How does water-jet cutting work?

There are almost no limits to water-jet cutting in terms of cutting material and applications. It is a very efficient and precise cold cutting process using water jet technology. High-pressure water with or without abrasives cuts a wide variety of materials without the generation of polluting heat. The cutting process is characterized by silky smooth, non-workable cutting edges and minimal kerfs. The cutting systems use high-pressure pumps and nozzles to generate the high-pressure water jet.

Water-jet cutting – A definition

Water-jet cutting is a material-removing cutting process that cuts different materials without thermal stress. It works with a high-pressure water jet with or without abrasives. Water-jet cutting is a popular alternative to conventional cutting techniques.

The basic principle of water-jet cutting

Water-jet cutting is based on a very simple functional principle. A fine jet of water hits the surface of a workpiece at high speed. It causes material removal and separates the material. To generate the required high-pressure water jet, a high-pressure pump brings the water to a pressure of up to several thousand bar and directs it to the cutting head.

Depending on the material to be cut, the water can also be mixed with an abrasive. The water with a jet diameter of 0.1 to 0.5 millimeters emerges from a fine nozzle opening at the cutting head. The blasting capacity depends on the pressure of the water and the diameter of the nozzle opening. The water jet separates the material particles near the surface and causes a stress-free cutting process without heat ingression into the material. Depending on the nature of the water jet and the hardness and thickness of the material, different cutting depths and speeds can be achieved.

Advantages of water-jet cutting

  • versatile cutting process
  • cuts almost all materials and substances
  • cuts very precisely
  • smooth cut edges and minimal kerfs
  • no reworking of the cut edges
  • no heat load on the material
  • environmentally friendly process without slag waste
  • cutting water is recyclable

Influencing factors of the cut quality

In water-jet cutting, various parameters influence the cutting performance and the cutting quality. These influencing factors are:

  • the pump pressure
  • the nozzle distance to the material surface
  • the diameter of the nozzle opening
  • the generated cutting pressure of the water jet
  • the feed speed of the cutting head

The high-pressure pump as a central component of a water-jet cutting system

Water-jet cutting systems are machine tools that separate materials with a high-pressure water jet. They consist of several components. The heart of every system is the high-pressure system with its pump for generating the high-pressure water jet. For precise and efficient cutting, the cutting system requires pressures of 1,000 to 6,000 bar, which is supplied by a powerful high-pressure pump.

The nozzle with a diameter of 0.1 to 0.5 millimeters is responsible for the speed and diameter of the emerging water jet. Further components of the water-jet cutting system are containers for the abrasive material to be added, the jet destroyer, the device for moving and positioning the cutting head as well as the control and regulation technology of the system.

Various types of water-jet cutting process

Basically, two processes can be distinguished in water-jet cutting. Cutting is possible with pure water or with hard powdered material (abrasive) mixed water.

Water-jet cutting with pure water is mainly suitable for cutting soft materials such as food, foams, papers or plastics. In the food sector, for example, it is used for cutting cheese, fruit or vegetables. Plastic materials to be separated can be foils and seals. Other materials are carpets, textiles, fibrous materials or insulating materials. The process is very environmentally friendly because it uses pure, recyclable water. The water does not pollute the food during cutting.

In abrasive cutting, the system mixes a hard, powdery material into the water jet. Materials such as garnet or corundum are used as abrasive agents. Abrasive cutting is more suitable for hard materials such as metal, steel, stone, marble, ceramics, glass, bullet-proof glass, wood, graphite or laminates. The cutting process for composites is particularly efficient.

Cutting processes in comparison

Compared to other cutting processes that use heat, mechanical pressure or plasma torches, water-jet cutting is a very gentle and precise cutting process. The silky-smooth cut edges require no reworking and the kerfs of the fine water jet are minimal.

Technology Process type Materials Reworking of edges
Water jet Erosion process = liquid high-speed sandpaper Almost all No
Plasma High temperature combustion/gas welding process using ionized gas Mainly steel, stainless steel and aluminum Mostly
Laser Melting process by concentrated laser beam Mostly steel, stainless steel and aluminum, etc. Occasionally
EDM/Burner Erosion process by electrical discharge Conductive materials only no

Water-jet cutting is an ideal solution for cutting heat-sensitive materials. It does not generate any heat during cutting and provides fine cut edges with minimal kerfs. Powerful high-pressure pumps and fine nozzles are used to generate the high-pressure jet. Even very hard or thick materials can be easily cut with a suitably dimensioned water jet with or without abrasive.

Would you like more information about environmentally friendly water-jet cutting or do you need pump technology for your system, contact URACA now.