The Two Types Of Hydro-Jet Cutting


Whilst hydrodemolition technology is a relatively new innovation in the world of cutting, scarification and concrete removal, its roots extend much further back than this.

Whilst some have claimed the technique can be traced all the way back to the ancient formation of rivers, it is known that sluicing or hushing has been used as far back as Ancient Rome, to hunt for gold in Dolaucothi and Las Médulas.

The modern use of the technique, with narrow jets of immense power started to be used in the 1930s, with the first patent for a hydro jet cutter filed in 1933 as an efficient, safe and less manpower-intensive way of cutting paper.

Over the nearly 90 years since, we have seen constant and consistent evolutions of the technique, and its more widespread adoption across a range of manufacturing and construction fields has emerged as a vibration-free, more environmentally friendly alternative to other demolition tools.

During that time, two main cutting techniques have evolved, both of which had been initially developed in the 1930s but have evolved considerably ever since and become the de facto standard cutting and decommissioning tool for their industry.

Both techniques follow the same principle of using a beam of high-pressure water run through a pressurised pump before being focused into a thin beam at roughly Mach 3 (around three times the speed of sound).

The main difference between the two is based on the water they use.

Pure Water Jet

Using water alone that forms a thin beam under intense pressure, pure water jet cutting has been the primary way to cut and slice soft materials since the 1930s.

The first use of it, in fact, was as a replacement for the guillotine paper trimmer, as it required less time and work to cut large sheets of paper and had more consistent results, as well as being usable to cut and create more elaborate designs.

The primary materials that can be cut via pure water jet include plastics, textiles, paper, metallic foils, very thin woods and leather, as these materials are relatively soft and can be cut to a tolerance of 0.1mm with relative ease.

It has also found use in food industry applications, as the water used for pure water jet cutting has to be the purity of water that is drinkable, allowing for water jets to be used to cut chocolate, frozen foods and cakes with a high level of accuracy.

Abrasive Water Jet

The technological development that turned water jet cutting from an essential tool in relatively niche manufacturing sectors into a versatile cutting tool for almost any aspect of construction and manufacturing is the addition of an abrasive material.

By carefully feeding sand or another small soluble abrasive into the water jet, the cutting potential of the water beam significantly increases, allowing for precise, vibration and pollution-free cutting of much harder materials.

Metals, stone and hard oxides such as silicone oxide and aluminium oxide benefit from precise abrasive jet cutting, but its true advantage can be seen in how it cuts glass and ceramics.

Before the development of water jet cutting, cutting glass panes into shape was a complex process. Most blades and saws generated considerable vibrations in the material which caused it to shatter into pieces, so it was a very careful, time-consuming task to cut.

A waterjet, which does not produce vibrations, cuts it with relative ease, allowing for the creation of larger glass panes that are designed to exact specifications, the result of which can be seen in many city skylines.

The principle also makes it effective for cutting glass and ceramics, and the lack of sparks generated also makes abrasive jets a much safer alternative when cutting in areas with flammable material, such as when decommissioning fuel tanks.

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