCESS

Given below are the list of various non-conventional machining processes which you can access here.

3) ABRASIVE JET MACHINING AND WATER JET MACHINING

4) PLASMA ARC MACHINING AND ELECTON BEAM MACHINING

5) LASER BEAM MACHINING AND ELECTRO -CHEMICAL MACHINING



Hope you have liked the materials.......................for any quaries.............. please let us know.........

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GRINDING AND DRILLING MACHINE CLASSIFICATION AND OPERATION

GRINDING MACHINE AND OPERATION

Abrasive grain+bond = Abrasive wheel

ABRASIVE GRAINS USED IN WHEELS ARE:-

• ALUMINIUM OXIDE 
• CERAMICS 
• SILICON CARBIDE 
• CUBIC BORON NITRIDE 
• DIAMOND

 Bonds hold the abrasive particles to the wheels. There are many bonds particles such as

• SILICATE 
• RESINOID 
• VERTIFIED 
• SHELLAC 
• RUBBER 
• OXY CHLORIDE 
• A ABRASIVE WHEEL

BASIC IDEA OF GRINDING:-
A grinder is a machine that performs machining by abrasive action of abrasive wheel which acts as cutting tool.The abrasive wheel has abrasive grains on it which removes small amount of material in form of small chips when wheel comes in contact of work piece. The material removal occurs as a result of shear deformation.

                              Fig:-grinding wheel action

Grinding is basically performed for finishing operation. It can attain high surface accuracy of 0.00002 mm. Mostly it is employed to remove material depth of 0.25 to 0.50 mm depth. But in some cases it can be employed to remove large material from work piece.
Coolant is also used during abrasive action as because large amount of heat is produced during abrasive action due to friction between abrasive wheel and work piece.

• The coolant helps to carry away heat from working region. 
• Carry away burr/machined particles. 
• Lubricates parts . 
• Lets have a look at a grinding machine.

Type of grinding machine:-

• Belt grinder 
• Bench grinder 
• Cylindrical grinder 
• Surface grinder 
• Jig grinder 
• Gear grinder 

1.. BELT GRINDER:-



Fig:-belt grinder

As it is abrasive machining process, it consists of a belt coated with abrasives. This coated abrasive belt is allowed to move over the surface of the work piece.
In actual belt grinders are used to provide surface finish. It removes very small amount of material from the work piece and provides dimensional accuracy.

APPLICATION:-

• Burr removal, stock removal from material. 
• Edge refining /shaping. 
• Polishing. 

2.. BENCH GRINDER:-



Fig:-bench grinder

It is basically mounted on the floor stand or workbench. These generally contain two abrasive wheel as shown in figure. Each abrasive wheel has abrasive grain of different sizes. Both roughing and finishing operation can be performed. They are generally used to shape the tools, their edges. For e.g. lathe tool bits etc.

3.. CYLINDRICAL GRINDERS:-

These are generally employed to obtain cylindrical objects of high surface finish and accuracy. There may or may not be multiple wheels. The work piece is allowed to rotate and grinding wheel makes contact with the work piece. The work piece is supported between tool and stationary wheel.

Apart from this grinder also performs action such as high precision gear manufacturing, acts as drill bit, finishing jigs and surface operation and finishing.

DRILLING MACHINE

A drilling machine a device that uses drill bit and is conventional machining process. Drilling is basically a process of making holes in work piece. The diameter varies from 0.025 mm to 1250 mm. It is a motor fitted device that has tool on the other end and is allowed to move (rotate) at required speed in order to create a new hole or to enlarge the existing hole.

OPERATION:-The process involves rotary tool bit which is pressed against solid work piece. The tool is sharp edged on the entrance side and on the exit side it has it is marked with burrs. The operation starts with supplying electric power to motor which allows it to rotate at high speed. This rotary motion is supplied to the spindle. As the spindle rotates, it intern rotates the tool at high speed. This rotary tool is pressed against the work piece and hence causes shear deformation of work piece.

The operation is mechanically sound as the material removal is accomplished by shear deformation of material layer by layer from inside of the hole, making the hole size increase layer by layer. Drilling machines are used for drilling, boring, countersinking, reaming, and tapping.

The various types of drilling machines available to us are:-

· Vertical drilling machine
· Horizontal drilling machine
· Multiple spindle drilling machine
· Gang drilling machine
· Center drilling machine
· Special purpose drilling machine.

1. VERTICAL DRILLING MACHINE:-

                     FIG:-VERTICAL DRILLING MACHINE

These are most widely used and it consists of vertical tool. The tool moves perpendicular to the work piece and used for mass production. Various tool like reamer, counter sink, drill bit is attached to the vertical spindle which is intern attached with motor as per operation required. As explained in working process, as motor rotates it rotates the spindle, which intern rotates the tool. This type of drilling also support automated operation in mass production process. Drill diameter of up to 12 mm can be easily achieved.

2. HORIZONTAL DRILLER:-

· The machine used for drilling large components like gas pipelines, or removing layer of rock from inside of ground. All this can be done with the help of horizontal driller.
· It is more complex process.

3. GANG DRILLING MACHINE:-

Its working and operation is similar to the vertical drilling machine. The major difference is that such machine has multiple spindle and each spindle carries a tool. Hence at same time such machine can drill number of holes whereas the vertical driller can machine only one hole. Such machine is very effective when we talk about mass production.
Automated production is feasible in such process.

4. MULTIPLE SPINDLE DRILLER:-

In such machine,for each tool there is single motor and multi spindle arrangement is there.
Two or three tools are assembled in one spindle. The advantage of such arrangement is, every tool can work separately at required speed and more than one hole is created at the same time. Such features enables to have automated operation. Used in mass production process.


Objective question on drilling:-

1) Tool used to cut a hole is called

a) Saw

b) Bit

c) Chisel

d) Hammer

2) How many types of drill press are there?

a) 2
b) 3
c) 4
d) 6

3) Drilling operation is done in order to :-

a) Machine the work piece,create hole.
b) Provide surface finish.
c) Both a and b
d) None of them


4) Drilling is a________process.

a) Conventional
b) Non conventional
c) Depends on operation
d) Both a and b


5) For mass production process which process is suitable?

a) Horizontal drilling
b) Vertical driller
c) Gang drilling
d) Multi spindle drilling
e) Both c and d.


6) Material deformation takes place by:-

a) Tensile stress
b) Shear deformation
c) Compressive action

d) Slipping phenomenon.

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BROACHING MACHINE

        BROACHING PROCESS

Points to know:-

• Tool-high speed steel,brazed carbide,alloy steel.
• Work piece-light material like aluminium, plastic, brass etc.
• Tool cutting rate 20-100 feed/minute.

what is broaching?

• Broaching is a conventional (tool-work piece in contact) machining process of removing material from work piece with the help of broach tool.
• The broach tool can perform two operations:-

1.     Linear broaching

2.     Rotary broaching

• Linear broaching:-

In linear broaching the broach tool moves in linear direction against the work piece surface.

• Rotary broaching:-

In such broaching operation broach tool is made to rotate on the axis and pressed against the work piece and cut or produce axis symmetric shape.

2.  What is a broach tool?

 Fig:-Broach tool

The broach tool can be divided into three section:-

1.              Roughing zone--Big teeth

2.              Semi-finishing zone---Small teeth.

3.              Finishing zone---Fine teeth.

The slot is provided near the pull end of tool for attachment in lathe/screw machine. At the beginning of rough teeth, chip breakers are present. These are provided for fracturing the work piece at initial stage.

The broach teeth size increases gradually in size. More is the number of teeth, higher will be the material removal.

          Fig:-broach teeth close look

The feed per tooth determines the material removal rate. The broach tool has unique function of cutting and finishing the work piece in single stroke/feed.

The small and gradually increasing size teeth are made for cutting and larger size tool are made for finishing operation. Each cutting teeth removes small amount of material and larger teeth shapes the work piece to good surface finish.

The machining takes place in forward direction only and no material is removed in return stroke.

3.  Why we use cutting fluid during broaching?

• The reason of using cutting fluid are:-

1.Removes burr/cut particles from cutting region.

2.Carry away heat which is generated due to friction between tool and work piece.

3.Provides lubrication effect to machine parts.

4.  What are classification of broaches?

• Broaches on the mode of usage can be classified as:-

1.Internal broaches.

2.Surface broaches.

In order to machine internal surfaces or key ways various broach operation like solid broach, key way broach, modular  broach are used.

Surface broach is used to produce upper machined surface of work piece. The various process include slot broach, counter broach etc.

APPLICATION:-

• Engine parts, internal components are machined.
• Used in steel industries. etc

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LASER BEAM MACHINING(LBM) AND ELECTROCHEMICAL MACHINING PROCESS

LASER BEAM MACHINING(LBM)PROCESS

1. BASIC IDEA:-

Laser beam machining is a non traditional process where machining takes place without tool in contact with work piece.

2. What is laser:-

LASER means light amplified stimulated emission of radiation. It is monochromatic light or single wavelength light which is unidirectional in nature. These waves are focused on a single point by focusing lens and they become highly intense.

3. What is normal light wave and laser light wave?

A normal light waves has multiple wavelength and is multi directional in nature. This can be observed in electric bulb or rays of the sun. Whereas LASER waves monochromatic in nature (all waves have same wavelength). These are non diverging in nature and are said to be one directional. 

4. How is laser wave generated?

For amplifying light to high intensity, the gain medium (space inside the chamber) is to be supplied with energy, this is called PUMPING.

The light bounces to and fro between the two mirrors in the gain medium and each time it gets amplified and finally all the light waves acquire same wavelength. Hence it becomes monochromatic and of high intensity which is used for verity of purposes.


5. WORKING PROCESS:-

fig:-LBM PROCESS

Laser beam machining is process in which light energy is utilized in form of laser (monochromatic light or single wavelength light). This laser is directed on the work piece and material removal takes place by vaporization process. The laser is focused to very small area (since light is monochromatic) and high energy of 100 MW is applied on that area. The light energy is concentrated optically in LBM process.
         

6. Various types of laser are used. Some of them are as under.

Gas laser 

In gas laser coherent light waves are produced when current is induced through gas. This is the first known laser which produced continuous light source in infrared region by conversion of electrical energy to laser light. The various examples of gas laser are helium-neon laser, argon ion laser etc.

 

Excimer laser

It is generally formed when reactive gases like chlorine etc are added to noble gases like xenon, krypton etc. Under proper electric current and pressure we obtain excimer. It is a excited pseudo molecule which has energy and capable of producing laser beam.

Solid state laser

Solid state laser are also called semiconductor laser and it is characterized by doping of crystals with the ions. The pulses are generated in this type of laser and good beam quality is achieved.

7. APPLICATION:-

• Drilling, cladding.
• Cutting material.
• Welding

8. ADVANTAGES:-

• No heat generation problem.
• Very accurate cut/weld/drill.
• Very small diameter operation is possible.

ELECROCHEMICAL MACHINING

Basic idea

The process includes machining by indirect contact between tool and work piece. The material removal takes place by electrochemical process. The process includes one electrode as cathode, work piece as anode and the electrolyte as medium between them.

Cathode (negative charged) is Tool.
Anode (positive charged) is Work piece.
Electrolyte is Acidic (saline) medium.



         

                                  fig:-ECM PROCESS


WORKING:-

When the circuit is complete, the cathode i.e. tool is advanced towards the anode i.e. work piece.
The electrolyte is forced or pressurized from in between of tool (cathode) as shown in figure.
The gap between tool and work piece is kept between 80-800 micrometer.


USE OF ELECTROLYTE:-

The electrolyte used performs fallowing function:-

It acts as lubricant. Carries debries or metal (found between tool and work piece due to chemical reaction). Removes heat from working region. Provides good machinability. Completes circuit for reaction to take place.Material is removed and gets separated from electrolyte as metal hydroxide. As the tool advances towards the work piece the material from the work piece is removed due to reaction and the same mirror image is obtained on the work piece.

ADVANTAGES:-

• Used for extremely hard material.
• Good machinability for intricate shapes.
• Very low heat production.

LIMITATION:-

Limited for electrically conductive material only .

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FACTORS EFFECTING NON TRADITIONAL MACHINING

FACTORS EFFECTING NON TRADITIONAL MACHINING

THERE ARE VARIOUS FACTORS WHICH EFFECT NON-TRADITIONAL MACHINING.THESE ARE:-

TYPE OF MATERIAL TO BE MACHINED

• Effect of abrasive grain size
• Effect of lubricant
• Effect of temperature
• Tool feed rate
• Effectiveness of machining
• Gap between tool and work piece
• Cost effectiveness

• Effect of lubricant:-

The lubricant used in machining helps ease the machining. The lubricant helps to overcome the high temperature near the machining region by absorbing most of the heat. It also helps to complete the circuit as in case of electro-chemical machining. It acts as electrolyte in this case.
The electrolyte should not have very high fluidity as because it will not stay near machining region. And it should not be very viscous, high viscosity fluid will be unable to carry heat from working region. Hence it should have optimum viscosity.

Various lubricant like Greece, Coconut oil, Mobil etc are used.

• Effect of temperature:-

                                        
The temperature is important factor which effects machinability. When the temperature is very high the machinability decreases as tool may wear out due to high temperature or work piece may get effected resulting in bad machinability.
As the cutting speed increases the temperature increases (as shown in graph), when the speed increases to enormous limit, temperature of machining area also increases to high level, this is to be controlled.

Effect of speed on machining

As the speed increases the machining rate (material removal rate) increases, but up to certain limit only. Beyond a particular limit machinability decreases. High speed results in high temperature generation and also wear of tool may occur.

Effect of grain size

As the speed increases the machining rate (material removal rate) increases, but up to certain limit only. Beyond a particular limit machinability decreases. High speed results in high temperature generation and also wear of tool may occur.

Effectiveness of machine:-

The tool and machine should be such that there should be minimum vibration (in case of ultrasonic machining). The voltage and current should be optimum according to operation requirement. The clamping of work piece to the fixture should be firm enough so that it should not move or deviate while machining.

Gap between tool and work piece:-

The affect of gap between the tool and work piece plays important role in non traditional machining. In case of abrasive jet machining, larger is the gap greater will be the speed of grains due to gravity. similarly in laser beam machining, laser beam penetration will be more if the gap will be less.

Cost effectiveness:-

Production in mass should be such that it is cost effective. There is no use of such production. The process non traditional machining should be chosen that is most cost efficient which further depends on the type of material to be machined and environmental condition. Machining parameter should optimum will affects the cost directly.

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PLASMA ARC MACHINING(PAM),ELECTRON BEAM MACHINING AND ELECTRIC DISCHARGE MACHINING

PLASMA ARC MACHINING (PAM)

what is plasma? 

A Plasma is state of gases which occurs when gases are heated up to very high temperature of approx 5000 degrees. The gases become super heated and ionized (electrically). This can be used to cut metals and other materials.

BASIC IDEA:-
                   
PLASMA ARC MACHINING is the process in which the plasma (super heated gases) at very high velocity is directed on the work piece. This causes deformation of work piece to required shape. The above figure shows basic set up of PAM process.

A tungsten electrode is inserted to the gun and made cathode. Nozzle of the gun is made anode.
Figure below shows tungsten as cathode and nozzle as anode.

Heavy potential difference in developed between cathode and anode to generate plasma.

HEAT GENERATED REGION IN PLASMA ARC MACHINING AS SHOWN IN FIGURE BELOW:-

WORKING PROCESS:-

1. STEP 1

PLASMA GUN:- 

Plasma can be created from many gases like nitrogen, hydrogen, argon etc. The plasma gun has tungsten electrode which is negatively charged and nozzle as positively charged.

High potential difference is applied between them to generate plasma. A strong arc is established between the two terminals anode and cathode. There is a collision between molecules of gas and electrons of the established arc. As a result of this collision gas molecules get ionized and heat is evolved. 

2. STEP 2

This super heated gas is directed towards work piece and such high temperature melts the material easily. Water jacket is provided to cope up with high temperature (to escape the excess heat). 

 
Advantages:-

• Harder and brittle material can be easily cut. 
• Good production rate. 
• Intricate shapes can be machined nicely. 

Disadvantages:-

• Costly process. 
• High heat generation. 

ELECTRON BEAM MACHINING(EBM)


BASIC IDEA :-

As we know that non conventional machining means there is no direct contact between tool and the work piece. In EBM process, high velocity electrons are directed towards the work piece which generates high heat resulting in vaporization of work piece.

WORKING PROCESS:-

VOLTAGE REQUIRED-150-200 KV.
SPEED OF ELECTRONS-200000 m/s.


      

                           fig:-electron beam machining

Electron beam machining as proposed is projection of high velocity electron on work piece which is capable of eroding the material by thermal effect and causing cutting/drilling action.

1. The question may arise in your mind that what is the role of temperature when electron strikes the work piece?
The answer is very simple, when the electron at very high speed (up to 200000 m/s) strikes the work piece,the kinetic energy is converted to thermal energy on impact. This thermal energy is basic reason of melting the work piece.

2. Now you all would be thinking how the electrons achieve such high velocity of 200000 m/s?

A typical EBM gun consists of an electron quot which is generated by a superheated tungsten filament, which also acts as the cathode. A combination of forces from the negative cathode and the attracting forces from the positive anode causes the free electrons to be accelerated and directed toward the work piece. Before passing through the anode, the beam travels through a bias electrode, which controls the flow of electrons and acts as a switch for generating pulses. After passing through the anode, the electron beam is diverging rapidly and traveling at approximately 150000 m/s. A magnetic coil, which functions as a magnetic lens, repels and shapes the electron beam into a converging beam. The beam is then passed through a variable aperture.

By EBM machining we can obtain machining diameter up to 0.025 mm. The vacuum chamber prevents the electrons to get scattered, which may occur due to collision of gas molecule with the electrons. This may reduce the machining efficiency, hence vacuum is provided.

APPLICATIONS:-

• Aircraft engine parts. 
• Intricate and minute holes. 
• Metals such as steel etc can be machined. 

ELECTRIC DISCHARGE MACHINING(EDM)

POINTS TO KNOW:-

• First observation made by Joseph Preistly (1770).
• Consists two electrodes, one as tool and other as work piece with a dielectric medium.
• Material removal is by electric discharge.
• Temperature of spark ranges 8000 degree to 12000 degree Celsius. The spark is very effectively controlled over the surface only.

BASIC IDEA OF EDM:-

It is also a non traditional machining process where machining takes place without direct contact between tool and work piece. EDM is carried by process of electric spark (discharge) between tool and work piece.

There are two electrodes:-
Both the electrodes are aught to be conductive for EDM to take place. Tool electrode is called cathode (steel) Work piece electrode is called anode made up of graphite or copper.


The electrolyte flows between the two electrode. This electrolyte is dielectric fluid which completes the overall circuit.

PROCESS OF EDM:-

The two electrode i.e. tool and work piece is connected with DC pulse supply.
The servo motor is connected to tool head to provide required feed to tool post.
The tool and work piece is separated by di-electric fluid.

USE OF DI ELECTRIC FLUID:-

1. Removes burr (machined particles) from machining area.
2. Removes heat produced due to spark.
3. Act as lubricant.
4. Act as coolent.

When the spark is induced due to potential difference between the electrode, it is directed on work region. The repeated spark generates temperature of 8000-10000 degree Celsius. This temperature can melt any material.

ADVANTAGES:-

• Very intricate shapes can be machined.
• Very hard material can be easily machined.
• Minute holes are drilled.
• Accuracy is high.

DISADVANTAGES:-

• High power consumption.
• Tool wear is problem.
• Slow material removal rate.
• Limitation occurs when work piece is non conductive.

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ABRASIVE JET MACHINING, WATER JET MACHINING AND ULTRASONIC MACHINING

   
ABRASIVE JET MACHINING(AJM)

As explained non traditional machining process involves machining action by indirect contact between tool and work piece. It is a non conventional machining process that performs machining without any contact between tool and work piece.

BASIC IDEA OF ABRASIVE JET MACHINING (AJM)

Abrasive used:-

silicon carbide
aluminium oxide
beads of glass

Diameter of abrasive is about 0.025 mm.

Nozzle made

• Tungsten carbide having life expectancy (12-35 hours).
• synthetic sapphire having life expectancy (up to 300 hours).

Also called as pencil blasting, this process involves projecting high velocity abrasives (silica carbide, aluminium oxide) on the work piece. This high velocity abrasives at speed up to 300 m/s strike the work piece and erodes it. Continuous abrasive action of such abrasives causes continuous deformation of work piece and required shape is obtained.

PROCESS:-

• Highly compressed air or inert gas enters into the filter chamber and impurities are separated. 
• There after it is compressed by compressor up to high pressure (170-1000 kpas). 
• The pressure gauge and flow regulators check the required pressure and flow of air/inert gas. 
• Now the gas enters the mixing chamber, where it gets mixed with abrasives. 
• The required pressure is checked and the mixture enters the nozzle. 
• The nozzle converts the high pressure mixture to high velocity mixture. 
• This high velocity mixture is directed on workpiece and erosion of work material takes place.

ADVANTAGES

• Less heat produced 
• Used for non ductile materials. 
• Good surface finish. 

WATER JET MACHINING

ABRASIVE USED (WATER+GARNET/ALUMINIUM OXIDE)
NOZZLE MADE WITH SINTERED BORIDE

It is another non traditional machining process where there is no contact between tool and the work piece. Water is used as abrasive in such machining .

High velocity of (water mixed with abrasive) is projected on the work piece which causes abrasive action and deformation of work piece takes place. This is basic of water jet machining (WJM).

WATER ALONE CAN BE USED TO CUT SOFT MATERIALS.
BUT WHEN WATER MIXED WITH ABRASIVES IS USED, THIS CAN CUT METALS AND GRANITE ALSO.

                          FIG:-Diagram of WJM

 

 WORKING PROCESS DESCRIPTION

• The water is collected from reservoir by the pump.
• The high pressure pump are capable of producing pressure of 276 MPa to 700 MPa.
• The intensifier and accumulator increases the pressure of the water to the desired limit. Up to (30000-60000 psi).
• The control valve and flow regulator allows desired water to enter the nozzle.

In the nozzle, the abrasive and compressed water is mixed in the nozzle in the mixing chamber. The focusing pipe directs the mixture towards work piece and finally erosion of work piece takes place.

    ULTRASONIC MACHINING               

BASIC PROCESS:-        

• It is process where there is a vibrating tool which oscillates at various frequencies, where further helps to remove material from work piece. This is helped by abrasive slurry which is present between tool and work piece.

ABRASIVE USED

• DIAMOND
• CUBIC BORON NITRIDE  (CBN)
• SILICON CARBIDE
• ALUMINIUM OXIDE

TOOL MATERIALS

Tough and ductile materials are generally used as tool material. Tool material should reduce fatigue failure.

• NICKEL
• SOFT STEELS

SLURRY 

• Water+abrasive
• Oil+abrasive

A abrasive slurry is concentration of water or oil with abrasive material which is present between the work piece and the tool. It occupies a narrow section between the vibrating tool and work piece. The vibrating tool applies force on the abrasive slurry and abrasive having sharp edge in turn applies force on the work piece which erodes the work piece material. It also carries away the eroded material from cutting section and also keeps the temperature low by carrying away heat.

  PROCESS OF MACHINING:-

• The outer source provides power to the transducer and oscillator up to 40 kHz.
• This system provides tool to get directed towards the work piece.

(as the frequency increases the material removal rate increases).

• The amplitude of vibration varies from 0.013 to 0.10 mm.
• The pump sucks the abrasive slurry from reservoir and directs it to cutting action point.

• The high amplitude of vibration or high frequency oscillation creates rapid too and fro motion of tool which pressurizes the abrasive slurry against work piece.
• This causes wear or deformation of work piece.
• Accuracy up to 5 micron can be obtained.
                         

ADVANTAGES:-

• Irregular shapes can be machined.
• Brittle material can be machined
• Good surface finish is obtained.

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CONVENTIONAL AND NON CONVENTIONAL MACHINING DIFFERENCE

CONVENTIONAL AND NON TRADITIONAL MACHINING PROCESS

When we talk about manufacturing process it can be broadly classified as:-

• Primary manufacturing process

• Secondary manufacturing process

Primary manufacturing process includes the basic manufacturing process such as casting, powder metallurgy etc.

Secondary manufacturing process includes removal of material from products obtained from primary manufacturing process (machining). This can also be divided into two parts:-

• Conventional machining process
• Non traditional machining process.

Both the process of machining has some advantage and few disadvantages and suits according to application. In conventional machining process there is direct contact between the work piece and tool. Such process leads to tool wear in good amount due to friction because of direct contact between tool and work piece. The examples are

• Drilling
• Boring
• Grinding
• Cutting
• Broaching
• Lathe operation
• Milling,etc

In non traditional machining process, there is no contact between tool and the work piece. Various other form of energy are used in such processes i.e. indirect energy sources These are used in high strength to weight ratio application. Also used for aerospace and nuclear applications. In short we can say that this type of machining can be performed when complex and intricate shapes is to be obtained. The examples of such process are:-

• Abrasive jet machining (AJM)
• Water jet machining (WJM)
• Ultrasonic jet machining (USM), etc.

BASIC DIFFERENCE BETWEEN CONVENTIONAL AND NON TRADITIONAL MACHINING

1. Conventional machining process

There is direct contact between the tool and work piece.           

fig:-conventional machining

• The cutting action takes place on application of cutting force applied by tool. 
• Under any condition tool is harder than the work piece. 
• Material removal takes place by chip formation by shear deformation (may be microscopic chip formation). 
• Less tool life, due to repeated wear of tool. 
• Any material can be machined. 
• Large amount of noise is produced due to metal and tool contact on cutting. 
• Accuracy is not very high. 
• More care and precaution is aught to be taken for such machining process. 
• Overall cost is less/capital cost is less.
• No need of highly skilled operators.

2.  Non traditional machining

• There is no direct contact between the tool and the work piece. 
• Cutting action takes place by different forms of energy. For example in elecrto chemical machining, chemical reaction is basic process of machining where chemical dissolution of work piece occurs. 
• Tool may or may not be harder than work piece. 
• Material removal may occur by chip formation or by chemical deposition or other form. 
• No noise is produced, since no contact and no friction is involved between tool and work piece. 
• High accuracy is obtained and good surface finish. 
• Tool life is long, since no wear and tear takes place. 
• Skilled labor is to be employed. 
• Costlier process than conventional machining processes.
• This type of machining is helpful in conditions where high temperature rise in work piece during operation is a major problem. In NTM, flow of electrolyte removes heat from working region.
• On the other hand high production rate due to costlier equipment and skilled operators add to its disadvantage.

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