SURESH BEERA

M.Tech Ist year

12ETMM11

Materials Engineering

SEST,UOH.

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Introduction

Machining

Conventional machining

Unconventional maching

Based on Mechanical energy (WJM,AJM,AWJM)

JET : A rapid stream of liquid or gas forced out of a small opening.

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Working principle AWJM The cutter is commonly

connected to a high pressure water pump where the water is then ejected from the nozzle, cutting through the material by spraying it with the jet of high speed water.

Additives in the form of suspended grit or other abrasives, such as garnet and aluminum oxide can assist in this process.

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AWJM - Elements

AWJM Setup

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Schematic Setup of AWJM

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Water is pumped at a sufficiently high pressure, 200-400 MPa

“Intensifier” works on the principle of pressure amplification using hydraulic

cylinders of two different cross-sections.

When water at such a pressure is passed through a suitable orifice (nozzle

having = 0.2 – 0.4 mm), the potential energy of water is converted into

kinetic energy.

This yields high velocity (~ 1000 m/s) jet of water.

Such a high velocity water jet can machine thin sheets/foils of aluminium,

leather, textile, frozen foods, etc.

commercially pure water (tap water) is used for machining.

Basic Methodology

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Injection & SuspensionHeads

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Cutting Heads

Schematic View Photographic View

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Catcher

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Typical Parameters in Entrained AWJM

Orifice – Sapphires – 0.1 to 0.3 mm

Focussing Tube – WC – 0.8 to 2.4 mm

Pressure – 2500 to 4000 bar

Abrasive – garnet and olivine - 125 to 60 micron

Abrasive flow rate - 0.1 to 1.0 kg/min

Stand off distance – 1 to 2 mm

Machine Impact Angle – 60o to 900

Traverse Speed – 100 mm/min to 5 m/min

Depth of Cut – 1 mm to 250 mm

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Material Removal in AWJM Mechanism of material removal in WJM or AWJM is rather complex.

In AWJ machining of ductile materials, material is mainly removed by low

angle impact of abrasive particles.

Further at higher angle of impact, the material removal involves plastic

failure of the material at the sight of impact.

In AWJ machining of brittle materials, material would be removed due to

crack initiation and propagation because of brittle failure of the material.

In water jet machining, the material removal rate may be assumed to be

proportional to the power of the water jet.

Advantages

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• Cut virtually any material. (pre hardened steel, mild steel, copper, brass, aluminum; brittle materials like glass, ceramic, quartz, stone)• Cut thin stuff, or thick stuff.• Make all sorts of shapes with only one tool.• No heat generated.• Leaves a smooth finish, thus reducing secondary operations.• Modern systems are now very easy to learn and safe.•Unlike machining or grinding, waterjet cutting does not produce any dust or particles that are harmful if inhaled.• Waterjet cutting can be easily used to produce prototype parts very efficiently

This part is shaped with waterjet using one tool. Slots, radii, holes, and profile in one 2 minute setup.

Disadvantages

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• One of the main disadvantages of abrasive waterjet cutting is that a limited number of materials can be cut economically. While it is possible to cut tool steels, and other hard materials, the cutting rate has to be greatly reduced, and the time to cut a part can be very long. Because of this, waterjet cutting can be very costly.• Another disadvantage is that very thick parts can not be cut with waterjet cutting and still hold dimensional accuracy. If the part is too thick, the jet may dissipate.

Waterjet lag

AWJM vs. other Modern process

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After laser cutting After waterjet cutting Abrasive Water jets are much faster than EDM.

After plasma cutting After waterjet cutting

Practical Applications Edge finishing

Radiusing

De-burring

Polishing

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Paint removal

Cleaning

Cutting soft materials

Cutting frozen meat

Textile, Leather industry

Peening

Pocket Milling

Drilling & Turning

Nuclear Plant Dismantling

AWJM - Applications

SUMMARY

Only abrasives and water is used in AWJM

In AWJM no heat generate during machining

It has faster cutting rates, longer component life and tighter tolerances will be achievable

AWJM that embrace simplicity and have a small environmental impact

AWJM is have more advantage than other modern machining process

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References Modern Machining process P.C.Pandey ,H.S. Shan,tata

mcgraw hill publication.

Principles of AWJM Andreas W.Momber,Radovan Kavacevic

www.flowcorp.com

www.flowwaterjet.com/Abrasive-Waterjet

www.waterjets.org

www.aqua-dynamics.co.uk

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THANK YOU24-10-2014 20