How Water Jet Cutting Works

Water is probably the last thing you could think of when identifying things that can cut metal. As mindboggling as it may sound, water is actually one of the most powerful metal cutting agents available. With the right pressure and abrasiveness, it can slice through almost anything from wood and plastic to rock and metal, such as steel, copper, and bronze bars. The machine that makes this possible is called water jet cutter.
machine part cutouts

What is a water jet cutter?

More popularly known as simply “waterjet”, a water jet cutter is a device for cutting hard and dense materials, such as stone and metal, using a high-pressure jet of water. It comes in two main types—“pure waterjet”, which uses pure water as its cutting agent, and “abrasive jet”, which uses a mixture of water and abrasive. Normally, a pure waterjet is used for cutting softer materials such as wood or rubber, while an abrasive jet, on the other hand, is often preferred for cutting stones and metals.

We were taught in school that water is the universal solvent. It may seem a cliché but in fact, after waterjet cutter’s discovery, we finally understood what it really means. The waterjet cutter can cut through almost anything, but industrially it is often used for cutting marble, granite, stone, metal, plastic, wood, and stainless steel. Let us find out how water jet cutting works to know what sets it apart from other cutting methods.

Parts of a Waterjet Cutter

It’s easy to think of a waterjet cutter as an ultra-modern device that comes straight out of a science fiction movie. Truth is its concept and mechanism are quite simple. Here’s to give you a good sense of the structure of water jet cutter and how it works.

The inventors of this device had three goals—1.) To generate pressure up to at least 94,000 psi (because that’s the pressure needed to make cuts on hard materials), 2.) To convert pressure into high velocity, and 3.) To control the flow of water. To achieve these goals, they have to build three components:

  • Ultrahigh-Pressure System

    – This component is responsible for creating the pressure needed to propel the water towards the material being machined. It consists of a pump, a cutting head, and a plumbing system.

  • The Machine

    – Once enough pressure is achieved, pressurized water is fed directly to a separate machine made of X, Y, Z axes (enables the nozzle to accurately create the desired cutting path), cutting head wrist axes (used for making angled cuts and minimizing taper to create precise vertical cuts), and material support catcher (dissipates the energy of the abrasive jet).

  • Control System

    – Of course, for precision and efficient flow of production, there has to be a separate system for controls. This part of the waterjet cutter consists of the programming software, operator interface, drive motors, and position and velocity feedback system.

How Does a Water Jet Cutter Work

High-speed water from the water main is pumped into the water jet and reduced into a tiny jet of stream upon passing through a jeweled nozzle. Depending on the properties of the material being machined, additives in the form of suspended grit or other abrasives may be mixed with the water. This is normally done when cutting through metal, such as titanium or steel. Softer metals like bronze and brass may require a less abrasive cutting solution.

As mentioned above, a waterjet cutter requires a control system, typically with robotics to ensure precise and accurate cuts based on the desired design and pattern. Unfortunately, there’s a handful of materials that can’t be efficiently cut using a waterjet cutter due to their brittleness. Tempered glass, for instance, shatters no matter how quickly the pressurized jet stream makes contact with its surface.

Benefits of Waterjet Cutting

There are numerous ways to cut precise designs on materials, soft and hard alike, but what sets waterjet cutting apart? Why do builders and artisans prefer it to other methods? Here are some of the reasons.

  • Low Cost

    – While it seems to have a multifaceted construction, a waterjet cutter’s design is actually pretty straightforward, and comes with inexpensive materials. It also doesn’t require special clamps, fixtures or tool changes, which is why it can be built anywhere and by almost anyone with expertise in machine construction. In effect, the cost of production and operation using this machine is much lower compared to that of other cutting methods.

  • Heat-Free

    – Some methods involve heat to make the material easier to cut. Unfortunately, heat has been known to change a material chemically, affecting its properties. The water used in a waterjet cutter doesn’t require heating, and the abrasives added are not too harsh as to severely affect the properties of the material they corrode.

  • Supports a Variety of Materials

    – Unlike other cutting machines that can only cut a few types of material, mostly soft metals, waterjet cutting can be used on a plethora of materials, even those that would be difficult to machine using other cutting techniques.

  • Dust-Free and Odorless

    – Dust formed from cutting can be extremely harmful to health when inhaled. This is why machinists are required to wear heavy protective gear when cutting metals or stay behind a protective wall. With waterjet cutting system, however, dust particles produced from cutting are immediately wet and drained with the excess water, making the process completely dust-free. There’s no strong odor as well.

Now that you know how water jet cutting machine works, you probably have an idea what its common applications are. There are many to mention apart from machining. These include removing highway marking strips, cutting logs, cutting out parts for aircraft and spacecraft, and making bronze and brass plates and sheets. Those who know where to buy copper sheets and plates know that manufacturers are already employing this latest technology in their production. Top copper suppliers, such as Rotax Metals, are among the many that do. On your next trip to a metal supply store, you can ask how the metals were cut and if they mention waterjet, you can expect their products to be top of the range.


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