Clean and Precise--Waterjet Meets Sanitary Stainless Standards

By: Brad Kuvin

Sunday, May 1, 2016

Wolfe Industrial’s new waterjet-cutting machine, the company’s second, features a 6.5 by 13-ft. worktable and 60,000-psi pump. It’s a workhorse for the company, cutting primarily sanitary stainless-steel sheet and plate for conveyors and other handling equipment used in food-processing plants.
Abrasive-waterjet cutting leaves a tapered edge, and the faster you cut the greater the V-shaped taper. Traditionally, to compensate fabricators either have to slow down or make adjustments in weld-joint design or weld-prep steps, assuming that cut parts are to be welded.

Those concessions simply are unacceptable in today’s highly competitive job-shop sheetmetal-fabrication environment. For awhile customers used to look just for suppliers who will jump through hoops for them, “now customers want us to jump through hoops of fire,” says Derek Wolfe, operations manager at Wolfe Industrial, a metal fabricator and installer based in LaVergne (Nashville), TN. “Meeting and exceeding customer expectations gives us little to no room for waste in our processes.”

Waterjet Machines Answer the Call

Wolfe’s perspective played out last year when the company found itself in the midst of rapid expansion, primarily due to growth in the food-processing arena. To meet increased demand for fabricated-sheetmetal products, the company had to find a sheet- and plate-cutting machine that would allow cut parts to move directly (or as quickly as possible) to downstream operations. Enter a new Flow Mach 3 machine (Model 4020b, with 6.5 by 13-ft. worktable and 60-ksi pump), brought in late in 2015 to work aside the company’s first waterjet-cutting machine. That’s also a Flow model, which has been a mainstay in the company’s 54,000-sq.-ft. shop since 2005.

“While we used to focus primarily on the automotive industry,” shares Wolfe, “80 percent of our work now goes to the food-manufacturing market. The majority of that requires fabrication of stainless steel—conveying equipment, chutes, hoppers and the like. In the last year we’ve grown by nearly 40 percent, and so did our need to cut sanitary stainless-steel sheetmetal and plate. Plasma cutting (the firm operates an 8 by 10-ft. plasma table) might have sufficed for cutting mild-steel work for automotive customers, but not for clean-cutting stainless steel.”

Wolfe’s expertise in stainless-steel fabrication includes gas-tungsten-arc welding. Here a welder works on waterjet-cut Type 304 stainless-steel ductwork (14-gauge sheet) and fittings (3⁄8-in. plate).
In addition to fabricating and installing processing equipment, Wolfe also fabricates a range of air-handling equipment, including ductwork and piping. It operates a glass-bead-blast facility as well as an oversized paint booth.

An End to Edge Taper

Wolfe’s new waterjet machine not only produces clean edges, it features Flow’s Dynamic Waterjet technology that does away with edge-taper concerns. The technology is based on mathematical modeling to predict taper angle, then compensating by adding the required wrist articulation. This action is managed by Flow’s FlowMaster Windows-based control system, based on user-input process parameters such as material type and thickness, cutting speed and desired angle quality. The cutting process, with edge-taper compensation, then occurs without intervention by a Wolfe programmer or operator. It pushes the taper to the scrap side of the workpiece to ensure a precise part-edge profile—four to six times more precise than a conventional waterjet, say Flow officials, with a much higher cutting speed.

“That’s critical to ensuring that we continue to meet lead-time requirements,” says Wolfe, “which of course have been tightening.”

While nearly all of the projects undertaken at Wolfe Industrial are custom, here’s a repeat job it performs for a metal-powder atomizer. The three-piece assembly includes a copper-alloy furnace-nozzle insert fabricated from waterjet-cut 11-gauge sheet.
Also helping to optimize throughput is the recent adoption of common-line cutting, as explained by shop foreman Ritchie Alexander. “That lets us minimize cutting time, while also improving sheet utilization. And, with the increase in throughput, we’ve added other pieces of equipment downstream of the waterjet machines—a new CNC press brake, new four-roll plate bender and several new welding stations.”

Clean Cuts Eschew the Need for Sanding

Wolfe employs 25 in the shop and another 80 or so in the field working on installation and maintenance projects at several sites at any one time. It numbers 120 active customers and processes material from 26 gauge to 1.25 in. thick. As much as 80 percent of the material it cuts moves on to be formed and/or welded, and waterjet-cut work in particular rarely if ever requires any additional cleanup.

Which Abrasive is Right for the Job?

Wolfe feeds its waterjet-cutting machines a general-purpose alluvial-garnet abrasive (Barton 80 HPA, at about 1 lb./min.), which “provides good edge quality and solid cutting performance,” says Barton literature. Also available to fabricators are more aggressive garnets for higher-speed applications and a more fine garnet that optimizes precision and generates the smallest possible kerf.

How do you know which garnet abrasive best-fits the jobs at hand? Well, seemingly like every other sheetmetal-job-shop process, there’s an app for that. Check out the Barton Abrasive Value Calculator, available for iPhone and iPad, which generates a cost comparison of available garnets based on a bevy of parameters. These include cost, cutting speed and hourly shop rate.

“Before we added the second waterjet machine,” shares Alexander, “we often were forced, due to capacity constraints, to cut some of the stainless steel on our plasma-cutting machine and then drill any of the holes that were required. The secondary hole-drilling process diminished throughput, not to mention the need to sand off any edge discoloration from plasma cutting. That’s all become a thing of the past with the new waterjet machine.”

We saw several examples of the quality of the work coming off the new waterjet machine. Included were parts being cut from Type 304 stainless-steel sheets (5 by 10 ft.) for fabricating chutes and ductwork for a General Mills food-processing plant; and copper inserts for furnace nozzles, fabricated for a company that gas-atomizes metal powder.

“When we were automotive-focused,” says Wolfe, “it often was difficult to differentiate ourselves from the several other shops around that can do that kind of work. Now, thanks in part to becoming experts in stainless-steel fabrication, we can make a name for ourselves and separate from the pack.” MF


See also: Flow International Corp.

Related Enterprise Zones: Fabrication

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