Page 30 - MetalForming May 2017

Waterjet Warriors
and cost. Typically, though, parts that will be machined after cutting can be plasma-cut. But if the profile is the fin- ished product, then we opt for laser or waterjet.
“Any holes that will not be machined or reamed,” Herff continues, “are cut on the waterjets as well—such as fin- ished holes for bolts or through which round bar must pass during assembly. We often ask the customer for the com- plete assembly drawings when evalu- ating process-processing strategies, rather than just the part drawing. With the complete assembly drawings, we can evaluate the application and rec- ommend the optimum cutting process.”
As an example, Fagan describes a recent project from a customer that typically requests plasma cutting. “However, in this case,” he says, “when we looked at the assembly drawings, we noted that the parts required a very smooth surface finish. We talked them into waterjet cutting to eliminate any post-machining operations.”
A high-profile job completed recent- ly by the service center had it cutting 3⁄4-in. stainless plate for Omaha, NE, fabricator Puritan Manufacturing, con- tracted to build a massive 55,000-lb. sculpture for the University of Nebras- ka’s sports arena. The sculpture, describes Herff, combined two-side- polished plate with holes cut in some sections through which polished tubes were to be inserted.
“Here I worked closely with the cus- tomer to determine the optimum clear- ance between the tubes and the hole diameter to prevent damaging the sur- faces during assembly,” he says. “Water- jet cutting the plates allowed us to meet tight tolerances and achieve the desired surface finish.”
True Workhorses
The trio of waterjet machines are true workhorses. The shop typically runs 50-mesh garnet, suitable for near- ly all of its stainless-steel plate-cutting work. For particularly thin-gauge sheet- metal and more precise cuts, it’s equipped one of the three machines
The workhorse waterjet machines make thousands of inches of cuts in stainless-steel plate as thick as 6 in. week in and week out. “We’ve outfitted all of them to be powerful and large—we don’t ever want to be limited in what we can process,” says Pete Fagan, Metals & Services Co. general manager. “We specifically looked for powerful pumps to drive the three cutting heads (on each machine), without sacrificing cutting speed and quality.” The pumps of choice are Hypertherm HyPrecision 150D models, 60,000-psi dual-intensifier pumps equipped with 150-hp motors and featuring several notable con- trol functions designed to optimize ease of use.
28 MetalForming/May 2017
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with dual garnet hoppers.
“We load that second hopper with
120-mesh garnet,” says Herff, “for fast changeovers. We also use that fine gar- net to cut aluminum.”
“We run the machines 20 hr./day over three shifts,” adds Fagan. “We’ve outfitted all of them to be powerful and large—we don’t ever want to be limited in what we can process. We specifically looked for powerful pumps to drive the three cutting heads (on each machine), without sacrificing cut- ting speed and quality.”
The pumps of choice are Hyper- therm HyPrecision 150D models, 60,000-psi dual-intensifier pumps rated for a maximum orifice diameter of 0.025 in. They’re equipped with 150-hp motors and feature several notable control functions designed to optimize ease of use. These include what Hyper- therm calls advanced intensifier mon- itoring, for early detection of leakage; an enhanced maintenance interface along with a web-based interface for remote access to system and mainte- nance performance; and control of inten- sifier settings during pump operation.
“Maintenance of
These Cutting Machines
...since they’re so critical to our suc- cess, remains a focus for the shop,” says Herff. “The biggest challenge is keeping them clean, as over time garnet can build up in the tables. We’ve spent the last several month researching options for keeping the machines clean, to avoid having to drain the tables and shovel the garnet out.”
What Herff and the team settled on, after its due diligence, was an Extractor garnet-removal system. “One hose, moved around the table, even during cutting, by an operator pulls water and garnet out of the machine, while another hose recycles the water back— stirring the water and garnet around so that there is no sediment left in the machine,” Herff says. “In a couple of hours, the Extractor is full—we just use a forklift to raise it up over a dump- ster to empty it; no special disposal requirements.
“The unit is phenomenal,” he con- tinues—a real game changer to put a charge into our waterjet-machine OEE.” MF