PPT on Unconventional machining process

CORE JAVAPresented On :- Unconventional Machining Process

Presented By :- ANAND KUMAR (ME/13/710)

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Outline

AJM LBM EDM USM EBM ECM

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Machining Process Manufacturing processes can be broadly divided into

two groups:a) Primary manufacturing processes : Provide basic

shape and sizeb) Secondary manufacturing processes : Provide final

shape and size with tighter control on dimension, surface characteristics

Material removal processes once again can be divided into two groups

1. Conventional Machining Processes 2. Non-Traditional Manufacturing Processes or non-

conventional Manufacturing processes

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Classification 1. Mechanical Processes • Abrasive Jet Machining (AJM) • Ultrasonic Machining (USM) • Water Jet Machining (WJM) • Abrasive Water Jet Machining (AWJM) 2. Electrochemical Processes • Electrochemical Machining (ECM) • Electro Chemical Grinding (ECG) • Electro Jet Drilling (EJD) 3. Electro-Thermal Processes • Electro-discharge machining (EDM)• Laser Jet Machining (LJM) • Electron Beam Machining (EBM) 4. Chemical Processes• Chemical Milling (CHM) • Photochemical Milling (PCM)

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Needs for Non Traditional Machining• Extremely hard and brittle materials or Difficult to

machine materials are difficult to machine by traditional machining processes.

• When the work piece is too flexible or slender to support the cutting or grinding forces.

• When the shape of the part is too complex.• Intricate shaped blind hole – e.g. square hole of 15

mmx15 mm with a depth of 30 mm • Deep hole with small hole diameter – e.g. φ 1.5 mm

hole with l/d = 20 • Machining of composites.

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Conventional Machining VS Unconventional Machining

In Conventional machining process, the cutting tool and work piece are always in physical contact, with a relative motion against each other, which results in friction and a significant tool wear.

In Unconventional machining processes, there is no physical contact between the tool and work piece. Although in some non-traditional processes tool wear exists, it rarely is a significant problem.

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Outline of AJM

Definition Schematic Diagram of AJM Typical AJM parameters Applications Limitations Advantages Disadvantages Video of Cutting Process

Definition of AJM :-

In AJM, the material removal takes place due to impingement of the fine abrasive particles. These particles move with the high speed air (or gas) stream.

The abrasive particles are typically of 0.025 mm diameter and the air discharges at a pressure of several atmosphere.

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Schematic Diagram of AJM

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Aluminum oxideBoron NitrideDiamond Dust

Dry

air,

nitr

ogen

or c

o2

Working of Abrasive jet machining: (AJM):

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The nozzle is made of a hard material like Tungsten Carbide here fine grained abrasive particles are fed from the Hooper into the mixing chamber.

High pressure air is forced in to the mixing chamber.

The stream of abrasive particles bombards the work piece at a very high speed and removes the work material due to erosion.

The abrasive particle feed rate is controlled by the amplitude of vibration of the mixing chamber.

Typical AJM Parameters

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Abrasive Aluminum oxide for Al and Brass. SiC for Stainless steel and Ceramic Bicarbonate of soda for Teflon Glass bed for polishing.

Size 10-15 Micron

Quantity 5-15 liter/min for fine work 10-30 liter/min for usual cuts. 50-100 liter/min for rough cuts


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Medium Dry air, CO2, N2 Quantity: 30 liter/min Velocity: 150-300 m/min Pressure: 200-1300 KPa

Nozzle Material: Tungsten carbide Stand of distance: 2.54-75 mm Diameter: 0.13-1.2 mm Operating Angle: 60° to vertical


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Factors affecting MRR: Types of abrasive and abrasive grain size Flow rate Stand off distance Nozzle Pressure

Nozzle

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The nozzle is one of the most vital elements controlling the process characteristics. Since it is continuously in contact with the abrasive grains flowing at a high speed, the material must be hard to avoid any significant wear.

One of the most important factors in AJM is the distance between the work surface and the tip of the nozzle, normally called the nozzle distance

Nozzle Tip Distance

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Applications:-

For drilling holes of intricate shapes in hard and brittle materials

For machining fragile, brittle and heat sensitive materials.

AJM can be used for drilling, cutting, deburring, cleaning and etching.

Micro-machining of brittle materials

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Limitations:-

MRR (Material removal rate) is rather low (around ~ 15 mm^3/min for machining glass).

Abrasive particles tend to get embedded particularly if the work material is ductile.

Tapering occurs due to flaring of the jet. Environmental load is rather high.

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Advantages:-

Extremely fast setup and programming. No start hole required. There is only one tool. Low capital cost. Less vibration. No heat generation in work piece. Environmentally Friendly.

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Disadvantages:-

Low metal removal rate. Abrasive powder cannot be reused. Tapper is also a problem.

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Video of cutting process

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Any Questions ???

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Outline of LBM

Definition Schematic Diagram of LBM Working of LBM Applications Limitations Advantages Disadvantages Video of Cutting Process

Definition of LBM :-

Laser-beam machining is a thermal material-removal process that utilizes a high-energy, coherent light beam to melt and vaporize particles on the surface of metallic and non-metallic work pieces.

Lasers can be used to cut, drill, weld and mark. LBM is particularly suitable for making accurately placed holes.

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Principle of Laser beam machining (LBM):

Conversion of electrical energy into heat energy to emit laser beam energy.

Laser beam is focused on lance then create high energy the high energy concentration on work piece then work piece is melt and vaporized of metal.

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Working of LBM

The diagram of LBM is shown in figure.

Laser is stand for Light Amplification by Simulated Emulsion of Radiation.

The work piece is placed on the aluminum work table which material is hard not cut by laser beam.

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Working of LBM

Ruby rod is used into form of cylindrical crystal both ends of ruby rod are finished to optical tolerance.

The flash lamp wound around the ruby rod and connected to power supply.


Working of Laser beam machining (LBM):

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The ruby rod becomes high efficient on low temperature and low efficient on high temperature. It is thus continuous cooled with water, air or liquid nitrogen.

When the light beam has been amplified sufficiently and intensity beam of light comes out form partially reflected end it is focused on the work piece at the focused very high temperature which vaporized and removes the metal on work piece.

Applications:-

LBM can make very accurate holes as small as 0.005 mm in refractory metals ceramics, and composite material without warping the work pieces.

It is used for welding of thin metal sheet. Leaser can be used for cutting as well as drilling. Heat treatment. It is used for cutting complex profile.

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Limitations:-

Uneconomic on high volumes compared to stamping

Limitations on thickness due to taper High capital cost High maintenance cost Assist or cover gas required

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Advantages:- Very hard and abrasive material can be cut. Sticky materials are also can be cut by this

process. It is a cost effective and flexible process. High accuracy parts can be machined. No cutting lubricants required No tool wear Narrow heat effected zone No contact between tool and work piece.

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Disadvantages:-

Investment cost is more. Skilled operator is required. Operating cost is more. Flash lamp life is too short.

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Summary:-

Mechanics of material removal : Melting, Vaporization Medium : Normal atmosphere Tool : Higher power laser beam Maximum material removal rate: 5 mm^3/min Specific power consumption : 1000 W/mm^3/min Materials application : All materials Shape application : Drilling fine holes Limitations : Very power consumption, cannot cut

materials with high heat conductivity and high reflectivity

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Video of Cutting process

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Video of Cutting process

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Any Questions ???

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Outline of EDM

Definition Schematic Diagram of EDM Working of EDM Applications Advantages Disadvantages Video of Cutting Process

Principle of EDM:

Electrical discharge machining (EDM), sometimes also referred to as spark machining, spark eroding, burning, die sinking, wire burning or wire erosion, is a manufacturing process whereby a desired shape is obtained using electrical discharges (sparks).

Material is removed from the work piece by a series of rapidly recurring current discharges between two electrodes , separated by a die-electric liquid and subject to an electric voltage. One of the electrodes is called the tool-electrode, or simply the "tool" or "electrode", while the other is called the workpiece-electrode, or "workpiece".

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Working of EDM

The diagram of electro discharge machining shown in figure.

EDM is thermal erosion process whereby material is melted and vaporized from an electrically conductive work piece immerse in a liquid dielectric with a series of spark discharge between the tool electrode and the work piece created by a power supply.


Working of EDM

The electrode and the work piece are separated by a dielectric medium.

The dielectric medium is like as kerosene, paraffin or light oil.

The strong electrostatic field between the electrode and work piece produce emission of electrons from the cathode.


Working of EDM

In this gap between tool and work piece get ionized. The liquid is force to sparking zone.

Due to high temperature, the metal at the sparking zone melts instantaneously.

The material of the tool is usually a material which conduct electricity and which can be easily shaped.


Advantages:- Smaller holes can be easy machined. No contact between tool and work piece then

tool life is increase. Any complex shape can be machined.

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Disadvantages:-

Tool life is not longer. Power consumption is high. Cycle time is more

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Summary:-

Mechanics of material removal : Electrolysis Medium : Conducting electrolyte Tool : Cu, Brass, Steel Gap : 50-300 µm Maximum material removal rate: 15*10^3 mm^3/min Specific power consumption : 7 W/mm^3/min Materials application : All conducting metals and alloys Shape application : Blind complex cavities, curved

surfaces, through cutting, large through cavities Limitations : High speed energy consumption, not

applicable with electricity non-conducting materials

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Video


Any Questions ???

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Outline of USM

Definition Schematic Diagram & working of USM Applications Advantages Disadvantages Summary Video

Principle of Ultrasonic machining(USM):

In this method with the help of piezoelectric transducer tool is vibrate at high frequency in a direction normal to the surface being machined abrasive slurry are used for the remove the metal from work piece.

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Working of USM

The USM diagram shown in figure.

In ultrasonic machining a tool vibrate longitudinally at 20 to 30 kHz with amplitude between 0.01 to 0.06 mm is pressed on to the work surface with light force.

The electronic oscillator and amplifier is also known as generator.


Working of USM

It converts the electrical energy of low frequency to high frequency.

At the time high frequency current is passed through the coil therefore change in electromagnetic field which produces longitudinal strain.


Working of USM

As the tool vibrate with specific frequency the abrasive slurry mix with water and grain of definite proportion is made to flow under pressure through the tool work piece interface. The flow of slurry through the work tool interface actually causes thousand of microscopic grain to remove the work material by abrasion.

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Applications:-

USM is best suitable for hard, brittle material, such as ceramics, carbides, glass, precious stone etc.

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Advantages:- Any materials can be machined regardless of

their electrical conductivity. Especially suitable for machining of brittle

materials. Machined parts by USM possess better surface

finish and higher structural integrity. USM does not produce thermal, electrical and

chemical abnormal surface.

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Disadvantages:-

Tool wears fast in USM. Machining area and depth is restraint in USM. High cost of tooling. MMR is low.

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Summary:- Mechanics of material removal : Brittle fracture caused by

impact of abrasive grains due to tool vibrating at high frequency. Medium : Slurry Tool : Soft Steel Gap : 25-40 µm Frequency : 15-30kHz Amplitude : 25-100 µm Specific power consumption : 1000 W/mm^3/min Materials application : Metals and alloys, semiconductors, non-

metals Shape application : Round and irregular holes Limitations : Very low mrr, tool wear, depth of holes and cavities

small

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Video


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Outline

Definition Schematic Diagram of EBM Working of EBM Applications Limitations Advantages Video of Cutting Process

Definition of EBM :-

Electron Beam Machining (EBM) is a thermal process. Here a steam of high speed electrons impinges on the work surface so that the kinetic energy of electrons is transferred to work producing intense heating.

Depending upon the intensity of heating the work piece can melt and vaporize.

The process of heating by electron beam is used for annealing, welding or metal removal.

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EBM:

During EBM process very high velocities can be obtained by using enough voltage of 1,50,000 V can produce velocity of 228,478 km/sec and it is focused on 10 – 200 μM diameter.

Power density can go up to 6500 billion W/sq.mm. Such a power density can vaporize any substance immediately.

Complex contours can be easily machined by maneuvering the electron beam using magnetic deflection coils

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EBM:

To avoid a collision of the accelerating electrons with the air molecules, the process has to be conducted in vacuum. So EBM is not suitable for large work pieces.

Process is accomplished with vacuum so no possibility of contamination.

No effects on work piece because about 25-50μm away from machining spot remains at room temperature and so no effects of high temperature on work

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Working of EBM

The EBM beam is operated in pulse mode.

This is achieved by appropriately biasing the biased grid located just after the cathode.

Switching pulses are given to the bias grid so as to achieve pulse duration of as low as 50 μs to as long as 15 ms.


Working of EBM

Beam current is directly related to the number of electrons emitted by the cathode or available in the beam.

Beam current once again can be as low as 200μ amp to 1 amp. Increasing the beam current directly increases the energy per pulse.


Working of EBM

Similarly increase in pulse duration also enhances energy per pulse.

High-energy pulses (in excess of 100 J/pulse) can machine larger holes on thicker plates.

A higher energy density, i.e., for a lower spot size, the material removal would be faster though the size of the hole would be smaller.

The plane of focusing would be on the surface of the work piece or just below the surface of the work piece.

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Applications:-

Used for producing very small size holes like holes in diesel injection nozzles, Air brakes etc.

Used only for circular holes.

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Limitations:-

Material removal rate is very low compared to other convectional machining processes.

Maintaining perfect vacuum is very difficult. The machining process can’t be seen by

operator. Work piece material should be electrically

conducting.

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Advantages:- Very small size holes can be produced. Surface finish produced is good. Highly reactive metals like Al and Mg can be

machined very easily.

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Summary:-

Mechanics of material removal : Melting, Vaporization Medium : Vacuum Tool : Beam of electron moving at very high velocity Maximum material removal rate: 10 mm^3/min Specific power consumption : 450 W/mm^3/min Materials application : All materials Shape application : Drilling fine holes, cutting contours in

sheets, cutting narrow slots Limitations : Very high specific energy consumption,

necessity of vacuum, expensive machine

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Video


Any Questions ???

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CORE JAVATHANK YOU

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PPT on Unconventional machining process