1. Associate Prof. Mohamed Ahmed Awad
Prepared by
Associate Prof. Mohamed Ahmed Awad
Cairo, 2017

2. Non-traditional Machining Processes
Manufacturing processes can be broadly divided into two groups:
primary manufacturing processes :
Provide basic shape and size
b) secondary manufacturing processes :
Provide final shape and size with tighter control on dimension, surface characteristics 2
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3. Non-traditional Machining Processes
Material removal processes once again can be divided into two groups
Conventional Machining Processes
Non-Traditional Manufacturing Processes or non-conventional Manufacturing processes
Conventional Machining Processes mostly remove material in the form of chips by applying forces on the work material with a wedge shaped cutting tool that is harder than the work material under machining condition. 3
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4. Major characteristics of Traditional Machining Processes
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 4
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5. Major characteristic of Non-traditional Machining Processes
Material removal may occur with chip formation or even no chip formation may take place. For example in AJM, chips are of microscopic size and in case of Electrochemical machining material removal occurs due to electrochemical dissolution at atomic level.
In NTM, there may not be a physical tool present. For example in laser jet machining, machining is carried out by laser beam. However in Electrochemical Machining there is a physical tool that is very much required for machining 5
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6. Major characteristic of Non-traditional Machining Processes
In NTM, the tool need not be harder than the work piece material. For example, in EDM, copper is used as the tool material to machine hardened steels.
Mostly NTM processes do not necessarily use mechanical energy to provide material removal. They use different energy domains to provide machining. For example, in USM, AJM, WJM mechanical energy is used to machine material, whereas in ECM electrochemical dissolution constitutes material removal. 6
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7. 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 workpiece 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. 7
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8. Classification of NTM processes
classification of NTM processes is carried out depending on the nature of energy used for material removal.
1. Mechanical Processes
Abrasive Jet Machining (AJM)
Water Jet Machining (WJM)
Ultrasonic Machining (USM)
2. Electrochemical Processes
Electrochemical Machining (ECM)
Electro Chemical Grinding (ECG)
3. Electro-Thermal Processes
Electro-discharge machining (EDM)
Laser Jet Machining (LJM)
Electron Beam Machining (EBM)
4. Chemical Processes
Chemical Milling (CHM) 8
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1- Mechanical Process 9
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10. 2- Electrochemical Process10
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11. 3. Electro thermal Process11
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4. Chemical Process 12
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13. Mechanical Processes

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1- Mechanical Process
Abrasive jet machining (AJM).
Water jet machining (WJM).
Ultrasonic machining (USM). 14
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15. Abrasive Jet machining (AJM)15
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Abrasive Grinding
Can be viewed as multiple very small cutting edges
Results in a very fine finish
Can leave residual stresses
Slow, small material removal rates
Sparking out 16
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In Abrasive Jet Machining (AJM), abrasive particles are made to impinge on the work material at a high velocity. The high velocity abrasive particles remove the material by micro-cutting action as well as brittle fracture of the work material.
In AJM, generally, the abrasive particles of around 50 μm grit size would impinge on the work material at velocity of 200 m/s from a nozzle of I.D. of 0.5 mm with a stand off distance of around 2 mm. The kinetic energy of the abrasive particles would be sufficient to provide material removal due to brittle fracture of the work piece or even micro cutting by the abrasives 19
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20. Abrasive Jet Machining Parameters
Process Parameters and Machining Characteristics
Abrasive : Material – Al2O3 / SiC
Shape – irregular / spherical
Size – 10 ~ 50 μm
Mass flow rate – 2 ~ 20 gm/min
Carrier gas : Composition – Air, CO2, N2
Density – Air ~ 1.3 kg/m3
Velocity – 500 ~ 700 m/s
Pressure – 2 ~ 10 bar
Flow rate – 5 ~ 30 lpm
Abrasive Jet : Velocity – 100 ~ 300 m/s
Mixing ratio – mass flow ratio of abrasive to gas
Stand-off distance – 0.5 ~ 5 mm
Impingement Angle – 600 ~ 900
Nozzle : Material – WC
Diameter – (Internal) 0.2 ~ 0.8 mm
Life – 10 ~ 300 hours 20
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21. Abrasive Jet Machining
Abrasive Jet Machining
effect of process parameters on MRR 21
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22. Abrasive Jet Machining
Abrasive Jet Machining 22
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24. Water Jet machining (WJM)

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In water-jet machining (WJM), a considerable concentrated force resulted from the momentum change of the stream is acting on the workpiece.
This force is utilized in cutting and deburring operations.
The water jet acts like a saw and cuts a narrow groove in the material.
A pressure level of about 400 MPa is generally used for efficient operation. Jet-nozzle diameters usually range between 0.05 mm and 1 mm. 25
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Water Jet machining 26
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Water Jet examples 27
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29. Water Jet and Abrasive Water Jet Machining29
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30. Water Jet and Abrasive Water Jet Machining
WJM - Pure
WJM - with stabilizer
AWJM – entrained – three phase –
abrasive, water and air
AWJM – suspended – two phase –
abrasive and water
o Direct pumping
o Indirect pumping
o Bypass pumping 30
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31. Waterjet and Abrasive Waterjet (AWJ) Cutting31
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Abrasive Waterjet and Waterjet examples 32
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33. Water Jet and Abrasive Water Jet Machining
Advantages of AWJM
• Extremely fast set-up and programming
• Very little fixturing for most parts
• Machine virtually any 2D shape on any material
• Very low side forces during the machining
• Almost no heat generated on the part
• Machine thick plates 33
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Components of AWJM 34
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Components of AWJM
Catcher
(a) water basin
(c) catcher plates (TiB2)
(b) steel/WC/ceramic balls 35
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36. Ultrasonic machining (USM)

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Ultrasonic machining is used to machine very hard and brittle materials like tungsten carbides and ceramics which are difficult to machine by conventional methods.
The term ultrasonic is used to describe a vibratory wave with frequency above human ear upper frequency limit. The tool is the exact shape of the desired shape to be cut into the work.
The tool is made to oscillate or vibrate at high frequency (15,000 to 22,000 Hz), in a direction normal to the surface being machined. 37
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Metal removal is accomplished by the repeated hammering action of the abrasive particle into the workpiece by the tool. The hard work material is broken into pieces by this method. 38
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Ultrasonic Machining 39
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Ultrasonic Machining
Ultrasonic vibration (20,000 Hz) of very small amplitudes ( mm) drive the form tool (sonotrode) of ductile material (usually soft steel)
An abrasive slurry is flowed through the work area
The workpiece is brittle in nature (i.e. glass)
The workpiece is gradually eroded away. 40
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42. Electro – Chemical machining (ECM)

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Electrochemical machining is basically the reverse of electroplating.
An electrolyte acts as current carrier, and the high rate of electrolyte movement in the tool-workpiece gab washes metal ions away from the workpiece (anode) before they have a chance to plate onto the tool (cathode).
The cavity produced is the female mating image of the tool. 43
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Chemical Machining
Applications:
Aerospace industry
Engraving
Circuit boards
A maskant is applied over areas you don’t want to machine
Photochemical methods
Apply maskant to entire surface and use laser to cut 46
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47. Chemical Machining (Chemilling)
Place the entire part in a chemical bath (acid or alkali depending upon the metal)
Control temperature and time of exposure to control material removal 47
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48. Electro-Chemical Machining (ECM)48
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49. Electro-Chemical Machining (ECM)
Works on the principle of electrolysis – accelerated chemilling
Die is progressively lowered into workpiece as workpiece is dissociated into ions by electrolysis
Electrolytic fluid flows around workpiece to remove ions and maintain electrical current path
Low DC voltage, very High current (700 amps) 49
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50. Electrochemical grinding
Combines electrochemical machining with conventional grinding
Grinding wheel is the cathode
Metal bonded wheel with diamond or Al2O3 abrasive
Majority of material removal from electrolytic action (95%) therefore very low wheel wear
Much faster than conventional grinding 50
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51. Electro – Discharge machining (EDM)

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A spark is directed toward a metal in a liquid
The spark melts the metal.
When the spark stops, the melted part in the liquid is cooled rapidly and scatters intensely.
The remaining portion is depressed like a hole, and it looks like a crater of the moon. 52
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53. Electrode Discharge Machining (EDM)53
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54. Electrode Discharge Machining (EDM)
Direct Competitor of ECM – much more common than ECM
The tool acts as a cathode (typically graphite) is immersed in a Dielectric fluid with conductive workpiece
DC voltage (~300V) is applied. As voltage builds up over gap between workpiece and tool, eventually you get dielectric breakdown (sparking at around 12,000 deg F)
The sparking erodes the workpiece in the shape of the tool
The tool is progressively lowered by CNC as the workpiece erodes
Cycle is repeated at 200, ,000 Hz
Dielectric:
Cools tool and workpiece
Flushes out debris from work area 54
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Die Sinker
Die sinker EDM
The die sinks into the part as it sparks away the workpiece
Most common Injection molding die process 55
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Die Sinker vs. Wire EDM
Wire EDM
The electrode is a wire that traverses through the part
Common for Extrusion Dies 56
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57. Laser beam machining (LBM)

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In laser-beam machining (LBM), the source of energy is a laser (Light Amplification by Stimulated emission of radiation), which focuses optical energy on the surface of the workpiece,
Laser provides unidirectional beam of light. Focusing a laser beam on a small spot resulting in high density energy enough to melts and evaporates any known material with any strength in a controlled manner. 58
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Laser Beam Machining
Lasers are high intensity focused light sources
CO2
Most widely used
Generally more powerful that YAG lasers
Cutting operations commonly
Nd:YAG (Neodymium ions in an Yttrium Aluminum Garnet)
Less powerful
Etching/marking type operations more commonly 59
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Laser Beam Machining
Limited in depth of cut (focus of light)
Would limit workpiece to less than 1 inch (< ½” typically) 60
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61. Plasma arc machining (ECM)

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Plasma is a state of material when the gases are heated to elevated temperature above 3000 ºC. The gases turn into a distinctly different type of a matter which is plasma. The metal removal is basically due to the high temperature produced (11000 to ºC ). 62
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Plasma arc process is used to cut aluminum and other nonferrous materials.
Plasma machining is mainly used to cut stainless steel.
Cutting speed is between 50 to 6000 mm/min. Roughness of the cut surface is between 1.6 to 3.2 µm 64
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65. Chemical Machining (CHM)

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In chemical machining process, material is removed by the attack of chemical reagent on selective different areas of the workpiece surface.
The attacked area is controlled by a removable layers of material, called masking. The Masking material is commonly in the form of tapes or paints. 66
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The masking that covers various regions that require etching is then peeled off by the scribe-and-peel technique.
The exposed surfaces are etched.
Common etchants are sodium hydroxide for aluminum, solutions of hydrochloric and nitric acids for steels, and iron chloride for stainless steels. 67
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Comparisons 69
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Comparisons 70
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