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Transcript of Waterjet Final
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Dr. Lotfi K. Gaafar 2003
Waterjet Machining
Dr. Lotfi K. Gaafar
The American University in CairoDepartment of Mechanical
(202) 797-5355
Edited by:
Eng. Ahmed Ibrahim Hassan
Dr. Lotfi K. Gaafar 2003
Waterjet Evolution
1930s : Mining to remove stone and coal
1960s : Need to cut advanced materials foraerospace industry
1970s : First attempts to employ WaterJet to cutadvanced composites for aerospace applications
1980s: First commercial AWJ machines
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Theory
Forcing a large volume of water through a smallorifice in a nozzle causing acceleration of water
The extreme pressure of the accelerated waterparticles develops small cracks due to stream impact
The extreme pressure and impact of particles in the
following stream cause the small crack to propagateuntil the material is cut through.
Dr. Lotfi K. Gaafar 2003
Cont. Theory
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Components
Pump
Nozzle
Orifice
Control System
Dr. Lotfi K. Gaafar 2003
Components - Pump
50 100 hp electricdriven pump
Hydraulic BasedOperation
Pressures Up to 60,000psi (4000 bar)
Smooth Output
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Components - Pump
Dr. Lotfi K. Gaafar 2003
Components - Nozzle
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Components - Nozzle
Dr. Lotfi K. Gaafar 2003
Components Nozzle
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Components - Orifice
Jewel Orifice :
Diamond
0.01 diameter
Garnet AbrasiveParticles
Dr. Lotfi K. Gaafar 2003
Components Control System
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Materials
The list of materials that a Waterjet system couldpenetrate is significant.
To date, Applications have been used with:
Foam, GIO Phenolic, Steel, Armor plating,Urethane, Titanium, Kevlar, Aluminum, LinenPhenolic, Brass, Neoprene, Copper, Stainless Steel,Spectra, Fiberglass, Corrugated Cardboard, Acrylic,Ceramic Tile, Wood, Rubber, Glass, Marble and
Granite.
Dr. Lotfi K. Gaafar 2003
Surface Characteristics Variables of Cuts
Water jet Pressure
Water jet Diameter
Abrasive Material Type
Abrasive Material Size
Abrasive Material Flow Rate
Traverse Speed
The Cutting Angle
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No heat affected zone
Stress-free cutting Noresidual stresses
Wide range of materials
Environmentally friendly
No need for surface finish
No tool changing
Minimal Fixturing Required
Advantages
Dr. Lotfi K. Gaafar 2003
Cont. Advantages
Faster than any other technique
Saves Raw Material
Flexible Machining Integration
Does Not Need a Starting Hole
Ability to Cut in Any Direction
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Dr. Lotfi K. Gaafar 2003
Disadvantages
Limited number of materials can be cuteconomically
Very thick parts can not be cut with Water JetCutting and still hold dimensional accuracy
Slower cutting rate compared to both plasma andoxyfuel cutting processes
Higher entry cost
Dr. Lotfi K. Gaafar 2003
Comparison to
Other Methods
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WaterJet vs. Laser
No Heat AffectedZone
Can Cut ThroughReflective Materials
Can Cut UnevenSurfaces Smoothly
Environmentallyfriendly
Can Cut Up to 12 inhard materials (Ti, SS)& 24 in Rubber
Minimal Heat AffectedZone
Reflects on ShinySurfaces
Laser Defracts andLooses its Focus
Produces Toxic Fumes
Max. Depth 0.5 0.75
Dr. Lotfi K. Gaafar 2003
WaterJet vs. WireEDM
Can Cut through anymaterial
No Need for a StartingHole
No Heat AffectedZone
Limited to ConductingMaterials
A Starting Hole isNeeded for the Wire
Heat Affected Zone
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WaterJet vs. Milling
Excellent Use of RawMaterial
No Tool Changing
No Fixturing Required
No CleanUp isRequired
Faster
Large Amounts of Wasteof Raw Material
Frequent Tool Changing
Fixturing is essential
Requires PeriodicalCleanUp
Slow
Dr. Lotfi K. Gaafar 2003
Deciding which metal Cutting System is Best
Variables to be considered when making a decisionon the right cutting system to use :
Cutting speed Edge cleanliness
Degree of tolerance required Number and types of metal to be cut
Capital investment Operating costs Size of heat affected zone Access to secondary machining processes
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Applications
Dr. Lotfi K. Gaafar 2003
Applications
Aerospace
Automotive
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Applications
Food Processing
Dr. Lotfi K. Gaafar 2003
Applications
Electronics and PCBs
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Applications
How Accurate
We can get
Dr. Lotfi K. Gaafar 2003
Applications
Marble Industry
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Applications
Lining
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Applications
Concrete
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Applications
Aluminum
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Applications
Polymers andComposites
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Applications
Steels WithDifferentThickness
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References
www.mmsonline.com
