advanced and hybrid machining process

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Non Traditional Machining Processes

• 
  Presented By
• 
  Yashpal Maru (111133)
• Sitesh
  (111209)
• 
  Karan Sharma (111616)
• 
  Abhilash(111671)
• 
  Ankit lal (111672)
• 
  Anshu(111753)
• 
  Sonu Meena(111865)

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The Need for Advanced Machining Processes

• Traditional machining processes
• Material removal by mechanical means, such as
  chip forming, abrasion, or micro-chipping
• Advanced machining processes
• Utilize chemical, electrical, and high-energy
  beams
• The following cannot be done by traditional
  processes
• Work piece strength and hardness very high,
  gt400HB
• Work piece material too brittle, glass, ceramics,
  heat-treated alloys
• Work piece too slender and flexible, hard to
  clamp
• Part shape complex, long and small hole
• Special surface and dimensional tolerance
  requirements

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Development

• Development of harder and difficult to machine
  materials such as hast alloy, nitra alloy,
  waspalloy, nimonics, carbides, stainless steel,
  heat resisting steels and many other HSTR alloys
• Used in aerospace industry, nuclear engineering
  and other industries owing to their high strength
  to weight ratio, hardness and heat resisting
  quality.

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CHIPS FORMATION IN CONVENTIONAL MACHINING PROCESS
CHIP
TOOL
WORKPIECE
Thus the major characteristics of conventional
machining are Generally macroscopic chip
formation by shear deformation Material
removal takes place due to application of cutting
forces energy domain can be classified as
mechanical Cutting tool is harder than work
piece at room temperature as well as under
machining conditions TOOL WORKPIECE CHIP
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Schematic representation of various metal cutting
operations.
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The broad classification is given as follows

• Thus classification of NTM processes is carried
  out depending on the nature of energy used for
  material removal.
• Mechanical Processes
• ? Abrasive Jet Machining (AJM)
• ? Ultrasonic Machining (USM)
• ? Abrasive Water Jet Machining (AWJM)
• Electrochemical Processes
• ? Electrochemical Machining (ECM)
• ? Electro Chemical Grinding (ECG)
• ? Electro Jet Drilling (EJD)

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• Electro-Thermal Processes
• ? Electro-discharge machining (EDM)
• ? Laser Beam Machining (LBM)
• ? Electron Beam Machining (EBM)
• Chemical Processes
• ? Chemical Milling (CHM)
• ? Photochemical Milling (PCM) etc.

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Abrasive Jet Machining (AJM)
Abrasive feeder
filter
Pressure control valve
exhaust
Mixing chamber
Drier
Nozzle
¼ turn valve
Electro-magnetic shaker
Air compressor
work piece
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LASER Beam Machining (LBM)
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Electron Beam Machining (EBM)
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Chemical Machining (CHM)
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PAM
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ELECTROCHEMICAL MACHINING (ECM)
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• Combines chemical attack and electrical attack
• High material removal rate
• Masking is used to control attack
• Conforming electrodes are to control shape
• Commonly used for aircraft parts such as airfoil
  shapes
• Normally followed by abrasive finishing or laser
  peening to remove partially adhering particles
• Works with a wide variety of metals

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Electrolyte

• An electrolyte is any substance containing
  free ions that make the substance electrically
  conductive. The most typical electrolyte is
  an ionic solution, but molten electrolytes
  and solid electrolytes are also possible.
• Function of electrolyte-
• Carrying current between tool and work peice
• Remove products of machining and other insoluble
  products from cutting region
• Dissipate heat produced in the operation.
• Maintain a constant temperature in the machining
  region
• Electrolyte used- Sodium chloride, Sodium
  Nitrate, Sodium Hydroxide

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Characteristics of Electrolyte

• Good electrical conductivity
• Non toxicity and chemical stability
• Non corrosive property
• Low viscosity and high specific heat
• inexpensive and easily available
• Avoid the formation of a passive film on the
  anodic surface.
• Not deposit on the cathode surface, so that the
  cathode shape remains unchanged
• Maintain its stable ingredients and pH value,
  during the machining period

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Advantages of ECM

• There is no wear in the tool because there is no
  contact between the tool and the workpiece.
• Machining is done at low voltages, compared to
  other processes, with high metal removal rates.
• Very small dimensions up to 0.05 mm can be
  controlled.
• Complicated profiles can be machined easily in a
  single operation
• Because of the low temperature developed, no
  thermal damage occurs to the workpiece structure.
• Hard conductive materials can be machined
• The surface finish can be maintained at 0.1 to
  1.25 µm Ra.
• Because of its high capital cost, ECM is only
  suitable for mass production work.

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Disadvantages

• A huge amount of energy is consumed (about 100
  times that required
• for turning or drilling steel).
• Metal removal rates are slow compared with
  conventional methods.
• ECM can only be applied to electrically
  conductive workpiece materials.
• There are difficulties in safely removing and
  disposing of the explosive
• hydrogen gas generated during machining.
• The workpiece needs to be cleaned and oiled
  immediately after
• machining.

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• There are difficulties with handling and
  containing the electrolyte, which may attack the
  equipment.
• It is not easy to duplicate the shape of the tool
  electrode in the workpiece with a high degree of
  accuracy because of the side machining effect.
• The process cant produce sharp internal or
  external edges.
• The pumping of high-pressure electrolyte into the
  narrow machining
• gap gives rise to large forces acting on
  the tool and the workpiece.

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Ultrasonic Machining (USM)
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Electric Discharge Machining (EDM)

• Successive electric arcs melt tiny droplets from
  surface of workpiece
• Frozen droplets must be flushed away
• Electrodes are made from graphite, copper or
  copper-tungsten alloy
• Material removed from electrode by arc
• Recast layer of approximately 0.001 in depth
  left on surface
• Secondary process such as chemical machining used
  to remove recast layer

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Dielectric Fluid

• A dielectric is an electrical insulator that can
  be ionized by an applied electric field. When a
  dielectric is placed in an electric field,
  electric charges do not flow through the material
  as they do in a conductor, but only slightly
  shift from their average equilibrium positions
  causing dielectric polarization.
• Characteristic-
• Low viscosity
• High fluidity
• Controlled level of toxicity
• Cheap and easily available

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Function of Dielectric Fluid

• Insulation Until required breakdown voltage
  attained.
• Should act as conductor after required breakdown
  voltage attained.
• Should demonize rapidly after the discharge has
  been occurred.
• Clean spark gap by carrying away the molten
  metal.
• Should cool the tool work piece and spark region.
• Dielectric Used-
• light hydro carbon oil, kerosene,
  paraffin, transformer oil, try ethylene glycol.

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Difference between EDM ECM

1. Uses dielectric fluid as a conducting medium
   between tool and work piece.
2. Wear of tool takes place during the process.
3. Heat is generated during the process.
4. Low metal removal rate.
5. It works on the principle of spark erosion.
6. Metal is removed by melting and vaporization.
7. Tools used are oversize for machining inside
   surfaces and undersize for machining outside
   surfaces.

1. Using electrolyte as a conducting medium between
   tool and work piece.
2. No wear of tool during process so tool life is
   high.
3. No heat is generated during the process.
4. Metal removal rate is high.
5. It works on principle of Faradays law of
   electrolysis.
6. Metal is removed by electrochemical reaction.
7. Tool used are of required size of the work piece.

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Dielectric Electrolyte

1. It is used as conducting medium in EDM process.
2. It act as conductor and insulator both.
3. Tool wear takes place in the dielectric fluid.
4. It may or may not be corrosive in nature.

1. It used as conducting medium in ECM process.
2. It always provide passage for supply of
   electricity.
3. The electrolyte selected is such that there is no
   wear of tool.
4. It should be non corrosive in nature.

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Economics of Advanced Machining Processes

• High cost of equipment, which typically includes
  computer control
• May use hard tooling, soft tooling, or both
• Low production rates
• Can be used with difficult-to-machine materials
• Highly repeatable
• Typically requires highly skilled operators

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HYBRID MACHINING Process
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HYBRID MACHINING PROCESS

• Hybrid machining is a manufacturer of fastener
  machinery to make a single product out of two
  operations or two different raw materials.
• Reasons for developing this process are to make
  use of the combined or mutually enhanced
  advantages, and to avoid or reduce adverse
  effects.
• Example Biometals rivets.

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METHODOLOGY FOR HYBRID MACHINING

• Processes in which all constituents processes are
  directly involved in material removal.
• Processes in which only one of the participating
  processes directly removes the material while the
  other only assist in removal by changing the
  conditions of machining in a positive direction
  from the point of view of improving capabilities
  of machining.

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PROCESSES AND THEIR INTERACTIONS

• Different kind of machining process based on
  different kind of interaction for improving
  manufacturing characterstics of shaping and
  finishining process.
• Thermal interaction
• Mechanical interaction
• Chemical interaction and
• Electro-chemical interaction

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TYPES OF HMP

• Abrassive electro-chemical grinding,
• Abrassive electro-chemical honing,
• Electro-chemical discharge machining,
• Electro-chemical arc machining,
• Laser electro-chemical machining,
• Abrassive electrical discharge machining,
• Ultrasonic machining
• Magnetic abrassive machining

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ELECTROCHEMICAL DISCHARGE MACHINING
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PRINCIPLE OF WORKING

• ECM-Anodic dissolution of work
• EDM-Spark erosion
• ECDM-Anodic dissolution Spark erosion
• Electro chemical reaction
• Passivating film
• Spark erosion

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EQUIPMENT

• Voltage-40-200V,DC
• Current-3-4A
• Electrolyte-semi dielectric fluids
• Electrode gap-.01-1micro meters
• 3D tool feeder

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WORKING

• Anodic dissolution
• Passivating film formation
• Spark errosion

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TOOL PROPERTIES

• High electrical conductivity
• High themal conductivity
• High melting point
• Cheapness
• High machinability
• Egcu,chisel steel,graphite,etc.

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FUNCTIONS OF
ELECTROLYTE

• Maintain constant resistance accross the gap
• Cools the spark region
• Removes erroded particles
• Aviod welding of tool and work
• Egaqu solution of KOH,sodium silicate,sodium
  nitrate,etc

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TOOL WEAR

• FACTORS AFFECTING TW
• 1.Diameter of tool
• 2.Voltage
• 3.Capacity
• 4.Liquid density
• w 1.329 10 -11 D -1.27 U 5.739 C 0.36
  d 9.655

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COMPARISON
ASPECTS ECM EDM ECDM
PRINCIPLE Anodic dissolution Spark errossion Both
POWER 10,000A,2-3V,DC 200A,50-200V,DC 3-4A,40V,DC
WORK PIECE conductive conductive Conductivenon conductive
MRR less less 5times faster than EDM
TOOL WEAR Lessthan both Higher than ECDM Lessthan EDM
ACCURACY Higherthan EDM Dimensional acc-.03mm -.01mm
SURFACE FINISH Higher than both less Higher than EDM
COST Less initial than ECDM Less initial than ECDM high
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ADVANTAGES

• High accuracy
• Method does not leave any chips or burrs
• High surface finish
• Less power consumption
• Does not need skilled operators
• Machine conducting and non concucting

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DISADVANTAGES

• Low mrr
• Electrode wear
• High initial cost
• Thickness of ceramic material can be machined is
  limited to 1.5mm
• Radial over cut

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applications

• ECDG
• ECDD

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CONCLUSION

• It utilizes both the advantages of ECM EDM
• The applied voltage,electrotyte
  cocetration,elecrode gap are affect the MRR
• The applied voltage,dia of tool,density,capacity
  are affect the tool wear

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THANK YOU