Waterjet cutting is arguably the most versatile cutting process. The technology can be used in high performance cutting of virtually all materials, with the exception of highly brittle materials such as ceramics and tempered glass.
It uses an ultra-high pressure stream of water (for soft cutting) or contains an abrasive grit (for abrasive cutting) to cut both soft and hard materials, respectively, through a mechanical sawing motion that produces a smooth, precisely cut surface.
How Waterjet Cutting Works
Waterjet cutting utilizes the energy of a rapidly moving jet of water to erode a material and cut it. The stream of water also clears any debris for a high quality cut, and acts as a cooling agent to eliminate heat.
The process uses a stream of water at ultra-high water pressure of up to 90,000 psi to erode a narrow line in the material and essentially cut it. To achieve such high pressures, the waterjet machine uses a large horsepower motor to drive a hydraulic intensifier pump, which generates hydraulic pressure to power a small piston into a cylinder filled with water.
The size of the water cylinder is only a small fraction of that of the hydraulic cylinder. If the latter is 20 times bigger, then a 2,500 PSI hydraulic pressure can be intensified to 50,000 PSI water pressure. If the ratio is 30:1, you can achieve 75,000 PSI water pressure, and so on.
Here is the typical process for waterjet cutting:
The high pressure water is applied through a very small opening with a diameter of between 0.005 and 0.020 inches or 0.1–0.2 mm. Considering that the cut is about a hairline wide, it can cut very sharp contours with great precision. The orifice is made in sapphire or diamond to withstand the abrasive force of the water.
Pure-Water vs. Abrasive Cutting
The high pressure stream of water alone is enough to cut soft materials such as paper, leather, rubber, foam, textiles, insulation, and cardboard, among others. These materials can be cut at very high speeds, depending on how fast the cutting nozzle or material moves. Carpeting is usually cut at a rate of 15 to 30 m/min, while plastic and paper foils can be cut at 200 m/min, which makes waterjet cutting a great alternative for blade cutting.
The water used must be very pure—drinkable level—which makes waterjet cutting suitable for applications in the food industry, such as for cutting frozen fish or cakes.
But to cut hard materials such as steel, stone, aluminum oxide, glass composite, wood, plastic, or titanium, a granular abrasive (usually crushed garnet) is added to the water stream after it exits the orifice. It is the abrasive that does the actual cutting. Other types of abrasives may be used for special applications.
Since the abrasive is added at the orifice, the operator can easily switch between water-only and abrasive waterjet cutting. But keep in mind that abrasive cutting is considerably slower than pure-water cutting, usually less than 1 m/min. The speed depends on the type of material, its thickness, and the desired surface quality.
Advantages of Waterjet Cutting
Waterjet cutting offers numerous benefits compared to other cutting techniques, though it may not be the most practical choice for some materials due to its slow and expensive process.
Is Waterjet Cutting Right for Your Application?
Pure-water cutting can be used to cut most thin materials, including sheets of metal, while abrasive waterjet cutting has almost no limitations in terms of type of material or thickness.
The technology plays a major role in many industries, including:
Any industry can take advantage of the unique capabilities of waterjet cutting to produce high accuracy cuts without heat, pollution, and other negative effects associated with alternative methods. You simply need to find the right equipment (in terms of nozzle diameter, abrasive feed, and cutting pressure) for your type of material, thickness, and desired quality.
For more information about waterjet cutting, call Dwight Crane at 416-639-2638 or contact us here.
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