Version 1.0, August 31, 2001, Copyright, Hugh Jack 1993-2001

55. HIGH PRESSURE JET CUTTING

 

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

 

· Typical fluid is water.

 

· Good for slotting.

 

· Used on,

  1. - metals
  2. - paper
  3. - cloth
  4. - wood
  5. - leather
  6. - rubber
  7. - plastics
  8. - frozen food
  9. - ceramics

 

· Main divisions or use,

  1. - jet cutting
  2. - destruction of brittle materials
  3. - 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,

  1. - be non-corrosive
  2. - non-toxic
  3. - 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"