Waterjet cutting creates new opportunities for designers
Good product design is as much about understanding the capabilities of the manufacturing processes as it is about fulfilling the product's functional requirements. Designers therefore need to appreciate how processes are evolving, and one that is developing fast is waterjet cutting and the related process of abrasive waterjet cutting.
From the early 1970s, when waterjet cutting was first used commercially on paper-based materials and honeycomb materials for the aerospace industry, development progressed rapidly until the 1980s, when abrasive cutting was commercialized. Modern waterjet and abrasive waterjet cutting equipment is robust, reliable and versatile. Typically an ultra-high-pressure intensifier (pump) delivers water at up to 4150 bar (60,000 psi) such that it exits the cutting nozzle at Mach 2-3 (680-1020 m/s). Diamond or sapphire is usually used for the nozzle to maximise the cutting life. Where used, the abrasive material is usually garnet or olivine. While most machines cut two-dimensional (2D) profiles, others use a cutting head mounted on a multi-axis manipulator to enable three-dimensional (3D) shapes with angled sides to be cut from thicker sheet. It is also possible to mount a cutting head on a five- or six-axis robots to enable, for example, complex mouldings to be trimmed.
Waterjet and abrasive waterjet cutting are remarkably versatile. On the one hand they can cut thin paper-like materials or soft materials such as foam, rubber and food products; on the other hand, they can cut very hard and brittle materials, including hardened steel and granite. They can also cut composite materials, meat products, and carpet. Very thin materials can be cut with ease, and abrasive waterjet cutting can be used to cut up to 180 mm of concrete or 400 mm of steel. Clearly the hardness and thickness of the workpiece have an impact on the cutting speed, as does the surface finish required.
Longer life
One of the drawbacks with waterjet and abrasive waterjet cutting used to be the short life available from the nozzle and the seals in the cutting heads and intensifiers. However, developments in these areas have resulted in considerably longer lives. Intensifier seals today can easily last 1700 hours (compared with 40-50 hours for previous generations) and cutting head seals can be expected to last 2000 hours (compared with 60-80 hours). Similarly, developments in abrasive mixing units help to make the cutting process considerably more cost-effective by reducing the maintenance requirements and the costs associated with machine downtime.
Something else that helps to minimise downtime is improved diagnostics. Intensifiers such as the KMT Streamline SL-V 60 offer a touch-screen control with guided maintenance procedures, as well as remote diagnostics via the internet .
Bigger units are often used with multiple cutting heads, thereby helping customers to minimise the investment needed to operate a machine with multiple cutting heads or multiple waterjet or abrasive waterjet cutting machines.
The three-dimensional cutting capabilities of waterjet and abrasive water jet cutting have already been mentioned, but this subject is worth exploring further. Flow International Corporation has a video on its website that illustrates the potential of a five-axis robot, with examples of plates being cut while held at an angle to the machine bed, complex aperture profiles being cut into curved surfaces, a thin-walled truncated cone being cut form thick material and, probably the most impressive, a fan with 15 curved blades. The UK's Nottingham University is another organisation at the forefront of waterjet cutting. As well as working on ways to use a six-axis abrasive waterjet cutting machine to create pockets in aerospace components, the Nottingham researchers have recently developed a way to cut thin double-curvature polycarbonate with pure water.
Another way in which waterjet and abrasive waterjet cutting are starting to move away from the traditional two-dimensional applications is in the forming of blind holes.
It is well known that the two cutting processes are capable of starting a cut away from the edge of the workpiece by first piercing through the material, but some users and researchers are starting to create blind holes by stopping the flow before the hole has penetrated to the far side of the material.
Currently the challenge is to control the shape and depth of the hole, but progress is being made in this area. For product designers, it could be argued that the most significant development in waterjet and abrasive water jet cutting in the last five years relates to improved machine productivity and, therefore, a more cost-effective process. Nevertheless, the use of five- and six-axis robots also creates new opportunities, and the pocketing functions currently being developed are likely to make waterjet and abrasive waterjet cutting even more versatile in the near future.
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One of the drawbacks with waterjet and abrasive waterjet cutting used to be the short life available from the nozzle and the seals in the cutting heads and intensifiers. However, developments in these areas have resulted in considerably longer lives. Intensifier seals today can easily last 1700 hours (compared with 40-50 hours for previous generations) and cutting head seals can be expected to last 2000 hours (compared with 60-80 hours). Similarly, developments in abrasive mixing units help to make the cutting process considerably more cost-effective by reducing the maintenance requirements and the costs associated with machine downtime.
Something else that helps to minimise downtime is improved diagnostics. Intensifiers such as the KMT Streamline SL-V 60 offer a touch-screen control with guided maintenance procedures, as well as remote diagnostics via the internet .
Bigger units are often used with multiple cutting heads, thereby helping customers to minimise the investment needed to operate a machine with multiple cutting heads or multiple waterjet or abrasive waterjet cutting machines.
The three-dimensional cutting capabilities of waterjet and abrasive water jet cutting have already been mentioned, but this subject is worth exploring further. Flow International Corporation has a video on its website that illustrates the potential of a five-axis robot, with examples of plates being cut while held at an angle to the machine bed, complex aperture profiles being cut into curved surfaces, a thin-walled truncated cone being cut form thick material and, probably the most impressive, a fan with 15 curved blades. The UK's Nottingham University is another organisation at the forefront of waterjet cutting. As well as working on ways to use a six-axis abrasive waterjet cutting machine to create pockets in aerospace components, the Nottingham researchers have recently developed a way to cut thin double-curvature polycarbonate with pure water.
Another way in which waterjet and abrasive waterjet cutting are starting to move away from the traditional two-dimensional applications is in the forming of blind holes.
It is well known that the two cutting processes are capable of starting a cut away from the edge of the workpiece by first piercing through the material, but some users and researchers are starting to create blind holes by stopping the flow before the hole has penetrated to the far side of the material.
Currently the challenge is to control the shape and depth of the hole, but progress is being made in this area. For product designers, it could be argued that the most significant development in waterjet and abrasive water jet cutting in the last five years relates to improved machine productivity and, therefore, a more cost-effective process. Nevertheless, the use of five- and six-axis robots also creates new opportunities, and the pocketing functions currently being developed are likely to make waterjet and abrasive waterjet cutting even more versatile in the near future.
Interested on advanced waterjet cutting ? Did you know all about Waterjet? Subscribe and stay up to date!
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