What is Waterjet Cutting?

Waterjet cutting is a relatively new innovation that enables precise and inexpensive cutting of a wide variety of materials. The principle behind a waterjet is simple, but surprising nonetheless. As the name implies, a jet of water exits an orifice at approximately three times the speed of sound. The intense pressure of the narrow stream allows the water to cut virtually any material placed in front of it.

While waterjets can cut almost any material, they are primarily used to cut slabs of plastic, aluminum, steel, tile, and stone. Sometimes abrasives, such as garnet or sand, are added to the water to improve cutting efficiency. Some waterjets can cut steel up to 12 inches (15 cm) thick!

There are many waterjet cutting systems available, but most contain a similar set of components. At the heart of the system is a pump that increases the water pressure in the tank to 4,200 kg/cm2 (60,000 psi). The material to be cut is placed on a large table. A computer-controlled robotic arm or X-Y system controls the flow of water to cut the desired shape. The water stream is very narrow (typically 0.03 inch or 0.75 mm), which allows the waterjet to cut details that are impossible with traditional cutting tools.

Waterjet systems are usually computer controlled so that cutting instructions can be generated using digital drawings. Although the cuts are complex and precise, water jet cutting is often less expensive than traditional cutting methods. Another benefit of this type of cutting is that negligible heat is generated during machining, thus protecting materials sensitive to this stress. One obvious downside, however, is the water itself. Wood, paper, and some fabrics are not acceptable because they are moisture sensitive.