Water Jet Machining: Recent development

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Recent Recent development of development of

Water Jet Water Jet MachiningMachining

Reyad Mehfuz

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Water Jet Machining- Water Jet Machining- recent developmentrecent development

OverviewOverview

1. Introduction

2. General overviews

3. Recent developments

4. Conclusion

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IntroductionIntroduction

First water jet machining patented in 1960 by Norman Franz

First industrial application as a new cutting tool in the early 1970

Usually used to cut soft materials like paper, food, plastics, cardboard, wood, leather

Only very thin sheets of metals can be cut with pure water jet.

It is also not suitable for cutting glass or high strength composites.

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Introduction (Contd.)Introduction (Contd.)

Removes material through the erosion effects of a high velocity, small diameter jet of water

Same principle of ‘rain-erosion phenomenon’ occurring on high speed aircrafts.

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Introduction (Contd.)Introduction (Contd.)

Two steps of cutting:

1. High pressure pump or intensifier pressurizes water to produce the energy required for cutting.

2. Water is then focused through a small precious stone orifice to form an intense cutting stream.

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AdvantagesAdvantages

Water is cheap, non-toxic, readily available, and can be disposed easily.

Any contour and sharp corners can be cut cleanly. The operation is possible in both horizontal and vertical positions.

Absence of heat-affected zone.

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Advantages (Contd.)Advantages (Contd.)

Sticky materials can be smoothly cut without causing any clogging.

Dust- free process. Minimum kerf-width No contamination problem. Easy automation.

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MechanismMechanism

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Process ParametersProcess Parameters

velocity of the jet or jet pressure stand-off-distance, nozzle diameter, traverse rate, feed rate and depth of cut, and the properties of the material being cut.

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Effect of jet pressureEffect of jet pressure

If

Jet Pressure

then

Depth of cut

MRR

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Effect of stand-off Effect of stand-off distancedistance

reduction in nozzle pressure with decreasing distance

a reduction in

the jet velocity with increasing distance

1

2

12

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Effect of traverse rateEffect of traverse rate

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Effect of nozzle Effect of nozzle diameter diameter

Nozzle dia

Depth of cut

Nozzle diameter

0123456789

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0 200 400 600 800 1000

Pressure (MPa)

Dep

th o

f cut

(mm

)

0.08 mm

0.1 mm

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Recent Recent DevelopmentDevelopment

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High pressure water jetHigh pressure water jet

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High pressure water jet: High pressure water jet:

Use of high pressure water jet (900MPa) for machining sheet metal of different materials, Al and Zn

Fracture mechanism varies with the material properties.

Aluminium shows ductile fracture while zinc shows brittle fracture.

Louis et al. (2003-04)Louis et al. (2003-04)

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High pressure water jet High pressure water jet (contd.)(contd.) high pressure water jet application using

smaller orifice have better power efficiencies

increases both maximum cutting speed and depth of cut with the increase of pressure.

Suzulu et al. (2004-05)Suzulu et al. (2004-05)

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Nozzle shapeNozzle shape

Rectangular jets are found more efficient for improving surface processing techniques.

Specific water consumption by the rectangular nozzle was found significantly reduced and the productivity greater than that of the commercial round nozzles.

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Nozzle materialsNozzle materials

water quality and chemistry, the operating pressure, and the nozzle design.

Parameters for nozzle materials wear

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Nozzle materials (contd.)Nozzle materials (contd.)Recommended Nozzle Material

Operating Conditions

Carbide • Dirty, unfiltered water; pressures below 140 MPa (20,000 psi)

Steel • Water filtered to 25 micron or better, pressures below 140 MPa

Sapphire • Water filtered to 10 micron or better, pressures above 140 MPa

Diamond nozzle shows better performance over sapphire nozzle at high pressure in terms of jet stability. (Louis et al.)

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Water jet-cleaning Water jet-cleaning nozzlesnozzles

Cone Jet Poor

Fan Jet Good

Resonating jet Poor

Cavitating jet Better

Nozzle types Performance

•Erosion rate•Erosion depth

Basis

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Water jet formingWater jet forming

Promising in the field of the rapid prototyping and could be used to form thin metal sheet without using dies in the future.

New applications of WJF process could be forming processes to obtain wing shape of aircraft or shape of some car body components

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Water jet peeningWater jet peening

WJP induces compressive residual stresses that benefit the fatigue life of materials

Recent work shows more analytical mathematical models on– Prediction of residual stresses– Prediction of feasible peening range

with different contact pressure

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Water jet in miningWater jet in mining

High pressure pulsed water jet to achieve high energy efficiency in coal mining application

Swing-oscillating jets

and the rotating jets attain better efficiencyFig . Dosco MK2B Roadheader

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Water jet in packaging Water jet in packaging industryindustry For the processing of cardboard boxes and

foams.

Advantages over conventional processing:

•High production rate

•Cheaper

•Higher quality

•Contour and straight cutting of thicker foams with high quality

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WJ in packaging industry WJ in packaging industry (contd.)(contd.)

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Water jet in food Water jet in food processing plants processing plants

contamination free cutting of frozen fish, meat, vegetables, chocolate bars and ice-creams.

High pressure pure water jet is also found effective than conventional oscillating blades in cutting sandwiches.

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WJ in food processing plants WJ in food processing plants (contd.)(contd.)

Relative comparison

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Water jet guided LASER Water jet guided LASER technologytechnologyApplication: wafer slicing Damage free dicing

Laser beam is conducted to the work piece inside a thin low-pressure water-jet by total internal reflection that takes place at the water-air interface

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WJ guided LASER technology WJ guided LASER technology (contd.)(contd.)

Advantages compared to conventional LBM:

no contamination and thermal effect, damage free dicing, low laser divergence hence high efficiency

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Temperature Temperature distributions of WJdistributions of WJ Temperature

distributions of water jet using infrared thermal imager.

Fluctuation of the turbulence can also be expressed in the infrared thermal images.

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Medical applicationsMedical applications

High powered parallel water jet

Used in wound debridement

high precision and accuracy

Far better than conventional scalpel

Trade name: VersaJet

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Other Recent Other Recent developmentsdevelopments Underwater rock cutting by water jet

– most appropriate application of pure water jets under the water level is removing of the eroded brittle non-homogeneous material.

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Conclusion:Conclusion:

1. The fragmentation of solids, e.g. mining and hydrodemolition;

2. The separation of coatings from solids, e.g. waterjet cleaning;

3. Precise cutting of solids, e.g. factory applications and medical applications.

Three main areas of research:

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Conclusion (contd.)Conclusion (contd.)

The historical trend of the advancement of waterjet technology is toward more precise control.

Machining of high hardness and thicker metals are still not found suitable by pure WJM.

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Any Query…???

Thank you

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Water Jet Machining: Recent development