Abrasive jet machining is a machining process that uses a high-pressure stream of abrasive particles to erode material from a workpiece. It allows for precision machining of brittle materials with no heat affected zone and surface finishes as fine as 0.4-1.2 micrometers. The process involves mixing abrasive particles with a pressurized gas before passing them through a nozzle to eject them at speeds up to 300 m/s onto the workpiece. Factors like abrasive type, nozzle characteristics, gas pressure and flow rates influence the machining rate, accuracy and surface quality achievable.

1. Pallavi Priyambada Badajena Guided By
Debashish Bose Rajendra Kumar Mohanty
Deepak Kumar Mohanty Lecturer
Dillip Kumar Sahoo Dept.Of Mechanical Engg.
Debesh Jena

2.  Introduction
 History
 Working Principle
 Diagram
 Equipments
 Process Parameters
 Process Characteristics
 Schematic Diagram
 Types of Abrasive
 Market Price Of Compressor
 Abrasive Particle
 Carrier Gas
 Nozzle And Jet Velocity
 Stand-off Distance
 Design Of AJM In Autocad
 Material Removal Rate
 Accuracy
 Surface Finish
 Application
 Advantages
 Disadvantages
 References

3.  There are many situations where the processes of
manufacturing we’ve learned cannot produce the
required dimensional accuracy and or surface finish.
 Fine finishes on ball/roller bearings, pistons, valves, gears,
cams, etc.
 The best methods for producing such accuracy and finishes
involve Abrasive Jet Machining
 Abrasive Jet Machining, It is an unconventional
machining process based on mechanical energy for
cutting, deburring and cleaning hard and brittle
materials.

4.  In 1979, Dr. Mohamed Hashish working at Flow
Research, began researching methods to increase the
cutting power of the abrasive jet so it could cut metals,
and other hard materials.
 Dr. Hashish, regarded as the father of the abrasive jet,
invented the process of adding abrasives to the plain
abrasive jet. He used garnet abrasives, a material
commonly used on sandpaper. With this method, the
jet (containing abrasives) could cut virtually any
material.

5.  Abrasive Jet Machining helps in removing materials
from the brittle and heat sensitive materials by the
application of high speed stream of abrasive particles.
 Micro-abrasive particles are propelled by inert gas at
velocities of upto 300 m/sec, which result in erosion
 The material removal is due to erosive action of a high
pressure jet.

6.  In particular drilling of holes of minimum diameter
and maximum depth with greater accuracy and surface
finish.
 Material is removed by fine abrasive particles, usually
about 0.001 in (0.025 mm) in diameter.
 Pressures for the gas range from 25 to 130 psig (170–
900 kPag) and speeds can be as high as 300 m/s.

8.  High pressure gas supply source
 Powder mixing chamber
 Control valve
 Nozzle
 Hood
 Exhaust systems
 A filter and water separator unit

9.  The abrasive powder is held in a hopper, which is fed
to the mixing chamber to mix with carrier gases.
 A jet stream of abrasive forms as the mixture comes
out of the nozzle.
 At the working table a dust collection hood is
provided, with a vacuum dust collector.

10. Nozzle
 Nozzle tips are made of hard materials like tungsten
carbide or sapphire.
 Tungsten carbide nozzles give a life of about 15 hours
with silicon carbide abrasive.
 The nozzle diameter is in the range of 0.13 to 1.25 mm

11.  MRR, machining accuracy, surface roughness and
nozzle wear are influenced by
 Size and distance of the nozzle.
 Composition, strength, size, and shape of abrasives
 Flow rate
 Composition, pressure, and velocity of the carrier gas.
 The mass flow rate of the gas decreases with an
increase in the abrasive flow rate

12.  Hence the mixing ratio increases and causes a
decrease in the removal rate because of the decreasing
energy available for material removal
 High nozzle pressures result in a greater removal rate,
but the nozzle life is decreased

15.  Refractory-Powder
 Refractory-Loose Grit Sand
 Bonded Abrasives
 Coated Abrasives
 Blasting/Lapping/Polishing Abrasives

16.  The market price of air compressor vary over a wide
range.
 Its value depends on the pressure with which the
abrasive particle is to be bombarded on the
workpiece(Glass).
 20-25cfm – Rs70,000
 10-12cfm – 35,000

17.  Material – Al2O3 / SiC / glass beads
 Shape – irregular / spherical
 Size – 10 ~ 50 μm
 Mass flow rate – 2 ~ 20 gm/min

18.  Composition – Air, CO2, N2
 Density – Air ~ 1.3 kg/m3
 Velocity – 500 ~ 700 m/s
 Pressure – 2 ~ 10 bar
 Flow rate – 5 ~ 30 lpm

19.  Material – WC / sapphire
 Diameter – (Internal) 0.2 ~ 0.8 mm
 Life – 10 ~ 300 hours
 Velocity – 100 ~ 300 m/s

20.  Stand-off distance – 0.5 ~ 5 mm
 Impingement Angle – 600 ~ 900

22. • The metal removal rate depends upon
 The diameter of nozzle
 Composition of abrasive-gas mixture
 Jet pressure
 Hardness of abrasive particles and that of work material
 Particle size
 Velocity of jet
 Distance of work piece from the jet

24. • In AJM, tolerances in the region of ±0.05 mm can be
achieved for precision works.
• In normal production jobs tolerance up to 0.1mm are
possible.
• The corner radius can be up to 0.1 mm, while taper is
about 0.05 mm per 10 mm of depth.

25.  Surface finish in AJM is in the range of 0.4 to 1.2 mm
depending upon the abrasive particle size.
 There is no heat affected zone, since the surface while
machining remains at room temperature, as the carrier
gas acts as the coolant.
 The effect of impact on the surface is less than 2 μm

26.  AJM can be used conveniently for fragile materials like
glass.
 Its applications include removing oxides from metal
surfaces, deburring, etching patterns, drilling and
cutting of thin sections.
 The process is not suitable for cutting soft materials
since the abrasive particles may get embedded into the
soft material.

27.  Cutting action is shock less.
 Ability to cut fragile and heat sensitive materials
without damage.
 Ability to cut intricate hole shapes in materials of any
hardness and brittleness.
 No variation due to surface irregularities and tool wear
as in conventional machining.
 Low capital cost.
 AJM units are easy to operate and maintain

28.  It is not suitable for mass material removal.
 It needs a dust control system.
 The abrasives may get embedded in softer material.
 The nozzle life is limited.
 The cutting motion is to be properly controlled.

29.  Boothroyd, Geoffrey; Knight, Winston A.
(1989),Fundamentals of machining and machine
tools(2nd ed.), Marcel Dekker, pp. 478–479,
 Todd, Robert H.; Allen, Dell K.; Alting, Leo
(1994), Manufacturing Processes Reference Guide,
Industrial Press Inc., pp. 2–5, .
 Chastagner, Matthew W.; Shih, Albert J.
(2007), "ABRASIVE JET MACHINING FOR EDGE
GENERATION", Transactions of NAMRI/SME35: 359–
366