Technology waterfall: General Industry Coverage

As vice president of waterjet machine tool builder Flow International Corp., Chip Burnham frequently debunks common misconceptions about waterjets. One is that technological advancements have made the equipment more flexible and versatile over the years. “The waterjet has always been very flexible and versatile,” he countered. “Most consider it the most flexible and versatile machine tool available.”

This includes the waterjet’s ability to precisely cut nearly any material—from paper and food to brittle stone and the nastiest superalloys—in a host of environments, including short-run job shops, R&D labs, contract manufacturers and high-volume OEMs. A pure waterjet is suitable for cutting software materials, while an abrasive waterjet cuts hard materials, and most waterjet machines can perform either function.

Video presentation from Flow International Corp. offers overview of the waterjet machining process.

Burnham came to this realization when wanting to work with a pedestal robot for his senior project as an undergraduate in the mid-1980s at the University of Rhode Island. “I finagled my way into the lab that had the robot and, lo and behold, a waterjet was attached to it,” he said. “Shortly after that the robot became second to the waterjet for me.”

Flow had donated the waterjet to the university to promote “this whole intriguing technology,” Burnham said.

Take it Easy

What has changed is the ease of programming and operating an abrasive waterjet machine, according to Burnham. This enables someone with average rather than advanced skill to set up and cut a workpiece.

Nonetheless, to take advantage of a waterjet’s inherent versatility, high-end systems have advanced controls and built-in knowledge to take the guesswork out of waterjet programming and operation. “The programmer enters the pattern, material type, material thickness and desired quality level, and the machine knows how to select the right speeds and lead-ins and lead-outs without needing a series of test cuts,” Burnham said. “The easier the programming the better, since finding great programmers gets tougher and tougher.”

Process software plays a key role in transferring the knowledge a waterjet machine tool builder has acquired to end users—especially new ones, added Jeff Schibley, Midwest regional manager for St. Michael, Minn.-based Jet Edge Inc. “Regardless of whether you processed 1 “-thick steel in the past, the software instructs the machine that these are the parameters it will operate at and create this quality,” he said. “Now, the customer doesn’t have to have knowledge of abrasive waterjetting to run that machine.”

An EDGE X-5 5-axis waterjet system from Jet Edge can produce complex contours. Image courtesy Jet Edge.

Software that provides tutorials can also prove beneficial. Michael Ruppenthal, vice president North American Sales for OMAX Corp., Kent, Wash., gave the example of using a rotary axis on a waterjet machine to cut or create letters around a pipe. “Programming that job used to be difficult. You needed a highly educated programmer and machinist to figure out how to waterjet cut it,” he said. “Now all I need to do is tell the computer the diameter and thickness of the pipe and the size of the feature and the software does everything else.”

Technology Transfer

Along with making abrasive waterjet machines easier to run, builders frequently add features to entry-level equipment previously found only on higher-end offerings. “It’s what I call a ‘technology waterfall,’ which gradually happens in all machine tools,” Burnham said.

He noted Flow’s most affordable line, the Mach 2 series, has capabilities previously available only on the more-advanced Mach 3 and 4 series. For example, an entry-level machine, which starts at about $90,000, came with a 60,000-psi pump a few years ago and now can have a HyperJet 94,000-psi pump to cut faster, and instead of just having a conventional cutting head fixed perpendicular to the workpiece, the machine can now carry the company’s Dynamic Waterjet head.

OMAX has followed a similar path. Ruppenthal pointed out that the company carries two brands: OMAX and Maxiem, the latter being a standard entry-level line. “Maxiem has transitioned into an à la carte offering more so than the OMAX premium line, where you get the features even though you may not want each one for your application,” he said. “With Maxiem, you can put on almost all the same features that you can on an OMAX.”

This includes automatic abrasive feeding, which previously required manual delivery of abrasive to the cutting head, and automatic abrasive removal. Ruppenthal explained that abrasive, typically garnet, fills a catcher tank at a rate of approximately 1 lb. (0.45 kg) per minute, and the abrasive must be periodically removed via a shovel or sucker truck when a machine doesn’t have an automatic removal system. The system takes the solid material out of the tank and puts it in a disposal container, eliminating the need to shut down the machine and empty it. “More importantly, it saves somebody’s back from having to shovel that,” he said. “It’s the accessory we sell most often after the sale.”

The A-Jet from OMAX is a software-controlled, multiple-axis cutting head that expands the versatility of a waterjet machine by being able to produce a variety of features, such as beveled edges, angled sides and countersinks. Image courtesy OMAX.

Ruppenthal added that having the ability to raise and lower the water level and enable cutting underwater is another recent addition to the standard entry-level line. Cutting underwater increases workplace hygiene by keeping the shop cleaner and reducing worker fatigue, according to Ruppenthal. “The quieter the machine is, the less it affects the person standing around or near it all day long.”

In addition, a company that purchases either brand of machine can have 5-axis capability. Besides being able to remove taper, Ruppenthal noted that capability enables producing a part with complex contours, such as a turbine blade, and generating helpful features, such as a weld-prep bevel. “If you’re a job shop, it opens up business opportunities that you didn’t have before.”

Nonetheless, the vast majority of waterjet work is for flat-plate cutting or flat-plate bevel cutting rather than full 3D machining, including at part manufacturers with 5-axis waterjets, according to Burnham. Therefore, shops need a waterjet that can be easily programmed and used to execute bevels and K-bevels. “True 5-axis, 3D cutting requires your shop to have programmers and operators who can handle that type of work,” he said.

Not all builders introduce features found predominantly on higher-end machines to entry-level offerings. “When you’re building machines, you don’t add features and reduce the cost,” Jet Edge’s Schibley said. “You add features and increase the cost.”

Some shops are looking to bring the waterjet work in-house that they previously outsourced, but they don’t necessarily have 40 hours of work for machine. For this situation, Jet Edge offers the Boss-Cutter line. The machine has a 59 “×59 ” (1.51m) work envelope. “If the customer is used to buying 4 ‘×4 ‘ or 5 ‘×5 ‘ material, it will easily fit within the cutting tank of that work envelope,” Schibley said. He added that larger work envelopes are available for high-volume customers that prefer to buy larger full sheets at the most economical rate and avoid the saw cut and corresponding mark up from a metal service center.

Pressure Point

When helping a customer specify an abrasive waterjet machine, the first question is about the size of sheet to be cut, followed by the thickness of the material, the expected level of accuracy and whether a taper-eliminating cutting head is required, Ruppenthal said. “If you’re a fab shop, taper might be completely acceptable. Or if you’re going to put everything on a machining center after you cut it on the waterjet, some slight taper that the waterjet puts into the part might be OK.”

A Flow Mach 2c waterjet machine with a Dynamic Waterjet head cuts 7⁄8 “-thick carbon fiber. Image courtesy Flow International.

Ruppenthal added that a “dream” waterjet application involves the latter, particularly when processing difficult-to-machine workpieces, such as Inconel, Hastelloy and titanium, which might require 500 passes or more. After waterjet machining such a workpiece, say for 45 minutes, to near-net shape, the part will require significantly less time on a machining center.