A CNC waterjet cutter is an automated cutting tool that uses the principle of mechanical erosion, injecting a high-pressure stream of water (often mixed with an abrasive) to cut precisely through almost any material. It is a cold cutting process.
1. Basic operating principles
The operation of a waterjet machine relies on converting water pressure into very high speeds for cutting, which is divided into three main steps as follows:
1.1 Ultra High-Pressure Generation
High-Pressure Pump (or Intensifier Pump): This is the heart of the system. It takes filtered tap water and intensifies it to a very high pressure, typically around60,000to94,000PSI (pounds per square inch) or approximately4,000to6,480bar
1.2 Pressure to Velocity Conversion
Orifice: High-pressure water is directed through a metal tube to the cutting head. As the water is forced through a tiny hole called an "orifice" (usually made of diamond or sapphire), which is much smaller than a human hair, the laws of physics convert the water pressure into a jet of water that travels at supersonic speeds (higher than sonic ).2,500miles per hour, or about 3-4 times the speed of sound)
1.3 Cutting Mechanism
Waterjet cutting is divided into two types depending on the material:
Pure Waterjet Cutting: Used for cutting soft materials such as rubber, foam, plastic, wood or food. The high-speed water jet cuts the material by the force generated when it hits the surface.
Abrasive Waterjet Cutting: Used for cutting hard materials such as metal (steel, stainless steel, aluminum), stone, glass, or ceramics.
In the mixing chamber of the cutting head, abrasives such as garnet, a natural sand, are sucked into the pure water stream through the principle of vacuum (Venturi effect).
The abrasive-mixed water stream is accelerated and projected out of the focusing tube as high-speed "liquid sandpaper" that erode, or grinds, away material in small, microscopic amounts.
2. The role of the CNC system
CNC (Computer Numerical Control) systems are crucial in controlling the entire process to produce precise and complex workpieces:
Programming: The user enters 2D or 3D drawings created from a CAD program into the CNC system.
Motion Control: The CNC software converts the design into G-code to control the movement of the cutting head in the X and Y axes (and the Z axis or other rotational axes for 3-5 axis machines) to cut along the desired line.
Parameter Management: The CNC system controls water valve opening/closing, pressure adjustment, and abrasive feed rate to suit the material type and thickness, which affects cutting speed and edge quality.
Main advantages of Waterjet CNC
No Heat Generation: Since it is a cold cutting process, there is no material distortion (Thermal Distortion) or heat affected zone (HAZ) generation.
Material versatility: Can cut almost any material, from soft to very hard.
High precision: It can cut complex shapes with high precision and has a very narrow Kerf, reducing material waste.
