The document describes abrasive jet machining. It involves removing material from a workpiece using a high-velocity stream of air or gas mixed with abrasive particles. Key components include an air compressor, abrasive delivery system, nozzle, and motion system to direct the abrasive stream. The mixing tube is where abrasive mixes with pressurized air before exiting the nozzle to erode material. A CNC motion system provides automated precision control over the machining process.

2.  Material removal process where the material is removed by
high velocity stream of air/gas or water and abrasive
mixture directed on the work piece surface.
 The material removal process is mainly caused by brittle
fracture by impingement and then by erosion.
 An abrasive is small, hard particle having sharp edges and an
irregular shape.

3.  Air Compressor
 Abrasive delivery system
 Nozzle
 Mixing tube
 Motion system

4.  Air compressors compress the
air to high pressure taking input
energy from electric motor or
internal combustion engine.
 In abrasive jet machining high
pressure air jet is required so
that the suspended particles in
it can strike the work piece at
high velocity.
 Positive-displacement air compressors work by forcing air
into a chamber whose volume is reduced to compress the air.

5.  Auto abrasive delivery system has the capability of
storing abrasive & delivery the abrasive to the bucket.
 It works auto programming system by help of once
measuring record & no adjustment or fine tuning system.
High sensitive sensor gives extremely reliable & repeatable.

6.  All abrasive jet systems use the same basic
two stage nozzle . First , water passes through
a small diameter jewel orifice to form a
narrow jet.
 The abrasive particles are accelerated by the
moving stream of water & they pass into a
long hollow cylindrical ceramic mixing tube.
 Generally two type of nozzle use , right angle
head & straight head.

7.  The mixing tube is where the
abrasive mixes with the high
pressure water.
 The mixing tube should be replaced
when tolerances drop below
acceptable levels.
 For maximum accuracy , replace the
mixing tube more frequently.

8.  In order to make precision parts , an abrasive jet system
must have a precision x-y table and motion control
system.
 Tables fall into three general categories.
 Floor-mounted gantry systems
 Integrated table/gantry systems
 Floor-mounted cantilever systems
 Automation of AJM is done by implementing Computer
Numerical Control (CNC) into the motion system.

9.  A numerical control system in which the data handling, control
sequences, and response to input is determined by an on-board
computer system at the machine tool.
 A CNC machine consists of the following 6 major elements:
 Input Device
 Machine Control Unit
 Machine Tool
 Driving system
 Feedback Devices
 Display Units

11.  Easier to program.
 Easy storage of existing programs.
 Easy to change programs.
 Avoids human errors.
 CNC machines are safe to operate.
 Complex geometry is produced as cheaply as simpler ones.
 Usually generates closer tolerances than manual machines.

12.  Costly Setup.
 Skilled operators.
 Computers and programming knowledge required.
 Maintenance is difficult.

14.  Air from the atmosphere is compressed by the compressor
and is delivered to the mixing chamber vie the filter and
regulator.
 The mixing chamber contains the abrasive powders and is
made to vibrate by an electric motor and cam arrangement.
 Then the abrasive particles are passed into a connecting
hose leading to the nozzle.
 This abrasive and gas mixture emerges from the orifice of
nozzle at high velocity.
 The feed rate of abrasive air is controlled by the amplitude
of vibration of the mixing chamber.

15.  A pressure regulator installed in the system controls the gas
flow and pressure.
 The nozzle is mounted on a plate which is screwed to the
frame.
 The work piece is moved by moving the x-y table to control
the size and shape of the cut.
 Dust removal equipment is necessary to protect the
environment.

16.  It has the ability to cut intricate holes shape in materials of
having any hardness and brittleness.
 It can cut fragile and heat sensitive material without
damage as physical tool is absent.
 No alteration in microstructure of materials as no heat is
generated.
 Smooth finish can be obtained.
 Capital cost is low.

17.  Material removal rate is low and hence its application is
limited to small scale machining.
 Stray strings can occur and so its application is limited.
 Embedding of the abrasive particles in the work piece
surface may occur while machining softer material.
 The abrasive material may accumulate at nozzle and fail the
process if moisture is contained in the air.
 It cannot be used to drill blind holes.

18.  Machining of brittle materials and heat sensitive materials
like quartz glass, sapphire, mica and ceramics.
 Countering, drilling, cutting slot, thin sections, de-burring
for producing integrate shapes in hard and brittle materials.
 Cleaning and polishing of plastics like nylon.
 Micro machining is possible in brittle materials.