Water jet machining uses a high pressure stream of water, sometimes with an abrasive additive, to cut materials. Key aspects of the process include a water jet that travels at speeds of 540-1400 m/s to erode material from the workpiece surface. Parameters like pressure, abrasive grain size, and speed affect the performance and quality of cuts. Water jet machining provides advantages like flexibility, environmental friendliness, and stress-free cuts of many materials without heat or debris. However, initial costs can be high and material removal rates are low.

1. Title
Water and Abrasive jet machining
WJM & AWJM
By
F. Salem
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2. Presentation content
*Introduction
*WJM principle
*Schematic Layout of WJM
*Abrasive water jet cutting
*Effect of WJM
*Parameters and WJM performance
*Quality surfaces and cutting parameters
*Advantages of water jet machining
*Disadvantages of water jet machining
*Conclusion
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3. Key element in WJM is a jet of water
which travels at velocities as high as 540 -
1400 m/s.
When the water stream strikes a work
piece surface, the erosive force of water
removes the material rapidly. The water,
in this case, acts like a saw and cuts a
narrow groove in the work piece material.
Introduction
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4. • The water jet machining involves directing a high pressure (150-1000 MPa)
high velocity (540-1400 m/s) to the surface to be machined. The fluid flow rate
is typically from 0.5 to 2.5 l/min.
• The kinetic energy of water jet after striking the work surface is reduced to
zero, because the bulk of kinetic energy of jet is converted into pressure energy.
• If the local pressure caused by the water jet exceeds the strength of the surface
being machined, the material from the surface gets eroded and a cavity is thus
formed.
• Water is the most common fluid used, but additives such as alcohols, oil
products and glycerol are added when they can be dissolved in water to improve
the fluid characteristics.
WJM principle
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5. Schematic Layout of WJM
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6. Abrasive water jet cutting
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7. Effect of WJM
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8. Parameters and WJM performance
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9. Quality surfaces and cutting parameters
Pressure
Grain size
Speed
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10. • Flexible production
• Environmentally friendly
• Cutting in all axes
• High speeds for various materials
• Easily adaptable to automatic contouring
• Easy programming with standard CAD/CAM systems
• Only simple fixtures required
• Small tangential forces on cut material
• No heat affected zones
• Stress free cutting
• No tool sharpening
• No dust, fumes, or gases released
Advantages of water jet machining
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11. • The starting Costs in the beginning, finding and implementing the additional
abrasive materials, like granite, to increase the efficacy of the cutter can by
very expensive compared to a simple plasma cutter.
• The abrasive powder cannot be reused because its cutting ability decrease
and it may clog on orifice of the nozzle.
• The material removal rate is low.
• Greater Thickness, Less Accuracy.
Disadvantages of water jet machining
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12. Conclusion
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• It’s good process to machining the material which we can’t
machining under high heat. So no HAZ and mechanical stresses
or operator and environmental hazards
• The thicker a material the further the stream is away from the
nozzle at its point of impact. A less consistent impact from
waterjet changes the cutting accuracy from top to bottom. Often,
the jet can spread and make more of a diagonal cut than a
straight up and down cut.