An impromptu process switch and double-duty tooling helped Canyon Hydro machine hydropower runners faster and deliver them sooner.
Sometimes a fallback process can put you far enough ahead to warrant making it your new standard.
Canyon Hydro makes hydropower runners in diameters from 18 inches to more than 11 feet across in its free standing CNC machining center in Sumas, WA. Runners like the one being installed here can involve 500 hours of long-reach contour milling.
Canyon Hydro, Sumas, WA, recently did exactly that after deciding to switch to billets from castings as machining feedstock for their smaller hydropower runners. What made the difference were a last minute processing switch and a big new Ingersoll Quad F multipurpose mill that dramatically sped up the roughing operations. About 4500 lb of chips came off in one third the time as with conventional face mills -- and far faster than by the originally planned turning operation.
Runners, the heart of all hydropower machinery, are very sophisticated water wheels made of stainless steel. They may measure anywhere from 18 inches to more than 11 feet across, weigh up to fifteen tons and spin at up to 1000 RPM to generate electric power. Smaller runners are machined from solid; larger ones are fabrications. For hydrodynamic efficiency and dynamic balance in service, all finished runners must be accurate to 0.010" with a 32µ finish.
Most of the contour roughing and finishing is done with this large but standard Ingersoll Form Master indexable ball mill. The same tool handles roughing and finishing; only the machining parameters are changed.
The largest supplier of hydropower machinery west of the Mississippi, Canyon Hydro produces the runners in a state-of-the-art plant. It normally operates 16/6; in peak times it goes to 24/5. "The common denominator of our work is 4-6 axis long-reach contoured cavity machining on stainless steel," says manufacturing manager Loren Sweitzer.
Planning, Then Improvising
Actually, Canyon made two significant processing changes, one planned and the other not. For strategic reasons, the company plans to convert from castings to billets as feedstock for runners up to 70 inches diameter that are machined in one piece.
"Billets carry a much shorter delivery lead time than castings, are much more consistent dimensionally and contain no sand inclusions that can suddenly rupture a cutting edge," explains Sweitzer. "Total floor to floor time with a billet is about the same as with a casting, even though more stock must be removed. With billets, we should be able to simply fixture the piece, push START and stand back."
Rough milling of hydropower runners goes much faster with Ingersoll Hi Quad F cutter. The tool combines high feed geometry with capacity for higher depths of cut to get the most out of higher power machines with limited feed rates.
The first billet, for a 52 inch runner with a rush delivery requirement, hit the floor in February, 2014, eleven weeks sooner than castings could be delivered. The big disc measured 52" dia by 12 3/4" thick and weighed 9000 lb. About 4000 lb of stock needed to come off in initial roughing operations, essentially a four-axis job.
Originally shop manager Ken Neal planned to rough the symmetrical portions by turning and then to transfer the piece to a five axis mill for the rest. Trouble was, the lathe able to take such heavy workpieces was tied up for weeks for other work, yet the customer needed the runner sooner.
Smart Plan B
So instead, Ken Neal and lead man Jake Rawls moved the job on a six-axis Kuraki KBT 15BDX horizontal mill with a 44,000 lb turntable tooled with Ingersoll 3 inch Power Feed mills and 2 inch Form Master ball mills on 15 inch extensions. With their high feed geometry, both tools have become Canyon Hydro's mainstay for machining their larger fabricated runners, which are typically run on very large high-feed CNCs. However, the Kuraki emphasizes power and rigidity over table feed; it has a 35 HP spindle but a maximum feed rate of only 140 IPM. It's not a high-feed machine.
Canyon Hydro reports removal rates up to 50 cu in/min in stainless steel, with edge life averaging 7 hr in the cut and ranging from 2 to 45 hr depending on the parameters.
Using All the Power
Quickly recognizing the spindle power available and the tonnage of metal to be hogged out, Jake Rawls asked Ingersoll's Chris Murray for a 6-inch version of the Power Feed mill that had become a Canyon Hydro mainstay.
Instead, Chris recommended the new 6-inch Hi Quad F mill, reasoning that it would work better in such a high-torque, limited-feed situation. "Although it's a high feed tool, the Hi Quad F has the geometry to take much deeper cuts where the feed rate is limited," Murray explained. "Moreover, its free cutting geometry and 12 degree lead angle reduce lateral cutting forces, for more stability in long reach milling."
Four Step Roughing Sequence
In the first 24 hours of operation, a six inch and a four inch Hi Quad F face mill, each running on 5 inch extensions, combined sequentially to remove about 3500 lb of stock in continuous contact service. The former ran at 312 SFM, 120 IPM, 0.100" DOC to peel off 50 cu in/min with a predictable 45 minute edge life in the cut. The latter ran at 442/70/0.100 with edges lasting 90 minutes in the cut. Edges were changed solely because of wear and surface finish, never for rupture.
Canyon Hydro's billet experiment sped up deliveries by two months.
The 2 inch Power Feed, a very strong high feed face mill, followed to handle some of the asymmetrical portions and the interrupted cuts created in the first operation.
Finally the 1.5 inch Form Master, an advanced button mill, went in to complete deeper portions of the cavity -- and some undercuts -- on 15 inch extensions. These are the areas most likely to create chatter. Nevertheless, Canyon Hydro ran it at higher than recommended parameters with no chatter whatsoever. "The higher feed rates actually helped stabilize the tool," said Rawls.
The Form Master button cutter works like a standard contour mill for most of the pass, then like a T-slotter for the undercut portions. To defeat harmonic vibration, it features asymmetric flutes and serrated round inserts in a "timed" array. Each insert is turned "five minutes" from the other, so each edge engages a different area of the cut and the whole toolpath is covered progressively with every full cutter revolution. "Essentially it's a progressive button mill with chipbreaker inserts," says Murray.
Newcomer, Close Up
Although Canyon has relied largely on Ingersoll tooling since opening its doors at the lights-out plant in 2009, the Hi Quad F is a newcomer. Key to the cutter's effectiveness is the combination of high feed and deep-cut geometry in the same tool, according to Murray. With 19 mm inserts it can handle depths of cut up to 0.118 inch. It also accommodates seven different styles of insert to address a wide variety of machining conditions and materials that Canyon Hydro encounters.
Inspection of Canyon Hydro runner during the polishing phase.
"I can see using the Quad F on our larger runners and runner buckets as well," says Neal. The big ones can involve months of continuous five-axis chipmaking on 28-inch extensions.
In summary, the billet experiment, feedstock, and processing changes sped up deliveries by two months without raising machining costs. "The chipmaking ran very fast and free of interruptions so typical of machining castings, with inserts lasting 7 hr in the cut on average," Rawls added. "With the tooling package we used, it worked out better than expected, and far better than by starting with a turning operation."
Final inspection of a completed runner before packing for shipment.
As a result, Canyon Hydro is working toward standardizing on billets as feedstock for runners up to 70 inches milling them with the same tooling package. "We're feeling our way here," says Sweitzer. "But success on this 52 inch runner certainly bodes well."
"A lot of our work is one-off jobs on short lead times, so we don't have time to run a full tool evaluation whenever a new need arises," Neal added. "In this case, we had a job on the floor that was running too slow, and thought we simply needed a bigger version of a proven tool. The better idea came from Chris Murray right on the spot. We rely on such vendors, because we don't have time to research all tooling options when a new job hits the floor. We look for guys who solve problems quickly rather than selling hardware."
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