a ppt on abrasive jet machining

1. Abrasive Jet Machining
(AJM)
BY
SHIVAM PANDEY
GME122705

2. INTRODUCTION
Abrasive jet machining is the material removal process where the material is removed by
high velocity stream of air/gas or water and abrasive mixture .
An abrasive is small, hard particle having sharp edges and an irregular shape .
High velocity jet is aimed at a surface under controller condition .

3. 3
Machining System

4.  A gas (Nitrogen, CO2 or air) is supplied at 2 – 8 kg/cm2
 Oxygen should never be used. (because, it causes violent chemical
action with the workpiece chips or abrasive particles).
 Gas passes through a mixing chamber after filtration and regulation.
 In the mixing chamber, abrasive particles (10 – 40 m) are present
and vibrated at 50 Hz.
 Amplitude of vibration – to control the feed rate of abrasives.
 (Gas + abrasives) - passed through a 0.45 mm diameter tungsten
carbide nozzle at a speed of 150 – 300 m/s.
 The nozzle is directed over the area to be machined.
Machining System – Contd.

5. Components of Abrasive Jet
Machining
o Abrasive delivery system
o Control system
o Gas delivery system
o Nozzle
o Mixing chamber
o Motion system

6. Fig . Schematic diagram of AJM

7. Abrasive Jet Machining

8. Process Parameters and
Machining Characteristics
Abrasive : Material – Al2O3 / SiC / glass beads
Shape – irregular / spherical
Size – 10 ~ 50 μm
Mass flow rate – 2 ~ 20 gm/min
Carrier gas : Composition – Air, CO2, N2
Density – Air ~ 1.3 kg/m3
Velocity – 500 ~ 700 m/s
Pressure – 2 ~ 10 bar
Flow rate – 5 ~ 30 lpm
Abrasive Jet : Velocity – 100 ~ 300 m/s
Mixing ratio – mass flow ratio of abrasive to gas
Stand-off distance – 0.5 ~ 5 mm
Impingement Angle – 600 ~ 900
Nozzle : Material – WC
Diameter – (Internal) 0.2 ~ 0.8 mm
Life – 10 ~ 300 hours

9. Abrasive Jet Machining
effect of process parameters on MRR

10. Abrasive Jet Machining
In Abrasive Jet Machining (AJM), abrasive particles are made to impinge
on the work material at a high velocity. The high velocity abrasive particles
remove the material by micro-cutting action as well as brittle fracture of the
work material.

11. Advantages
o Extr emely fas t s etup & pr ogr amming
o N o s tar t hole r equir ed
o There is only one tool
o Low c apital c os t
o Les s vibr ation
o N o heat gener ated in w or k piec e
o Envir onmentally fr iendly

12. Disadvantages
o Low metal removal rate
o Due to stay cutting accuracy is affected
o Abrasive powder cannot be reused
o Tapper is also a problem

13. 13
o The removal rate is slow.
o Stray cutting can’t be avoided (low accuracy of  0.1 mm).
o The tapering effect may occur especially when drilling in metals.
o The abrasive may get impeded in the work surface.
o Suitable dust-collecting systems should be provided.
o Soft materials can’t be machined by the process.
o Silica dust may be a health hazard.
o Ordinary shop air should be filtered to remove moisture and oil.
Limitations

14. Conclusion
o The better performance , and the applications
represented above statements confirm that
ABRASIVE JET MACHINING is continue to
expand .
o The new software’s used to minimize time and
investments , there by making it possible for
more manufacturers of precision parts to install
AJM centers .