2. Chemical Machining
Etching:
Chemical reaction between reagent (in gas, solution, or paste form)
and workpiece.
Main uses:
- Shallow, wide cavities on plates, forgings, castings reduce weight
- Electronics manufacturing (wafer fabrication)
- Hydrogen Flouride, Hydrofloric acid: etching of glass
3. Photo-Chemical Machining
Main uses:
- Flat springs, metal bookmarks, encoder wheels, lead frames for IC chips,
sieves for medical applications, microwave oven filters, heat-sinks for PCBs
(i) Clean (ii) Apply resist (iii) UV exposure (iv) Development (v) Etching (v) Stripping
(i) Clean (ii) Apply resist (iii) UV exposure (iv) Development (v) Etching (v) Stripping
4. Electrochemical Machining (ECM)
Reverse of electro-plating (workpiece is anode)
Main uses:
- Dies and glass-making molds, turbine and compressor blades, Holes, Deburring
Due to low forces on tool,
ECM can be used to make
holes at very large angle to
a surface – an example is
shown in the turbine nozzle
holes in the figure here.
[source: www.barber-nichols.com]
Due to low forces on tool,
ECM can be used to make
holes at very large angle to
a surface – an example is
shown in the turbine nozzle
holes in the figure here.
[source: www.barber-nichols.com]
5. Electro-Discharge Machining (EDM)
[source: iprod.auc.dk]
- Sparks between electrode-workpiece
- Dielectric flushes the metal powder
- Inexpensive, precise, complex shapes
- Workpiece must be a conductor
[source: www.magnix.co.kr]
Electrode EDM
Wire-cut EDM
6. Laser cutting
Light Amplification by Stimulated Emission of Radiation
- High energy density (small focus area)
- Uses: Cutting, welding, precision holes
- Common lasers: CO2, Nd:YAG
- Continuous power or Pulsed (more precise)
Nd:YAG laser cut:
larger dia and
heat-affected zone
Femtosecond laser cut:
smaller diameter,
lower thermal damage
Microscope image of laser cut hole
Nd:YAG laser cut:
larger dia and
heat-affected zone
Femtosecond laser cut:
smaller diameter,
lower thermal damage
Microscope image of laser cut hole
7. Ultrasonic Machining
~
power
supply
Nozzle Abrasive
slurry
Transducer
Up-down vibration of tool
hammers the abrasive particles
against workpiece, causing cutting
~
power
supply
Nozzle Abrasive
slurry
Transducer
~
power
supply
Nozzle Abrasive
slurry
Transducer
Up-down vibration of tool
hammers the abrasive particles
against workpiece, causing cutting
Main uses of USM:
- Welding plastics (package sealing)
- Wire-bonding (IC chips)
- Machining brittle materials
8. Water-Jet, Abrasive Water-Jet Machining
- Workpiece is fractured by impact from
high pressure (~400 MPa) water-jet
- No heat no thermal stress, damage
Common applications:
- Fast and precise cutting of fabrics
- Vinyl, foam coverings of car dashboard panels
- Plastic and composite body panels used in the interior of cars
- Cutting glass and ceramic tiles
