Advanced Manufacturing Nontraditional Machining Processes

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Advanced Manufacturing Nontraditional Machining
Processes
Dr. L. K. Gaafar
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Why Nontraditional Processes?

• New Materials (1940s)
• Stronger
• Tougher
• Harder
• Applications
• Cut tough materials
• Finish complex surface geometry
• Surface finish requirements

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Processes

• Mechanical
• Chemical
• Thermal
• Electrochemical
• Thermoelectric

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Mechanical

• Ultrasonic Machining - Cutting action is
  accomplished with an abrasive slurry which is
  driven by a tool vibrating at high frequency.
  The tool is the exact shape of the desired cut.
• Applications
• slots, blind holes, irregular shapes, and through
  holes.

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Mechanical

• Abrasive Water-Jet Cutting
• Similar to sandblasting
• Process utilizes a high velocity stream of water
  mixed with an abrasive as the cutting tool
• Forces the mixture through a nozzle with a hole
  diameter of .0040 - .012
• System pressures range from 30,000 - 50,000 psi
• Used to cut a variety of materials from wood to
  tool steel
• One disadvantage is that tolerances are typically
  (/- .01)

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Thermal

• Laser
• Laser cutting works by directing the output of a
  high power laser at the material to be cut. The
  material then either melts, burns or vaporizes
  away leaving an edge with a high quality surface
  finish.
• Plasma Cutting
• In this process, an inert gas is blown at high
  speed out of a nozzle at the same time an
  electrical arc is formed through that gas from
  the nozzle to the surface being cut, turning some
  of that gas to plasma. This plasma is
  sufficiently hot to melt the metal and moving
  sufficiently fast to blow molten metal away from
  the cut.

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Chemical

• Chemical Milling
• Controlled etching process
• MRR about .001 cu. in per min .045 cu. in
  hour
• Process
• Sample part is tested for erosion rate
• Part to be chem machined is cleaned
• Mask area you do not want to machine
• Dip part in chemical solution
• hot alkaline

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Electrochemical Machining (ECM)

• Basically the same principle as plating
• Differences
• Part is the anode () and the tool is the cathode
  (-)
• Metal is pulled away from work

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Thermoelectric

• Electrical Discharge Machining (EDM)
• This process is like a mini-thunderstorm.
  Flashes of lightning in rapid succession (500 -
  5,000 sparks per second) erode material from the
  part being machined.

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EDM

• Machining action forms a gap between the part and
  the electrode (tool) which causes a spark which
  removes the material
• Electrode is () and the part is (-)
• Electrodes can be made from
• Brass
• Copper
• Graphite