Is it possible to use water for cutting? And if so, which materials?
Questions such as the ones mentioned above arise spontaneously when confronted with industrial processes such as water cutting.
It is certainly well known that a strong concentrated water jet can cause deformation and even compression if it acts on materials such as plastics, foams, and cellular compounds.
On the other hand, it may be difficult to imagine using a water jet as a cutting tool on typically harder and more resistant materials such as metal or stone. However, it is possible, to the point that waterjet cutting technology has quickly established itself as one of the best solutions that can be adopted in the field of industrial processing.
Waterjet cutting: 3 advantages over traditional cutting techniques
The waterjet cutting technique is similar to die-cutting: there is no die, of course, but a very powerful water jet, which can reach pressures of 7,000 bar. This solves the problems associated with more rigid and compact materials.
These materials cannot always be processed by die-cutting. Their thickness is greater than the dimensions that die cutting can traditionally handle.
In comparison, waterjet cutting offers three very important advantages:
-The absence of costs related to the adjustment of the tool for each specific machining operation;
-The cooling action of the water jet, which eliminates heat from the workpieces;
-The greater durability of the cutting tool, which is not solid and cannot wear out or become dull after a certain number of operations. Thus, it is not necessary to replace or sharpen it as would be the case, for example, with a blade or a drill bit.
Having clarified what the waterjet cutting technique is and what its main advantages are, we’ll now explain how it works.
You can also learn more about the subject via the flowwaterjet.fr website.
Waterjet cutting: how it works
The basic principle is the following: the cutting is obtained by means of the compression exerted by a continuous flow of water mixed with very fine abrasive granules. This water, drawn at very high pressure by a concentrated nozzle, crushes on the structure of the metal, which starts to crumble in the end.
In effect, the power of the jet exerts a disruptive action while the abrasive inside the jet is pumped at a very high speed, etching the material to be cut.
The result is an effect very similar to that obtained after the action of an abrasive disc, with the difference that it is not solid (except in part). On the other hand, it has a certain plasticity that does not wear out and does not produce high heat or burrs.
The action of the water jet: a powerful shock wave
The tool used in the cutting technique is a kind of injector (also called a cutting head) which receives at its inlet a very high-pressure water flow coming from an amplifying pump; this one pushes it through very resistant metallic pipes.
Typically, the tool is self-aligning thanks to a precise control operated by a digitally adjustable control unit acting on a multi-axis motorized system.
The water pushed into the injector is literally ” pushed ” through a calibrated conical nozzle (otherwise known as a ” focuser “) which increases its speed by narrowing the jet at the same pressure. Thus, the water, possibly mixed with granules, escapes at up to four times the speed of sound and generates a very powerful shock wave that hits the workpiece.
To get an idea of the force exerted by the water jet, consider the following equation: The pressure of 7,000 bars corresponds to 6,908 kg/cm2, and the concrete used in construction “only” supports 325 kg/cm2!
This virtual blade can cut almost any material, metallic or non-metallic, in any shape and up to a thickness of 300 mm.
To resist the abrasion that can be caused by the addition of granules, the injector is made of extremely hard materials such as synthetic diamonds.
Waterjet cutting: a versatile and precise technique
Waterjet cutting technology is currently the most versatile machining process in the industry, as it can be applied to a wide variety of materials and machining operations. It is also an easy-to-implement technique that:
-Does not require additional machining, such as removing burrs caused by twist drills;
-Does not cause mechanical deformation;
-Does not cause thermal deformation, typical of machining with traditional tools or thermal cutting;
-Guarantees high precision, since the pressurized water jet can have a diameter as small as 1 mm.