ABRASIVE JET MACHINING

What is abrasive jet machining ?

It 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 .

components of abrasive jet

machining

Abrasive delivery system Control system Pump Nozzle Mixing tube Motion system

1. abrasive delivery system

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

2.Control system

The control algorithm that computes exactly how the feed rate should vary for a given geometry in a given material to make a precise part .

The algorithm actually determines desired variation in the feed rate & the tool path to provide an extremely smooth feed rate .

3.pump

Crankshaft & intensifier pump are mainly use in the abrasive jet machine .

The intensifier pump was the only pump capable of reliably creating pressures high .Crankshaft pumps are more efficient than intensifier pumps because they do not require a power

robbing hydraulic system ultra high pressure

& more stroke per minute .

4.nozzle

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 .

Fig. Of nozzle

5. Mixing tube

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 .

6.Motion system

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 systemsFloor-mounted cantilever

systems

working process

High pressure water starts at the pump , and is delivered through special high pressure plumbing to the nozzle .

At the nozzle , abrasive is introduced & as the abrasive/water mixture exits , cutting is performed .

Once the jet has exited the nozzle , the energy is dissipated into the catch tank , which is usually full of water & debris from previous cut .

fig . schematic diagram of ajm

ajm features

There are main features of AJM

Obtainable tolerancesMaterial to machineMaterial thicknessAccuracy of tableStability of tableControl abrasive jet

Machine aspects

Around curves Inside cornerFeed rateAcceleration Nozzle focus Speed cuttingPump pressureHardness & thicknessSoftware controlling the motionPower at the nozzle

Types of abrasive materials

Different types of abrasive are used in abrasive jet machining like garnet , aluminum oxide , olivine , silica sand , silicon carbide ,etc .

Virtually any material can be cut by using abrasive jet machining method , i.e harder

materials like titanium to steel.

Abrasive particles must be hard ,high toughness,

irregular in shape & edges should be sharp .

Advantages Extremely fast setup &

programming No start hole requiredThere is only one toolLow capital costLess vibrationNo heat generated in work

pieceEnvironmentally friendly

Disadvantages Low metal removal rateDue to stay cutting accuracy is

affectedAbrasive powder cannot be

reusedTapper is also a problem

conclusion

The better performance , and the applications represented above statements confirm that

ABRASIVE JET MACHINING is continue to expand .

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 .