THERE ARE TWO TYPES OF WATERJET CUTTING, PURE WATER CUTTING WHERE A HIGH PRESSURE JET OF CLEAN WATER IS USED AND ABRASIVE WATER JET CUTTING WHICH REQUIRES AN ADDED ABRASIVE, TYPICALLY GARNET.
Pure water cutting can be used to cut a wide variety of materials, often "soft" materials such as gaskets, rubber, foam and plastic. The filtered tap water is sent to a booster pump which is pressurized to (usually) 60,000 psi in a booster pump. This ultra-high pressure water is forced through a small (0.15 mm) orifice gemstone, usually made of sapphire. This allows the water beam to be focused to a fine, accurate flow rate up to 900 m/s, enabling precise cutting of soft materials.
In order to cut "harder" materials or any material containing glass or metal, abrasive water jet cutting can be used. The principle of abrasive water jet cutting is similar to pure water jet cutting, but once the fluid passes through the orifice it enters the carbide nozzle. Within the nozzle is a mixing chamber in which a partial vacuum is created as water passes. The garnet is introduced into the nozzle under the force of gravity, and a partial vacuum within the mixing chamber has the effect of dragging the abrasive into the water stream to produce a highly abrasive cutting jet. Abrasive cutting is commonly used on materials such as stainless steel, aluminum, stone, ceramics and composites.
In both processes, the head is controlled by a CNC controller, which provides extremely high accuracy and repeat ability. The CNC controller is programmed first to draw the part to be manufactured using proprietary software and then convert the picture to the G code format - the CNC language.