Conducted a Presentation on Abrasive Waterjet Machining on Expro 2018 at Madras Institute of technology, Chennai.

1. ABRASIVE WATERJET
MACHINING

3. CONTENT
• Introduction
• Process
• Mechanism
• Process Parameters
• Applications
• Advantages
• Disadvantages

4. Introduction
• Developed in 1974 to clean metal prior to surface treatment of the metal.
• AWJM is non-traditional or non-conventional machining process.
• This belongs to mechanical group of non-conventional processes.
• Harder materials such as glass, ceramics, concrete, and tough
composites can be cut.
• In these processes, the mechanical energy of water and abrasive phases
are used to achieve material removal or machining. The addition of
abrasives to the water jet enhanced MRR and produced cutting speeds
between 51 and 460 mm/min.
• Generally, AWJM cuts 10 times faster than the conventional machining
methods of composite materials.

5. Process
• Fine, high pressure(1500-4000bar), high velocity of
water jet is bombarded onto the work surface.
• High velocity water jet is directed at a target in such a
way that the velocity is reduced to zero on striking the
workpiece.
• High pressure and potential energy is converted to
kinetic energy.
• If Pressure> Strength of material, Erosion happens

6. Mechanism
• Given amount of energy is concentrated onto a very small
point to cause the material removal.
• Energy is of order 10^10 watt/mm^2.
• On striking the K.E is converted into the pressure
energy(stagnation pressure).
• Erosion- Localised compressive failure which occurs
when the local fluid pressure exceeds the strength of the
target material.
• For ductile material- erosion due to shearing action.

7. Micro-mechanism of material
removal
Plastic deformation
The process of separating ductile material.

8. Impact of abrasive material on surface of brittle material

9. Macro-mechanism of material
removal
• Formation of different regions in water jet.

10. Machine Setup

11. Schematic View

12. Intensifier Pump

13. • Water is pumped at sufficiently high pressure, 2000 -
4000bar using intensifier technology.
• Water is passed through a suitable orifice (0.2 to 0.4
mm dia) where the P.E energy is converted to K.E
resulting in high velocity jet (1000m/s).

15. Nozzle

16. Nozzle
• In Entrained AWJM, the abrasive jet, which finally comes
from the focusing tube or nozzle, can be used to machine
different materials.
• Jewel tip.

17. Catcher

18. Process parameters
• Mechanism of metal removal —Brittle materials – crack initiation and
propagation- brittle failure.
• Process parameters:
Orifice – Sapphires – 0.1 to 0.3 mm
Focusing Tube – WC – 0.8 to 2.4 mm
Pressure – 2500 to 4000 bar
Abrasive – garnet and olivine - #125 to #60
Abrasive flow - 0.1 to 1.0 Kg/min
Stand off distance – 1 to 2 mm
Machine Impact Angle – 60o to 900
Traverse Speed – 100 mm/min to 5 m/min
Depth of Cut – 1 mm to 250 mm

19. Benefits
• Cheaper than other processes.
• Cut virtually any material. (pre hardened steel, mild steel, copper, brass,
aluminum; brittle materials like glass, ceramic, quartz, stone) • Cut thin stuff,
or thick stuff. • Make all sorts of shapes with only one tool.
• No heat generated.
• Leaves a satin smooth finish, thus reducing secondary operations.
• Clean cutting process without gasses or oils.
• Modern systems are now very easy to learn.
• Are very safe.
• Machine stacks of thin parts all at once.

20. Disadvantages
• Clamping
• Number of materials can be cut economically is low.
• While it is possible to cut tool steels, and other hard materials, the
cutting rate has to be greatly reduced, and the time to cut a part
can be very long.
• If the part is too thick, the jet may dissipate some, and cause it to
cut on a diagonal, or to have a wider cut at the bottom of the part
than the top. It can also cause a rough wave pattern on the cut
surface.
• Long run may cause jewel wear.

23. Applications
• Paint removal
• Cutting soft materials
• Cutting frozen meat
• Textile, Leather industry
• Surgery
• Peening
• Cutting
• Pocket Milling
• Drilling
• Composite fibres can be cut.

24. Thank you…
Presented by:
KEERTHIVASAN R