Public Sculptures Come to Life with Waterjets

Waterjet Cutting Technology Dramatically Improves Quality of Parts

For more than three decades, artisan Ron McPherson has produced limited edition graphics and nationally recognized works of art ranging from hand lithographs in the National Gallery of Art to prints for famous artists such as Roy Lichtenstein.

After starting his own company in 1974, McPherson’s print work gradually evolved into sculpture work. To create sculptures, which ranged from a 10-foot metal chair for Yoko Ono to public artwork, McPherson relied on a plasma cutter. However, the plasma cutting process left a damaged thermal edge that required secondary finishing such as edge grinding or polishing to remove.

“Plasma left significant thermal damage on the edges which needed to be ground out,” says McPherson. “Welding codes of public works require removal of 1/8 inch of thermal damage caused by the plasma which added significant time to projects.”

Through the years, McPherson had seen parts cut with waterjets and started investigating how they might work for his artwork. After extensive research, McPherson realized the benefits of abrasive waterjet cutting and purchased a 6’ x 12’ Integrated Flying Bridge from Flow International Corporation.

What is abrasive waterjet cutting and how does it work? Using a high-pressure pump, water is forced through an orifice at pressures up to 60,000 pounds per square inch (psi), with a garnet abrasive entrained in the waterjet stream. The water and garnet abrasive mixture combine to quickly and precisely cut materials ranging from metal to plastic with a high level of accuracy. Since abrasive waterjet cutting is a cold-cutting process it leaves no thermal damage on edges of parts, saving project time by eliminating secondary finishing of parts. The waterjet’s fine jet stream also cuts at a tight tolerance enabling a high level of accuracy on finished parts.

“The accuracy of waterjet cutting is phenomenal, plasma can’t even come close to it,” says McPherson. “The finish work and ease of waterjet cutting is amazing. The tolerances make parts fit together much better than before when I had to grind out the thermal damage caused by plasma.”

Since implementing the waterjets, McPherson has been able to cut materials he couldn’t have cut with a plasma machine — and with far superior edge quality. One example is McPherson’s work on artist Jonathan Borofsky’s “ I Dreamed I Could Fly” project at the Toronto Airport , which consisted of five flying figures measuring 25 feet long. The sculpture used a variety of materials including 5/8” aluminum for the framework, which holds the plastic flying figures. McPherson used the waterjet to cut the aluminum plate for the sculpture’s frame. He also used the waterjet to cut rivet holes into the aluminum, which hold the sculpture together — all work he would not have been able to produce using the plasma machine.

“The ability to cut plastic and holes speaks to the diversity of the waterjet,” says McPherson. “The waterjets helped me eliminate error in drilling the holes necessary to position the parts accurately for the sculpture. And, using the UltraPierce feature of Flow’s waterjet allowed me to cut the plastic without fracturing the material, which consisted of a lexan and acrylic material. Using the waterjets allowed me to save time on this project and dramatically improve the quality of the parts I cut. Also key was the accuracy of the layout from the design on my computer to the waterjet cutting process which allowed me to fit isolated parts together when it came time to build the sculpture.”

McPherson’s work on artist Jonathan Borofsky’s “Dancers” project in Denver , Colo. involved fabricating 60 foot tall figurines using 16 inch diameter 1 inch wall pipe, which was used to hold the outer fiberglass shell used to complete the structure; similar to building the hull of a boat, McPherson explains. Since this project was a public artwork, the ability to complete the structural element so that it met code requirements was critical.

“There was about 300 pages of structural code that had to be met,” explains McPherson. “One of the most important parts of meeting code requirements for public structures is edge quality; there cannot be any thermal damage on the structure at all. The waterjets cut with no thermal damage which helped us meet code for the project.”

In short, McPherson has been amazed by what the waterjets have enabled him to do. “I’ve been able to achieve more than expected with the waterjets. The tight nesting capabilities, high quality of edges, and accuracy of cuts have exceeded my expectations for what the machine has allowed me to do.”

Story used with permission from www.flowcorp.com