U.S. Granite Robotics offer the RoboCut, a robot with a combination waterjet/saw head for cutting stone.
Waterjet cutting has been a specialty technology used in a wide variety of industries since 1971. Within 20 years, major advances in waterjet technology were introduced that have caused this technology to become extremely popular for machine shops.
This technology has given thousands of manufacturers the opportunity to expand and grow their businesses by adding waterjet systems as an alternative cutting solution to conventional machine tooling methods.
Waterjet machinery is fast, flexible and accurate. It can be easy to program and is suitable for use in quick fabrication or high-volume production. Shop owners and manufacturers use the technology of ultrahigh pressure water being funneled through a small diamond orifice to form an intense waterjet cutting stream. The jet stream moves at a velocity of up to 2.5 times the speed of sound or up to 60,000 psi.
The waterjet process can cut intricate patterns on a variety of surfaces including steel, aluminum, titanium, brass, marble, stone, granite, glass, foam, paper, food and much more. Unlike machining or grinding, waterjet cutting does not produce any possibility of dust or harmful particles being inhaled. Waterjet cutting eliminates the need to sharpen tools and avoids vapor, dust and smoke.
The kerf width in waterjet cutting is very small and very little material is wasted. Like any computer numeric controlled machine, an operator can program the dimensions of the part into the control station and the waterjet will cut the part out exactly as programmed.
Waterjet system cutting can be faster and cheaper than drawing detailed prints of a part and then having a machinist cut the part out. By utilizing a digital cutting system you are able to import a simple CAD drawing and layout the drawing directly onto the material, this process is very quick and efficient, comparing this to the same work done by hand it would roughly take 10 times the amount of time and labor to layout everything and start cutting. Over time you will see great results in terms of increased production and less labor involved to accomplish the common goal. Depending on the labor savings you can see results right away.
Waterjet cutting does not leave a burr or rough edge and eliminates other machining operations such as finish sanding and grinding. Waterjets are much lighter than equivalent laser cutters used in other industries and, when mounted on an automated robot, reduce the problems of accelerating and decelerating, using less energy to perform a specified task. This allows for less pressure on the arm making the overall life application more durable.
Waterjets have the ability to cut material without interfering with the materials structure as there is no “Heat Affected Zone”. Reducing the effects of heat allows materials to be cut without destroying their natural elements. There are two main factors to consider when determining the size of the waterjet system your shop will require: water volume and pressure (with waterjet systems the typical pressure is 60,000 PSI). By increasing these two factors, cutting can be faster and have cleaner edges. With this in mind, there are three main variables which help determine how much water and pressure is needed, and in turn, which system is best for an application.
Type of material: The cutting speed depends on the material and density of the material, if you have a material that is very dense you have the option to lower the speed so you don’t crack the material. Thick materials (whether hard or soft) require larger streams of water that have greater velocity and more energy to cut over a long distance. Harder materials with dense structures also require higher pressures.
Cut speed required: Cutting faster, extremely important for higher margins and high production environments, is possible by increasing both water volume and pressure. If the surface is durable enough you can run the waterjet at full capacity. With a properly trained operator, waterjets are very safe and accurate whether you are cutting at 10,000 PSI or 60,000 PSI.
The quality of the inlet cutting water supply is one of the most important factors affecting component life and performance for waterjet systems. The water required to run through the waterjet needs to have quality standards that don’t contain impurities such as calcium, iron, alkalinity and magnesium. Most companies offer free water testing before you purchase a waterjet to ensure the cleanliness of your current water supply. It is recommended to have fresh filtered water to maximize the performance on the waterjet. The water used for the hydraulic cooling system needs to be at a consistent 60-70 degrees to ensure proper cooling.
It is recommended to have spare parts on hand especially for consumable parts that wear fast on a waterjet such as nozzles, focusing tubes, garnet, etc. If you are in the market for a waterjet, make sure you do your homework on the company, check references, ask for availability of spare parts, find out if a technician is close to your shop location and most important of all is customer service. Some waterjet manufactures offer full training that I would personally recommend to anyone looking to purchase a waterjet. At the training facilities you learn how to maintain the machine on a monthly basis, how to operate the machine, how to repair/replace parts when needed and overall get a complete education on the whole waterjet process.