High Pressure Water Blasters
The idea of firing a jet of water under considerable pressure is not a new idea, as shown by the fact that this principle is the basis behind the operation of any ornamental fountain or water cannon (ranging from the near-industrial ones used by the army and police to the most basic of hand held water pistols). The same principle is also used for the propulsion of jet skis and many other types of water vessels. However, in recent years the practise of ‘water jetting’ (the pressurising of water and expelling it whilst putting it under an even greater degree of pressure) has started featuring prominently in the world of industry, most notably in the form of the high pressure water blasters used in the processes of water jet cutting and water jet cleaning.
Cutting utilises same principle as all other processes involving high pressure water blasters in that a jet of water is fired at a very high speed towards a material which it then cuts through. The process is almost exactly the same as that of water erosion which is found in nature, only greatly accelerated and concentrated. Due to the fact that a water jet cutter is capable of slicing through any material, it has become increasingly popular in the world of industry, with the process being found in a number of industries ranging from aerospace to mining where it can be used for rearming, carving and shaping as well as cutting.
Cleaning (also known as water jet stripping and water blast cleaning) is yet another process which has become increasingly popular in the world of industry (being frequently used in the heavy equipment, automotive and aerospace industries) as a means of removing undesired contamination, materials or coatings from surfaces of work pieces.
The process of water jet cleaning removes the undesired coatings through the use of one of two methods: erosion or delamination. Erosion is used for the removal of hard coatings (such as carbide thermal spray coatings and metal). In this process, a special nozzle is used to help break up the jet of water into small droplets which then impact the surface of the coating, causing it to erode whilst still leaving the substrate underneath intact. In the process of delamination (which is usually used on softer coatings), however, the water nozzle keeps the jet of water intact, thereby allowing the jet to penetrate the surface of the coating and impact the substrate before spreading out to delaminate the coating at the bond interface.