Waterjet technology represents one of the fastest growing areas of manufacturing in the world — thanks to the fact that it’s highly versatile, effective, and precise. Capable of cutting through almost any material with extreme accuracy, waterjet cutting is a fabrication process that can provide essential solutions when other methods — such as lasers, and traditional cutting — simply aren’t applicable to the project at hand.
At a basic level, a waterjet is a cutting tool used to shape materials with a high-pressure stream of water. If the water stream includes an abrasive, it becomes more powerful, and can cut tougher materials.
At a more detailed level, we’ll outline how waterjet technology works on a deeper basis — explaining how each essential component in these innovative machines work together to create intricate, accurate cuts.
Defining the Cutting Capabilities of Waterjet Technology
Before we cover the components of a waterjet machine, it’s important to note that there are two main types of waterjet machining available — and the differences between these types distinguish what each machine is capable of.
- Pure Waterjet Technology
Pure waterjets cut softer materials; such as foam, rubber, leather, textiles, and even cakes and vegetables. Though these machines contain many of the same components as their counterparts, they do not include the abrasive materials in the water stream. In a pure waterjet, the stream can move at a velocity of up to 2.5 times the speed of sound.
2. Abrasive Waterjet Technology
Abrasive waterjets shape harder materials that cannot be cut using water alone. In these machines, engineers replace the water nozzle of pure jets with an abrasive cutting head. The high-velocity stream draws the abrasive into a mixing chamber, to produce a powerful blast of erosive water. Abrasive jets can cut various materials; including sheet metal, aluminum, stainless steel, and concrete.
The Components of Waterjet Machines
Though abrasive and pure waterjet machines differ in cutting capabilities, the primary components that work together within the machine remain largely the same. In both circumstances, waterjet cutting involves the movement of water at extremely high pressures through a small diameter nozzle.
Most waterjet systems contain the following components:
- High pressure pump — This pump generates a flow of pressurized water for cutting.
- Articulated cutting head — This multi-axis cutting head is capable of permitting various angled cuts, and precise vertical machining.
- Abrasive nozzle, or pure waterjet nozzle — Depending on the purpose of the machine, the nozzle either works as a medium through which to mix water with abrasive substances, or simply a focus point for a pure water stream.
- Catcher tank — Filled with water, the catcher tank dissipates the energy of an abrasive jet, after it cuts through the material.
- Abrasive hopper — Only used in abrasive waterjet machines, the hopper controls the flow of granular abrasive into the nozzle.
- Traverse and control system — This precise system accurately moves the nozzle through the correct cutting path. In some instances, this will come in the form of an advanced, PC-based motion controller.
The Waterjet Cutting Process
With the components outlined above all working harmoniously, waterjet machines cut materials using the same principles as natural water erosion — only at a much more concentrated, accelerated level. Water lands forcefully upon the surface of a material, in order to loosen and wash away unwanted particles.
The standard waterjet works through a process of important steps:
Step 1: Gathering Water
The process begins when a large electric pump draws water into the system, at a high pressure rate. The machine stores the water within a heavy-duty intensifier assembly, to amplify the existing pressure.
Step 2: Increasing Pressure
Inside the intensifier system, the water pressure increases to a level that usually falls between 20,000 and 55,000 psi (pounds per square inch). This increase in pressure comes from pistons within the system.
Step 3: Sending Water through an Orifice
The ultra high-pressure water is then drawn through stainless steel pressurized piping, into a cutting head — where it is focused through a sapphire, ruby, or diamond orifice between 0.010″ and 0.015″ in diameter. This turns the stream of water into a fine needle of cutting power.
Step 4: Adding Abrasive
In an abrasive waterjet, the water passes through a mixing chamber, where the pressure of the stream draws abrasive into the water. The mixture of abrasive and water passes through a ceramic mixing tube, before exiting the nozzle as a stream of high-power cutting particles.
Step 5: Exiting the Cutting Head
Either with or without abrasive, the water (or water mixture) exits the cutting head through a focusing tube, at speeds that can reach up to Mach 3 (three times the speed of sound).
The end result of this precise process? Depending on your project, it may be a set of artistic geode bookends, a meticulously-designed and fitted motorbike helmet, or a row of perfectly sliced pastries.
For centuries, the human race has turned to the powerful forces of nature to achieve feats of engineering and creation. From sawing logs, to milling flour, weaving textiles, and even generating power, water has long proven to be a versatile and useful ally in the manufacturing world.
Water can easily wash away hills and shape mountains, through erosion — and from this natural process, the idea to create an accelerated machining solution emerged. From the promising waterjet solutions of the past, to the innovative and comprehensive waterjets used across the world today, there’s almost nothing water can’t do.
Waterjet cutting is one of the fastest growing methods of machining in the world — capable of profiling a huge array of materials. Let’s take a look at how this precise cutting process got to where it is today.
Where Waterjets Began
Waterjets officially emerged for the first time during the early 1800’s — when coal miners from the Soviet Union and New Zealand used pressurized water, diverted from streams, to remove loose debris and coal. During the Gold Rush of the mid-late 1800’s in California, the same concept was put to use; pressurized water excavated gold from soft rock, and directed it downstream for pan-wielding miners. Though hydraulic mining isn’t the primary function of waterjet machines today, it marks the start of a series of inventions that lead to water’s current role as an industrial cutting device.
In the 1930’s, waterjet technology found a purpose cutting materials like paper, using a jet-stream technique created by Leslie Tirrell and Elmo Smith. After time, innovators began to see the benefits of adding abrasives to a waterjet stream, in an attempt to cut harder materials. While the initial lifespan of abrasive waterjet nozzles was too short to be commercially viable, these new designs prompted the creation of new mixing tubes and materials, designed to make waterjet machining stronger — and more reliable than ever.
The Evolution of High-Strength Waterjets
In the post-war era, researchers and manufacturers across the globe continued to seek new methods of efficiently cutting materials. In the 1950’s, a forestry engineer called Dr. Norman Franz experimented with ultra-high pressure water systems, in an effort to cut trees to lumber. His experiments showed that abrasive waterjets could effectively cut harder materials.
In the mid-1960’s, research into traditional waterjet cutting by G.L. Walker, and S.J. Leach helped to determine the ideal shape of waterjet nozzles. The 1970’s saw the invention of crystal waterjet orifices — created by the Bendix corporation — which helped develop the very first mainstream waterjet cutting system on a commercial level.
This new waterjet system could achieve pressures of up to 60,000 PSI — meaning that a jet of approximately 0.1mm diameter could slice and dice anything from food products to paper. Though these waterjet machines were expensive — and required a lot of maintenance — they were still regarded as more cost-effective than traditional methods of cutting softer materials.
The Waterjet Today
By the end of the 1980’s, the Boride corporation had developed mixing tubes composed of a ceramic, tungsten, and carbide compensate. These carefully designed tubes could withstand the erosive pressure of abrasive waterjets, transforming the unreliable process of the 1930’s into a viable solution for the future of manufacturing.
Flow International, Inc. became the first company to sell a waterjet machine to an automotive manufacturer — and others quickly followed suit. Over time, intensifiers emerged to develop a more consistent pressure within waterjet machines; while new components allowed experts to measure the amount of abrasive they were using. Each new innovation has made waterjet technology more affordable and reliable within the manufacturing industry — allowing its popularity to grow and blossom.
The waterjet’s capabilities are still evolving, as diamond orifices replace sapphire orifices, and standard nozzles transform into composite carbides. The manufacturing industry is continually seeking to make the process more precise, reliable, and accessible — when it comes to sheer power, we may just be floating on the surface of what water can do.
Do you have any predictions for the future of waterjet cutting? Let us know in the comments below!