How a Waterjet Works: The Basics
Efficient and innovative machining companies use waterjet technology to shape and cut various materials with a high-pressure water stream. The thin, versatile stream allows waterjets to be fast, accurate, and flexible – leading to clean, detailed cuts in a range of materials without a change to the material properties or the development of a Heat Affected Zone. For companies that thrive on efficiency, waterjets include a quick set-up time, speedy cutting, and highly-controlled cutting accuracy.
Today, we’ll be looking into the technology behind waterjets, and how they work to deliver a precise result — no matter the task. From the parts within the waterjet system, to how those components work throughout each step of the process, this article will provide a comprehensive look at one of the most popular cutting techniques on the market.
Step 1: Setting Up the System
Waterjets manufacture components to exact specifications, which requires the use of a computerized system responsible for following a design. Technicians place a client’s material on a bench top unit beneath the waterjet nozzle, and during the cutting procedure, that material will either move to facilitate a fixed head, or the nozzle itself will move to follow a pattern. Most moving waterjet heads use a Computer Aided Design program for enhanced accuracy.
When used properly, waterjets can cut through:
- Stainless Steel
Step 2: Creating the Stream
Waterjets use water forced through a tiny hole, known as the “jewel” or “orifice”, to concentrate extreme pressure over a small space. The speed at which the water moves through the orifice creates a high-velocity jet. Creating this stream involves two primary steps:
- The intensifier or pressure-pump pressurizes water at levels of up to 60,000 PSI. The water moves into the system through a filter and booster pump. The filtering process is crucial, as water must be clean before it reaches ultra-high cutting pressure to protect components from damage. A water-treatment system removes harmful minerals from the water.
- Secondly, the filtered water flows through the small orifice to create the cutting stream. Direct drive or intensifier pumps can create the high-pressure required for cutting. Some machines use hydraulic oil pressurized at 211kg per square centimeter to power a piston.
The cutting stream can move at a velocity of Mach 3 – three times the speed of sound – depending on the water pressure. This process is applicable to both pure, and abrasive jets.
Step 3: Adding Abrasive Material
While pure waterjets use the stream of water exiting the orifice to cut through materials like foam, fiberglass, or soft rubber, they’re not effective for cutting harder materials. An abrasive jet works much like a pure waterjet, but as the stream of water leaves the orifice, an abrasive material such as garnet, mixes into the stream. The water beam accelerates those abrasive particles to speeds fast enough that they can cut through much harder materials. The resulting jet moves through a “mixing” or “focusing” tube to create a far stronger cutting mechanism.
Waterjets can use various abrasive materials, including diamond, corundum, garnet, and olivine – so long as the particle size is between 0.2 and 0.5 mm. Usually, the machine stores the abrasive substance in the pressurized hopper before it travels into a metering assembly which controls the level of particles fed to the nozzle.
Step 4: Making the Cut
Once the component design is integrated into the waterjet cutting machine through the use of CAD software, the device can program tool paths that map out the cutting process. Following the cut, the residual energy from the cutting stream dissipates into a catcher tank, which stores spent abrasive and kerf material.
In some circumstances, professionals fill catcher tanks with materials like ceramic – designed to slow the jet and reduce the chance of damage to floors and underlying fixtures.
Using a Waterjet
Waterjets are effective and environmentally friendly processes for machining that create precise, clean results, without giving off hazardous waste or vapors. As you can see above, the process for setting up and using a waterjet is simple enough for a professional to follow, assuming he or she has the right training and equipment.
If you’ve used waterjet cutting before, how did you find it compared to other machining practices? Do you have experience using a waterjet machine yourself? Let us know in the comments below.
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