Waterjets: Abrasive vs. Pure Water Cutting
Waterjet machining is an innovative cutting method, and one of the fastest-growing processes for machining today, thanks to its ease of use and versatility. While most professionals in the manufacturing industry have heard of waterjets, they may not realize there are actually two distinct forms of this process available. Though the word “waterjet” often refers to abrasive cutting, the term actually defines a broader approach to machining – one that covers the use of both pure and abrasive jets.
Understanding the difference between the two waterjet options is crucial when choosing the right tool for your project.
Defining Pure and Abrasive Waterjets
A pure waterjet, as the name indicates, is the cleanest original form of waterjet technology. Pure waterjets work by directing a stream of pressurized water onto a material, for a precise cut. Unlike other machining solutions, the pure waterjet process is a form of cold-cutting, which removes the risk of heat-affected zones in the material – preventing it from hardening during the machining process.
The only issue with pure waterjet is that it’s limited to use on thin or soft materials; such as foil, cardboard, fabric, wood, and rubber. Alternatively, abrasive waterjet technology maximizes the benefits of pure waterjet cutting for use on harder materials.
In the 1980s, manufacturers found that adding abrasives to the water stream generated a new process for cutting, which expanded waterjet applications. Though abrasive waterjets follow the same operating principles as pure waterjets, they introduce the use of abrasive particles – such as garnet – which mix within the high-pressure stream, eroding virtually any material (of any thickness) with precision and speed. The opportunities offered by abrasive waterjets has made them an ideal choice for parts manufacturers and fabricators across a number of industries.
How Pure and Abrasive Waterjets Cut
The primary difference between pure and abrasive waterjet cutting is whether additives are mixed into the pressurized water that streams from the machine nozzle. In pure waterjets, the pressure of the water alone, when forced through a tiny orifice, is used to cut through materials like foam (and even food). In an abrasive waterjet, the water stream mixes with an abrasive when it leaves the orifice. The abrasive particles use the water as an accelerant, which allows them to erode through much harder materials.
In abrasive waterjet cutting, the water is no longer the cutting tool – instead, the abrasive particles are responsible for the machining work. The waterjet’s job is to focus those particles at the right level and speed for an efficient cut. Manufacturers can achieve faster cuts by increasing the number or speed of the particles.
The Capabilities of Pure and Abrasive Waterjets
Because pure waterjet cutting uses only water, it’s more suitable for delicate materials, such as felts and foams. The purity in the water stream prevents damage to finished components – even during detailed machining.
Abrasive waterjets are often used to cut metals, like steel and aluminum. A good rule of thumb is that if you can cut the material with scissors, you can cut it with a pure waterjet. Pure waterjets can cut through:
- Food products (like cake, chicken, or fruit)
- Thin Plastic
Abrasive waterjets can cut through:
- Thick Plastics
Which Waterjet Is Right for You?
Because they are based in the same process, pure and abrasive waterjets share many of the same advantages; including quick cutting speeds, reduction of heat-affected zones, precise cuts, reduced environmental impact, and minimal finishing requirements. Determining which method is right for your projects depends on your future business plans and operations. In terms of budget, abrasive jets cost more to operate, as a result of abrasive consumption and wear. These additional costs are worth the investment if your organization needs to cut a diversified range of materials.
If your focus is on thin or soft materials, pure waterjets will make the most economical sense. Pure is also the way to go if you’re using waterjet machines to cut food, as you need to stick to the technology in its purest form to meet with USDA standards for hygienic cutting.
What kind of waterjet cutting do you use most often? If you use both, how do you feel about the differences between abrasive and pure waterjets? Let us know in the comments below!
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