Water Jet Machining: Recent Development

Recent development of Water Jet Machining Reyad Mehfuz

1

Water Jet Machining- recent development

Overview 1. 2. 3. 4.

Introduction General overviews Recent developments Conclusion

2

Water Jet Machining- recent development

Introduction     

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. 3

Water Jet Machining- recent development

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.

4

Water Jet Machining- recent development

Introduction (Contd.) Two steps of cutting: 2. High pressure pump or intensifier pressurizes water to produce the energy required for cutting. 3. Water is then focused through a small precious stone orifice to form an intense cutting stream.

5

Water Jet Machining- recent development

Advantages  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.

6

Water Jet Machining- recent development

Advantages (Contd.)  Sticky

materials can be smoothly cut without causing any clogging.  Dust- free process.  Minimum kerf-width  No contamination problem.  Easy automation.

7

Water Jet Machining- recent development

Mechanism

8

Water Jet Machining- recent development

Process 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.

9

Water Jet Machining- recent development

Effect of jet pressure If Jet Pressure then Depth of cut MRR 10

Water Jet Machining- recent development

Effect of stand-off distance 1 2

 1 reduction

in nozzle pressure with decreasing distance

 2 a

reduction in the jet velocity with increasing distance 11

Water Jet Machining- recent development

Effect of traverse rate

12

Water Jet Machining- recent development

Depth of cut (mm)

Effect of nozzle diameter 10 9 8 7 6 5 4 3 2 1 0

Nozzle diameter 0.08 mm

Nozzle dia

0.1 mm

Depth of cut 0

200

400

600

800

1000

Pressure (MPa) 13

Water Jet Machining- recent development

Recent Development 14

Water Jet Machining- recent development

High pressure water jet

15

Water Jet Machining- recent development

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) 16

Water Jet Machining- recent development

High pressure water jet (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)

17

Water Jet Machining- recent development

Nozzle shape

Specific waterjets consumption theefficient rectangular nozzle Rectangular are found by more for improving was found significantly reduced and the productivity surface processing techniques. greater than that of the commercial round nozzles. 18

Water Jet Machining- recent development

Nozzle materials Parameters for nozzle materials wear

 water

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

19

Water Jet Machining- recent development

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.) 20

Water Jet Machining- recent development

Water jet-cleaning nozzles Basis •Erosion rate •Erosion depth

Nozzle types

Performance

Cone Jet

Poor

Fan Jet

Good

Resonating jet

Poor

Cavitating jet

Better 21

Water Jet Machining- recent development

Water 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 22

Water Jet Machining- recent development

Water 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 23

Water Jet Machining- recent development

Water jet in mining  High

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

 Swing-oscillating

Fig . Dosco MK2B Roadheader

jets and the rotating jets attain better efficiency 24

Water Jet Machining- recent development

Water jet in packaging industry 

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 25

Water Jet Machining- recent development

WJ in packaging industry (contd.)

26

Water Jet Machining- recent development

Water jet in food processing plants  contamination

free cutting of frozen fish, meat, vegetables, chocolate bars and icecreams.  High pressure pure water jet is also found effective than conventional oscillating blades in cutting sandwiches.

27

Water Jet Machining- recent development

WJ in food processing plants (contd.) Relative comparison

28

Water Jet Machining- recent development

Water jet guided LASER technology Application:  wafer slicing  Damage free dicing Laser beam is conducted to the work piece inside a thin low-pressure waterjet by total internal reflection that takes place at the water-air interface 29

Water Jet Machining- recent development

WJ guided LASER technology (contd.) Advantages compared to conventional LBM:  no

contamination and thermal effect,  damage free dicing,  low laser divergence hence high efficiency

30

Water Jet Machining- recent development

Temperature distributions of WJ 



Temperature distributions of water jet using infrared thermal imager. Fluctuation of the turbulence can also be expressed in the infrared thermal images. 31

Water Jet Machining- recent development

Medical applications    

High powered parallel water jet Used in wound debridement high precision and accuracy Far better than conventional scalpel Trade name: VersaJet 32

Water Jet Machining- recent development

Other Recent developments  Underwater

rock cutting by water jet – most appropriate application of pure water jets under the water level is removing of the eroded brittle nonhomogeneous material.

33

Water Jet Machining- recent development

Conclusion: Three main areas of research: 1. 2. 3.

The fragmentation of solids, e.g. mining and hydrodemolition; The separation of coatings from solids, e.g. waterjet cleaning; Precise cutting of solids, e.g. factory applications and medical applications. 34

Water Jet Machining- recent development

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.

35

Water Jet Machining- recent development

Thank you Any

Q

???

uery…

36