And the Winner Is… Water!
Advances in abrasive waterjet cutting make for less waste, more haste when it comes to producing parts.
Editor’s note: This article appears in our July 2009 issue.
Tool Technologies by Van Dyke LLC hosts engineering open houses throughout the year.
By Howard Van Dyke
Water carved the Grand Canyon from solid rock. Took it awhile, but water got the job done.
Imagine if you could harness and control that same sort of erosive power to the tune of 55,000 pounds per square inch – about 1,375 times more psi than your typical garden hose – to make precision parts for prototypes and mass-produced goods.
Abrasive waterjets have been in use since the early 1980s, cutting virtually any material that can withstand getting wet. The abrasive waterjet’s cutting power is its high pressure mixed with a finely crushed natural stone media, typically garnet.
Abrasive waterjet machining is the most versatile machine tool used in prototyping and manufacturing today. From one-piece prototypes to 20,000-piece extreme tolerance part runs, this technology can out-perform conventional machining methods.
Unlike plasma or laser cutters, abrasive waterjets cut without altering a material’s inherent structure because there is no “heat-affected zone” or HAZ. Abrasive waterjets allow you to “nest” single or clusters of parts together, increasing inventory efficiency and reducing scrap.
On top of that, waterjets are eco-friendly. They produce no hazardous waste, reducing disposal costs. They can cut large pieces of reusable scrap material that might have been lost using traditional cutting methods. Waterjets eliminate airborne dust particles, smoke, fumes and contaminates from cutting materials such as asbestos and fiberglass, greatly improving work environments and reducing potential exposure-related health problems.
Waterjets use very little water, about a half gallon to one gallon per minute depending on the 
size of the cutting head opening. Waste water can be recycled using a closed-looped system, but it’s usually clean enough to filter and dispose down a drain.
And the garnet abrasive is a non-toxic, natural substance. It can be used in other products and finishing processes, or properly disposed of at landfills to help put some solid mass around those aging diapers already in the ground.
Our shop uses a computerized abrasive waterjet cutter built by Kent, Wash.-based Omax Corp. We make parts for independent inventors, small firms and major research and development divisions.
Omax machines top out at 55,000 psi. “Anything higher than that,” says Dr. John Olsen, Omax’s vice president of operations, and “the high-pressure components are subject to metal fatigue.” He notes some companies sell waterjet cutters boasting as much as 90,000 psi, “but you have a big trade-off on productivity and maintenance expense.”
Faster computer processors have increased mathematical computations, making more intricate waterjet cutting possible. The machine’s computer software and cutting model calculates the path the machine must take to yield the geometry and surface finish customers request.
Our machine computes more than 1,000 calculations per linear inch of travel. This produces a uniform surface finish on the part regardless of the geometry. We’ve found we’re able to cut pieces at higher tolerances and to within nearly perfect specifications.
With waterjet cutting, you don’t have to tool machines to stamp parts, which is costly and time-consuming. Likewise, if you have to change something during production, you can “edit” without having to re-tool.
In the end, waterjet technology can offer a cleaner, faster and better way to get your parts made and your products on the market.
Howard Van Dyke is the project engineer at Tool Technologies by Van Dyke LLC in Milford Center, Ohio 43045. Phone 937.349.4900. Visit www.tooltechohio.com
