How Waterjet Technology Works
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.
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