Mechanical Engineering

1. PRESENTED BY
Soumyabrata Basak

2. INTRODUCTION
AJM is a metal removing process and it is invented in
1967. A jet of inert gas consisting of very fine abrasive
particles strikes the work piece at high velocity
resulting in material removal through erosive action.
This erosive action has been employed for cutting,
cleaning, etching, polishing and debarring. This
method of metal removal is quite effective on hard and
brittle materials (viz glass, silicon, tungsten, ceramics,
etc). But not so effective on soft materials like
aluminum, rubber, etc. It can produce fine and
complicated details on the parts made of very brittle
materials.

3. PRINCIPLE OF OPERATION
In abrasive jet machining material
is removed by the erosive action of
high velocity stream of fine abrasive
particles imparting on the work
surface. High pressure air or gas is
supplied to the mixing chamber
containing the fine abrasive
particles. These high pressure
abrasive particle and gas mixture
are passed through the small nozzle
and the erosion caused by their
impact at high speed removes the
metal of the work piece

4. PROCESS DESCRIPTION

5. PROCESS PARAMETERS
The parameters that influence the rate of metal removal
and accuracy of machining in this process are:
Abrasive
Carrier gas
Abrasive jet
Nozzle
Work material
Stand of distance
Shape of cut

6. ABRASIVE
Generally aluminum oxides powder or silicon carbide is
used as the abrasive. Dolomite is used for light
cleaning and etching. The abrasive particle size is a
dominant factor in AJM and best result obtained with
particle size in the range of 15 to 50 micron.

7. ABRASIVE JET
The outgoing stream of abrasive particles and gas from
nozzle is known as abrasive jet. Velocity of abrasive jet
is around 100-300 m/s.

8. WORK MATERIAL
AJM is recommended for the processing of brittle
materials such as glass, ceramics, refractories, etc.
Most of the ductile materials are practically
unmachinable by AJM.

9. ADVANTAGES
Ability to cut intricate cavity and holes of any shape of
harder materials.
Brittle material of thin sections can be easily machined
without risk of breaking.
Low capital cost.
Ability to cut fragile and heat sensitive material
without any damage.
No heat is generated during this process.
There is no part chatter or vibration.
Good for difficult to reach areas.

10. DISADVANTAGES
Metal removal rate is very low.
It requires some kind of dust collection system.
The machining accuracy is poor.
Nozzle wear rate is high.
Abrasive powder can not be reused.

11. APPLICATION
Fine drilling and cutting thin sections of metal.
The process is mainly used for surface etching.
Frosting and abrading of glass articles.
It is often used for cleaning and polishing of plastics.
Used for trimming resistors of hybrid power amplifier circuit.
Used for micro machining of brittle materials.
Used for removing glue and paint from paintings and surface.
It is used for cutting Titanium coil.
Used for cutting and machining of fragile material like
germanium, silicon, etc.
It is used for manufacturing electronics devices and marking on
them.

12. REFERENCES
MANUFACTURING SCIENCE BY AMITABHA
GHOSH & AHSOK KUMAR MALLIK
MANUFACTURING ENGINEERING & TECHNOLOGY
BY KALPAK JIAN