When Plasti-Fab Inc. (Tualatin, Ore.), a manufacturer of corrosion-resistant equipment for water and wastewater treatment and control, landed a contract to cut hundreds of circles out of 8,000-lb/3,629-kg, 1-inch/25 mm thick rectangular fiberglass plates, the company needed an efficient cutting solution. Tests with a handheld router yielded poor results: “It was taking us about a week to do 28 holes,” says Plasti-Fab’s CNC supervisor, Wade Oxford. When he determined that CNC routers would not be fast enough, the company turned to abrasive waterjet cutting, but faced a two-fold challenge: find a waterjet manufacturer capable of building the 14-ft by 28-ft (4.27m by 8.53m) table needed for the application and, because shop space was limited, a system that could be operated outdoors. Jet Edge (St. Michael, Minn.) got the nod because its Mid Rail Gantry system could accommodate the table size with a floor-mounted rack and pinion drive-rail motion system manufactured by ALLtra Corp. (Dewey, Okla.) combined with waterjet cutting components manufactured by Jet Edge.
Plasti-Fab installed the system under a steel awning equipped with a hoist, then added a swimming pool heater and retractable solar blanket to the waterjet tank to keep the water between 68°F and 74°F (20°C and 23°C) year-round, Oxford explains. Plates are moved into position, using the hoist and two forklifts, in about half an hour. The Permalign II abrasive cutting head, powered by Jet Edge’s 50-hp iP60-50 intensifier pump, uses a 0.040-inch/1.02-mm diameter nozzle at 50,000 psi, cutting at a rate of 65 inches/min (165.2 cm/sec). While Jet Edge waterjets can hold a positional accuracy of 0.005 inch with a repeatability of ±0.002 inch (±0.05 mm) over the entire work surface, for this project the waterjet is required to maintain a tolerance within 0.0625 inch/1.59 mm over 24 ft/7.32m — possible, in part, thanks to the machine’s automated control system. Reports Oxford, “Now we can complete one plate, or 212 holes, in four hours.”