By: Richard Ward, RICHEL
(TileLetter, March 1999; Asia Stone Link, Jan-Mar 1999; WJTA Jet News, April 1999)
There is a good chance something you used today was cut with water. The soles of your shoes, the dashboard in your car, possibly the food ate at lunch was cut or processed with water. Also for those of you with babies even the disposable diaper was trimmed to shape with water.
Figure 1. Single head waterjet cutting steel.
But the real inroads being made by waterjet are in the aerospace, automotive, medical, defense and machining industries where waterjet cutting is being used to shape mild steel parts up to 12 inches thick, stainless steel parts of 10 inches and "carve" intricate parts for implants in titanium (Figure 1).
As pressure on manufacturers is maintained to produce faster, better, lighter and stronger products, new materials are constantly being developed. Many of these are considered composites, being made from a series of different materials laminated together. For example, a layer of titanium and aluminum separated with a honeycomb layer made from a pheonalic, an epoxy looking type of material with fibers weaving their way through the structure, are now common.
The issue that quickly comes to mind is how to cut the laminated materials. Waterjet cutting in many cases does not see the difference between the materials in the various layers, enabling the materials to be cut quickly, efficiently and with precision.
Waterjet cutting can best be described as an accelerated erosion process under control. Water is pressurized to 60,000 psi, forced through a small orifice normally 0.003 inch to 0.016 inch in diameter, after which abrasive is added to the stream and accelerated to 2,000 miles per hour. It is this fast traveling abrasive that does the cutting on hard materials. In soft materials, only water is used.
There is no heat generated with waterjet cutting, hence the lack of any localized damage to the part as is associated with laser, plasma and oxy-fuel cutting.
Tolerances as close as 0.005 inch can often be held comfortably, eliminating the need for any secondary machining or finishing. This often allows manufacturers to use waterjet cutting to complete a project in fewer steps, saving costs and reducing turnaround time.
Figure 2. Dual head waterjet cutting steel.
Waterjet cutting is unique in that the stream does not know what it is about to cut through. It simply erodes its way through whatever is in its path. For this reason, waterjet cutting has become an extremely versatile process. Businesses operating waterjet systems are able to offer a diverse range of services, cutting virtually every material known on earth. A job shop that was limited to cutting steel with an oxy-fuel torch, with the addition of a waterjet could now offer services to businesses manufacturing wooden toys, signs, marble inlay floors for hotel and residential lobbies, custom glass designs, gaskets and complex parts in almost every steel, alloy and composite. From works of art, to intricate engineering parts in stainless, inconel and titanium, waterjet cutting is carving its way into the future (Figure 2).
The accuracy of waterjet cutting has enabled precise stone work to be produced.
A typical waterjet cutting machine for marbles and granites.
