Waterjet technology cuts to the chase

Dec. 1, 1998
Ultrahigh-pressure waterjet cutting is both economical and versatile.

Ultrahigh-pressure waterjet cutting is both economical and versatile.

The Flow waterjet system is at work cutting a 5/8-in. thick aluminum part at New Way Packaging Machinery. At right, an employee displays the finished parts.

Machine shops of all sizes are discovering the benefits of cutting with ultrahigh-pressure water-jet technology. Material is removed by a supersonic erosion process and almost any material can be eroded, regardless of thermal properties or electrical conductivity. Since the introduction of abrasive waterjet technology by Flow International Corp., Kent, Wash., in the early 1980s, waterjet machining has evolved from a novelty to one of the fastest growing machine tool cutting technologies.

The reasons for this interest include waterjet's ability to replace costlier operations and reduce the need for secondary operations. It produces netshaped parts with no heat-affected zone, without inducing heat distortion or mechanical stresses. Waterjets cut with a narrow kerf and satin-smooth edge and can provide high material utilization because parts can be tightly nested. Also, waterjets can cut virtually any material including titanium, Inconel, brass, steel, aluminum, glass, stone, and composites. These benefits significantly increase productivity and reduce cost per part.

Waterjets can also cut material of any thickness with a minimum of fixturing and setup time. With PC-based controllers, such as Flow International's FlowMaster, an operator with very little skill or expertise can produce high-quality parts.

The versatility of waterjets expands a jobshop's capabilities beyond what is possible using only lasers, EDM, or milling processes. Although waterjets can cut materials up to 8 in. thick, most cutting done is between 1 /16 in. and 3.0 in. thick, with a finished part accuracy of ±0.003 to ±0.010 in.

Eliminating costly processes
The benefits of ultrahigh-pressure abrasive waterjet cutting are illustrated by the experience of New Way Packaging Machinery Inc., a Hanover, Pa., based shop manufacturing machines that label cans, bottles, and plastic jugs. New Way's customers range from large, multinational corporations to the smallest packaging operations.

In 1995, New Way was about to purchase several different machines — a laser, several computer-aided cut-off saws, and a CNC milling machine — to increase production of its proprietary parts. While researching these types of equipment, Flow International's waterjet cutting technology came to the attention of Ed Abendschein, president of New Way. Abendschein sent samples of the company's typical parts to Flow International's lab to see just how well the waterjets could cut. The waterjets performed beautifully. Within weeks, the company purchased a 2.5 axis waterjet machine with 7X intensifier pump and PASER 3 cutting system from Flow, eliminating the need to purchase five different machine tools, which saved hundreds of thousands of dollars.

In addition to these equipment cost savings, New Way was also able to reduce its inventory needs. Before waterjets, the company had to purchase 40 different sizes of varying thicknesses of angle-formed aluminum, stainless steel, or hot-rolled steel in 12 or 20-ft lengths. The material had to be cut to the proper length, the edges deburred, and each leg machined making sure holes or slots were cut in proper relation to each other. Now, New Way simply waterjet cuts each piece from flat stock and bends it.

Abendschein notes, "In addition, tolerances are better and part appearance is immeasurably better. As a result of our decision to purchase the waterjet machine, we have virtually eliminated two costly processes in our plant: machining angle stock and welding." By eliminating welding in its plant, New Way eliminated the need to hire two additional machinists and replaced manual machining with high-value, abrasive waterjet cutting.

Material versatility
"Waterjets are much more versatile than a laser," says Abendschein. "A laser does not cut shiny metals like aluminum and stainless steel. We manufacture some proprietary items in cold-rolled and stainless steel. With a laser we would have needed two separate manufacturing processes for each kind of material. Also, lasers give off poisonous gases when cutting Lexan. A waterjet cuts it without any ecological problems."

"The first major job we cut on the waterjet was a sponge rubber part, which the laser would have melted," continues Abendschein. "Until the waterjet arrived, we scheduled one man, one hour each day, to cut these parts. Once we had the waterjet, we bought four-foot wide rolls of sponge rubber, cut the rolls into 4 X 8-ft pieces, piled six pieces on the cutting surface, and cut with high-pressure water only. In one week — 40 man hours — we cut three years' worth of parts."