How Water Jet Cutting Works
The working principle of water jet cutting machine and its
Water jet cutting as the name implies makes use high
pressure water jets to cut the material. But is it possible cut
hard material like steel with water? The answer is yes. To
understand how this is possible let's learn about the working
method of waterjet machines.
Water Jet Machine Working Principle
Water jets at ultra high pressure is capable of penetrating
hard substances. You might have observed how water stream from
pressure washer removes the dirt from your vehicle at the car
wash center. In case of water jet machines the pressure exerted
is much higher. In fact the pressure is at least 30 times more
than the average pressure washers.
Typical water jet machines are equipped with waterjets with
pressure between 30,000 and 55,000 PSI (pounds per square
inch). The flow of high pressured water is channeled
through a very narrow nozzle with constant pressure which
enable waterjets to penetrate through the material and cut.
Maintaining the spray coherent is the secret of water jet
Working Principle of Water Jet Cutters. (Image
The term water jet only indicates flow of water with high
pressure. The pure water jet is enough to cute plastic and
other soft materials. However the pure waterjets alone can
not penetrate through hard materials like steel. In such cases
we need abrasive water jet machines.
Water Jet Cutting
Now let's see the actual water jet cutting process. The
above figure explains the key principle by which the machine
runs. At 50,000 PSI the water jet traveling through the narrow
orifice will have a speed of 1,700 feet per second, more than
twice the speed of sound.
In abrasive water jet machines there will be garnet abrasive
mixed in water and now we have a very thin stream of water
traveling very high speed that will rapidly erode most
materials. Since the abrasive particles will result in erosion
of work piece as well as the nozzle it is necessary to use the
orifice made out of very hard material which can resist this
erosion. Normally orifice jewel are made from Sapphire or Ruby.
The movement of the machine is controlled by computer to
precisely cut the desired geometry on the work piece.