Water jet machining can reduce the costs and speed up the processes
by eliminating or reducing expensive secondary machining process.
Since no heat is applied on the materials, cut edges are clean with
minimal burr. Problems such as cracked edge defects, crystalisation,
hardening, reduced wealdability and machinability are reduced in this
process.
Water jet technology uses the principle of pressurising water to
extremely high pressures, and allowing the water to escape through a
very small opening called “orifice” or “jewel”. Water jet cutting uses the
beam of water exiting the orifice to cut soft materials. This method is not
suitable for cutting hard materials. The inlet water is typically pressurised
between 1300 – 4000 bars. This high pressure is forced through a tiny
hole in the jewel, which is typically o.18 to 0.4 mm in diameter. A picture
of water jet machining process is shown in Figure 1.
Figure 1 : Water jet cutting
, Applications
Water jet cutting is mostly used to cut lower strength materials such as
wood, plastics and aluminium. When abrasives are added, (abrasive
water jet cutting) stronger materials such as steel and tool steel can be
cut.
Advantages of water jet cutting
There is no heat generated in water jet cutting; which is especially
useful for cutting tool steel and other metals where excessive heat
may change the properties of the material.
Unlike machining or grinding, water jet cutting does not produce any
dust or particles that are harmful if inhaled.
Other advantages are similar to abrasive water jet cutting
Disadvantages of water jet cutting
One of the main disadvantages of water jet cutting is that a limited
number of materials can be cut economically.
Thick parts cannot be cut by this process economically and
accurately
Taper is also a problem with water jet cutting in very thick materials.
Taper is when the jet exits the part at different angle than it enters the
part, and cause dimensional inaccuracy.