This presentation gives an information about Introduction to Non-Traditional Machining covering the syllabus of Non Traditional Machining.

1. 6/3/2014 1Hareesha N G, Dept of Aero Engg, DSCE

2. Review of Machining
• Machining is a generic term, applied to material removal
processes.
• Traditional machining: turning, milling, drilling, grinding, etc.
• Metal cutting refers to processes in which excess metal is
removed by a harder tool, through a process of extensive plastic
deformation or controlled fracture.
• Non-traditional machining: chemical machining, ECM, EDM,
EBM, LBM, machining of non-metallic materials.
6/3/2014 Hareesha N G, Dept of Aero Engg, DSCE 2

3. Nontraditional Machining
• Chemilling
• Electrochemical machining
• Electrical discharge machining
• High energy beam machining
• Water jet/Abrasive water jet machining
• Ultrasonic machining
• Machining of non-metallic materials
6/3/2014 Hareesha N G, Dept of Aero Engg, DSCE 3

4. Chemical Machining (Chemilling)
• Used to produce shallow
cavities (<12mm) on large
areas.
• A maskant is applied over
areas you don’t want to
machine.
• Place the part in a chemical
bath (acid or alkali
depending upon the metal)
• Control temperature and
time of exposure to control
material removal
• Material removal rate is
slow, 0.025-0.1 mm/min
6/3/2014 Hareesha N G, Dept of Aero Engg, DSCE 4

5. Electro-Chemical Machining (ECM)
• Works on the principle of
electrolysis
• 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).
• Material removal rate is
2.5-12 mm/min
depending on current
density.6/3/2014 Hareesha N G, Dept of Aero Engg, DSCE 5

6. Electrical Discharge Machining
(EDM)
• The tool (electrode) usually acts as a
cathode and is immersed in a
dielectric fluid.
• DC voltage (~300V) is applied in
modulated pulses (200-500K Hz).
• The dielectric breaks down (sparking
at around 12,000 deg F) when gap is
small.
• The sparks erodes the workpiece in
the shape of the tool.
• The tool is progressively lowered as
the workpiece erodes.
• Material removal rate is typically 300
mm3/min
• Tool wear ratio 3:1 with metallic
electrodes, 3:1-100:1 with graphite
electrodes6/3/2014 Hareesha N G, Dept of Aero Engg, DSCE 6

7. Die Sinker and Wire EDM
• Die sinker EDM
– The die (copper or graphite)
sinks into the part as it sparks
away the workpiece.
– Most common injection
molding die process.
• Wire EDM
– The electrode (brass, copper, W,
Mo, 0.08-3 mm) is a wire that
traverses through the part.
– Common for extrusion dies.
• Electrical discharge drilling
• Electrical discharge grinding
6/3/2014 Hareesha N G, Dept of Aero Engg, DSCE 7

8. Examples of Die Sinker and Wire EDM
6/3/2014 Hareesha N G, Dept of Aero Engg, DSCE 8

9. Water Jet and Abrasive Water Jet
Cutting
• High pressure
water (20,000-
60,000 psi).
• Can cut
extremely thick
parts (5-10
inches possible).
• Thickness
achievable is a
function of
speed.
6/3/2014 Hareesha N G, Dept of Aero Engg, DSCE 9

10. Abrasive Waterjet and Waterjet
Part Examples
6/3/2014 Hareesha N G, Dept of Aero Engg, DSCE 10

11. High Energy Beam Machining
(a) Electron beam machining
Cutting and hole making on thin
materials; very small holes and
slots (0.1-0.3mm depending on
thickness); heat affected zone;
require vacuum, expensive
equipment; 1-2 mm3/min.
(b) Laser beam machining
Cutting and hole making on thin
materials; heat-affected zone; does
not require a vacuum; but
expensive equipment; consume
much energy; 0.5-7.5 mm/min
depending on thickness.6/3/2014 Hareesha N G, Dept of Aero Engg, DSCE 11

12. Machining of Nonmetallic Materials
• Machining of ceramics:
– Abrasive machining, including abrasive water
jet machining
– Laser beam machining
– Laser assisted machining
Laser assisted machining6/3/2014 Hareesha N G, Dept of Aero Engg, DSCE 12

13. Ultrasonic Machining of Ceramics
6/3/2014 Hareesha N G, Dept of Aero Engg, DSCE 13

14. Machining of Plastics and Composites
• Plastics need to be carefully supported.
• Requires large rake and relief angles, high cutting speed, and
low feed.
• Trimming of plastic parts using water jet cutting or abrasive
water jet cutting.
• Common problems in cutting composites
– Delamination, poor edge finish, and fiber pull out.
• Use abrasive water jet cutting.
• Metal matrix composites such as carbide tool bits can be
machined using diamond tools, EDM, and ECM.
6/3/2014 Hareesha N G, Dept of Aero Engg, DSCE 14

15. Characteristics of Machining
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