55. HIGH PRESSURE JET CUTTING

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Typical jet size <0.8mm faster than speed of sound.

Typical fluid is water.

Good for slotting.

Used on,

- metals

- paper

- cloth

- wood

- leather

- rubber

- plastics

- frozen food

- ceramics

Main divisions or use,

- jet cutting

- destruction of brittle materials

- separation of materials

Typical pressures are 150-1000 MPa and use 8-80 KW.

Velocities are 540-1400 m/s.

Typical fluid volume is 0.5 to 2.5 l/min.

Fluid Pressure Intensifier - hydraulics actuates smaller cylinders, that drive larger cylinders. The larger cylinders intensify air pressure.

Nozzle - internal diameter reduces 40 to 160 times to the exit tip.

The exit jet looks like,

Cutting - If the material is brittle it will fracture, if ductile or erosive, it will cut well.

Pulsed cuts can cut deeper, but feed rates must be reduced for acceptable cuts.

The fluid used must have a low viscosity to minimize energy loses,

- be non-corrosive

- non-toxic

- common and inexpensive

Water most common, but additives such as alcohols, oils, products and glycerol are used, when they can be dissolved in water (ventilation may be required).

The typical head is shown below. The orifice is often made of sapphire and ranges from 0.05" to 0.020"