Basic Principles of Waterjet & Abrasive Jet Cutting
A basic waterjet cutting system consists of a filtration system, high-pressure pump, nozzle and catcher. Hydraulically driven intensifier pumps pressurize water to 60,000 psi or more. Water then travels to the shock attenuator, a pressure vessel that maintains output pressure for a constant, even water flow. It is then transferred to the reservoir via stainless steel tubing to the nozzle and finally exits through an orifice, traveling at three times the speed of sound.
For abrasive jet cutting, the basic ultrahigh-pressure water-generating system also includes an abrasive hopper, abrasive metering valve, and a specially designed mixing chamber. It also includes a focusing nozzle usually called a mixing tube.
The metering valve attached to the hopper serves three functions:
- turning the flow of abrasive on and off.
- metering abrasive flow.
- purging the abrasive feed line of water when the waterjet is not in use.
Abrasive is metered through a precision disk that works like an hourglass to ensure a consistent, even flow.
The abrasive cutting head consists of a high-pressure valve actuator, valve body, nozzle body, waterjet orifice and mixing tube. The cutting head operates pneumatically with the abrasive-metering valve; when the cutting head is activated, the metering valve opens to allow abrasive flow.
When the cutting system is activated, high-pressure water flows through the orifice, into the cutting head and out through the mixing tube. Materials are cut by supersonic erosion, usually with cutting forces of about 2 lb. After cutting, a water-filled catcher tank collects the abrasive/kerf/water mixture.
Waterjet & Abrasive Jet Cutting
Waterjet and Abrasive Jet Cutting technologies are sometimes mistaken for identical processes for they both utilize a concentrated beam of pressurized water which is pumped through a small orifice or jewel head and directed towards a particular material for cutting or machining.
A pure waterjet cutting system circuit filters tap water via an inlet filtration system towards a booster pump which maintains pressure at approximately 90 psi. It is then redirected towards a reciprocating intensifier pump and pressurized to approximately 60,000 psi or more. Travel then continues through a shock attenuator which maintains a steady flow and prevents water pulsation. High pressure stainless steel tubing serves to deliver the pressurized water to the cutting head nozzle. A jewel with an orifice typically 0.004” to 0.015” in diameter then transforms the pressure to velocity resulting in a stream that travels from Mach 2 to Mach 3 speeds. Jewel heads are typically sapphire, or diamond.
Waterjet cutting is suitable for soft material such as:
- Soft Gasket
- Automotive Interiors
- Tissue Paper
An abrasive jet cutting system circuit differs from the waterjet system in several ways. Whereas the waterjet technology uses pressurized water to wear away or cut the material, abrasive waterjet technology mixes an abrasive or garnet with the stream. It is those particles instead of the water which actually perform the cutting. The circuit also incorporates the use of an abrasive hopper with metering valve, and a mixing chamber to add the garnet to the waterjet stream. Once the pure waterjet stream is created via the hydraulically driven intensifier pump and transferred out of the shock attenuator, it travels to a mixing tube in which the garnet is delivered from the abrasive hopper. The cutting head pneumatically activates the metering valve which in turn opens the abrasive flow from the hopper into a precision disc which ensures a uniform flow. It is then mixed in a carbide tube and accelerated out of the orifice or jewel. These mixing tubes can range from Low Cost Composite Carbide for rough cutting to Premium Composite Carbide for precision work. Jewel heads are typically Sapphire, Ruby, or Diamond. Once the material has been cut, the abrasive solution is collected within a water filled catcher tank.
Abrasive Jet Cutting is suitable for hard material such as:
- Hardened Steel
- Stainless Steel
Both Waterjet & Abrasive Jet Cutting technologies are capable of cutting accurate, clean edges with no heat affected zones and very little fixturing. This saves on additional tooling and post machining work. Both processes also eliminate material distortion or degradation common to other cutting methods. They require few secondary operations and can provide better usage of raw material. They are also environmentally friendly. Due to their versatility and ease of operation, Waterjet and Abrasive Jet Cutting offer a myriad of advantages to all types of businesses.
Contact ADCUT today for your Waterjet Cutting Needs!