Abrasive Jet Machining

Abrasive Jet Machining

Introduction

         Abrasive jet machining (AJM) is an abrasive  blasting machining process that uses abrasives propelled by a high velocity gas to erode material from the workpiece. Common uses include cutting heat-sensitive, brittle, thin, or hard materials. Specifically it is used to cut intricate shapes or form specific edge shapes.

Important parameters

•Abrasive particle size : 0.025mm

•Pressure of gas : 4 bar

•Speed : 1000 Km/h

•Grit material : Aluminum oxide, silicon carbide, glass beads

Block Diagram

Part Introduction

Mixing chamber: 

It is used to mix the gas and abrasive particles

.

Filter: 

It filters the gas before entering the compressor and mixing chamber.

Hopper: 

Hopper is used for feeding the abrasive powder.

Pressure gauges and flow regulators: 

They are used to control the pressure and regulate the flow rate of abrasive jet.

Vibrator: 

It is provided below the mixing chamber. It controls the abrasive powder feed

rate in the mixing chamber.

Nozzle:

It forces the abrasive jet over the work piece. Nozzle is made of hard and

resistant material like tungsten carbide

Working Principle

• Dry air or gas is filtered and compressed by passing it through the filter and

compressor.

• A pressure gauge and a flow regulator are used to control the pressure and

regulate the flow rate of the compressed air.

• Compressed air is then passed into the mixing chamber. In the mixing

chamber, abrasive powder is fed.

• A vibrator is used to control the feed of the abrasive powder. The abrasive

powder and the compressed air are thoroughly mixed in the chamber. The

pressure of this mixture is regulated and sent to nozzle.

The nozzle increases the velocity of the mixture at the expense of its pressure.

A fine abrasive jet is rendered by the nozzle. This jet is used to remove

unwanted material from the workpiece.

Advantages of AJM

1) Surface of the work piece is cleaned automatically.

2) Smooth surface finish can be obtained.

3) Equipment cost is low.

4) Hard, brittle and materials high strength can be easily machined.

Disadvantages of AJM

1) Metal removal rate is low.

2) Nozzle life is less. Nozzle should be maintained periodically.

•tungsten carbide nozzles : About 12 to 30 hours,

•sapphire nozzles : About 400 hours

3) Abrasive Jet Machining cannot be used to machine soft materials.