Waterjet Cutting 101

Having one tool that cuts everything from tissue paper to metal to ceramic used to be a shop floor dream. The evolution of waterjet technology has not only made such versatile cutting possible, it’s becoming more common and even preferred to use waterjets on everything from composites to food. Considering their impressive power and capabilities, waterjets are surprisingly simple to understand and implement.

What is waterjet cutting?

Waterjet cutting is a supersonic, liquid erosion process. It’s supersonic because the velocity of the water streaming from the cutting head of a waterjet can be up to four times faster than the speed of sound.

The water “cuts” by compressive shear or, in the cased of abrasive jet cutting, by eroding the material it is targeted onto. Unlike other cutting technologies such as plasma or lasers that involve heat, a waterjet avoids thermal stress by focusing high-pressure water into a high-velocity stream to erode material away.

For complex cuts and shaped parts, an articulated robotic arm can maneuver the waterjet cutting head with precise positioning and velocity control.

How long has waterjet cutting been used?

The origins of waterjet cutting can be traced back to mining in the 1800’s when water was used to wash blasted areas. In the 1950s a Swedish inventor filed a patent for using a jet of fluid for cutting plastic and semi-plastic masses, and pure waterjet was created by a forestry engineer to cut lumber. More patents for liquid jet inventions were filed in the ʼ60s, with high-velocity nozzle inventions appearing in the 70’s. The addition of abrasives came next in the 1980’s.

Interest and demand for waterjet from various industries continues to increase while related software and robotics gain sophistication and acceptance. Waterjet technology is evolving from a niche device required for special cuts to an essential, versatile, precision cutting tool.

Why use robots with waterjets?

Robotics allow more degrees of freedom than traditional 2- and 3-axis CNC. With an articulated robotic arm, the waterjet stream can be directed and controlled at any angle, providing outstanding capabilities and adaptability for many industries.

What are typical applications for waterjet cutting?

Waterjets can not only slice, but also drill and cut shapes, and cut flexible material without damaging it. This versatility makes waterjets ideal for applications ranging from cutting tissue paper, diapers and baked goods to shaping automotive interiors.

Where is waterjet the best option for cutting?

While waterjet cutting is extremely versatile, it can’t be used for everything. Tempered glass can shatter after being cut with a waterjet. If speed is a priority and heat isn’t a concern, then laser or plasma cutting may be a better option than waterjet.

When evaluating cutters and comparing plasma, waterjet and laser, it’s important to look at the total cost of ownership. Although waterjet cutters can require a high initial capital expenditure and ongoing operating expenses including labor and abrasives, they offer high precision and quality in addition to the ability to cut almost anything. For applications that require tight tolerances and no thermal effects, waterjet is the clear choice.

What makes a waterjet system?

A waterjet system is made up of three main components:

• A water system that pressurizes the water and then focuses the stream through the cutting head.
• A cutting machine with multiple axes and a holding/positioning mechanism for the piece being cut. Cutting machines range from tabletop devices with an X/Y axis cutting head to robotic arms with 6 degrees of freedom. Additionally, by adding more robots, and thus, more axes to the machine, you can further enhance efficiency and reduce cycle times.
• A software-driven controller that moves the cutting machine and starts and stops the water system. The program takes a drawing from a computer-aided design (CAD) program and has an interface that allows a user to add start and stop locations, direction, and velocity information for the waterjet.

How can waterjet cut metal?

Originally, waterjet cutting used pure water only, and pure water waterjet technology is still used on softer materials such as tissue paper, diapers, and plastics. To erode hard materials such as stone, ceramic, metal, and glass, abrasive waterjets are used. Abrasive waterjets propel garnet particles into the water stream.

In addition to the versatility and precision offered by waterjet technology, it offers the added benefits of environmental friendliness and safety. Waterjet cutting doesn’t use or create any hazardous materials or fumes, and it’s not explosive.  For companies with sustainability and safety concerns, waterjet is an excellent option.