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Canadian Pump Maker Reaches New "Heights" A Cincron cell equipped with high-rise pallet storage, RGV system and a new Cincinnati Magnum 800 HMC is helping pump manufacturer Gorman-Rupp increase capacity and productivity without adding floor space or personnel
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ST. THOMAS, ONTARIO - A careful "balancing act" is how Jim Webster, manufacturing manager, Gorman-Rupp Canada Ltd., calls the transition from two stand-alone Cincinnati T-30 HMCs to a Cincron Automated Pallet Cell (APC). Initially consisting of a Cincinnati Magnum HMC-800 with dual-level pallet storage and Rail Guided Vehicle (RGV) pallet shuttle system, the cell will eventually grow to an APC with three HMC-800s.
Strategic Growth
The move to the APC is part of a larger strategic plan to add capacity and productivity—without adding cost in the form of expanded floor space, more operators, or time lost during the changeover.
Installed in 1996, the APC is the first Magnum-based cell to be fitted with Cincinnati's optional dual-level pallet storage system. Gorman-Rupp chose the high-rise approach to increase the amount of work that could be processed from the available manufacturing space. Long-range plans call for the T-30s and their twin 10-pallet automatic workchangers (AWCs) to be phased out, one at a time, as the company moves through the next stages of modernization and advanced technology acquisition. Immediate plans call for another Magnum 800 HMC with an additional dozen pallets, bringing the total to 30. At that time one of the T-30s will be retired. Later, a third Magnum will replace the last T-30.
"Actually", says Webster, "manufacturing is always a balancing act—if you're working effectively, utilizing your capacity and watching costs. The transition we're going through will allow us to further optimize our capacity and leverage technology. It's taking us to the next level in our plans. And with the first Magnum APC and dual-level pallet storage, we've got a lot of sophistication helping us balance things."
Pushing Technology
Gorman-Rupp pumps, positive displacement and centrifugal, are found in a wide range of applications, including waste water treatment plants; de-watering in heavy construction sites; fire fighting; coolant and fluid management in automotive and truck assembly plants; pulp and paper mills; aircraft refueling—to mention just a few. Fully assembled, the pumps can vary in weight from about 50 to 5000 lb (22.68 to 2268 kg).
To manufacture the heavy-duty pumps requires equally rugged and dependable machine tools. Pump materials are primarily cast and ductile iron, as well as some stainless steel, and the operations performed by the Cincinnati machines run the gamut: rough and finish milling, boring, drilling, tapping, thread milling, chamfering, reaming. Previously, these demands were met by running the T-30s an average of 80 hours a week, "lightly" tended during two shifts, plus another 7 to 7-1/2 hours a night untended. "That's really using, really pushing the technology," says Webster.
Already utilizing technology to the limit, it became apparent to Gorman-Rupp that something needed to be done when challenged to increase production from their existing facilities—more output from the same plant space. Forecasts and plans pointed to a need for increased capacity to maintain a competitive edge.
The dual-level APC provided a solution to a problem faced daily by a growing number of manufacturing managers: the need for increased capacity and productivity but without a complementary increase in costs—i.e. floor space and labor, or lost productive time. Gorman-Rupp now has 18 pallets on two levels in the APC. This takes about the same space as a T-30 with 10-pallet AWC, but provides nearly double the pallet capacity. In fact, the Magnum 800 HMC almost outworks the combined production of two T-30s, based on the same part quantities.
"Parasite" Removal
For example, metal-to-metal time for tool change on the older T-30 is about 15 seconds; on the Magnum it's 9 seconds, even changing the heaviest tools. "When you're running about 4000 conventional hours a year, plus another 1500-1600 hours untended, all those seconds add up," Webster says.
Additional parasitic time was eliminated via faster pallet changes. When Webster and his team evaluated parasitic time reductions for the Magnum compared to the T-30, they found an approximate savings of 13-15%. This primarily can be attributed to enhancements in higher torque and horsepower, feed and traverse rates, faster pallet change times, faster pallet indexing, and quicker tool changes. Bottom line, there's just less time lost—and more in-cut time gained.
A Closer Look
Webster indicates that they're currently processing 9 different parts, which he expects to climb rapidly to 15 to 20. "We've dedicated 12 pallets to two high-volume parts—those we run day after day, week after week," he says. "All the pallets are fixture-dedicated, and are constantly on the move, carrying multiple-fixtured parts weighing from as little as 20 lb (9 kg) or so, right up to 400 to 600 lb (181 to 272 kg)."
Typical APC operational sequence: The RGV shuttles pallets between the Magnum's pallet changer, off-line load/unload station, and the 18-pallet storage stands. The brain behind the system operation is Cincinnati's cell controller. It ensures that all the pallets, fixtures, tools and CNC machining programs necessary for continuous part processing are readily available. Working with the APC cell controller is a Programmable Logic Controller (PLC) which keeps track of each pallet and its location: loaded; on the pallet changer; being machined; at load/unload station; or in the dual-level pallet storage facility. The cell controller prioritizes work sequences by either time/date or by a priority numbered queuing system based on schedule needs. Ultimately, this allows for true just-in-time processing, including changing the workflow sequence—on the fly—due to demand changes. The controller "knows" what casting is on which fixture, on which specific pallet, stored in which parking space in the dual-level storage facility. And depending upon the method of priority, the cell controller can "schedule" when a casting will be machined. Once fixtured, the casting "rests" in its parking space until "called up."
For example, if a given part doesn't carry a particularly urgent priority, it may be scheduled for machining by date and time. On that date, the cell controller tells the PLC that it's time for the casting to enter production. The PLC then responds that the particular casting is fixtured on its pallet in space number such-and-such. The RGV is activated and retrieves the pallet, taking it to the Magnum.
Now in the world of JIT, it's entirely possible that between original part scheduling and the actual day of machining, demand priorities have changed, and a different part number now has a higher priority. The cell controller and the PLC, during the process of their "electronic handshake", would re-prioritize the part and place its pallet in a next-up status while the new, higher-priority parts are machined.
"The really impressive thing," Webster says, "is that while the cell controller manages everything relative to part processing—all the part programs and program storage, and special features like torque controlled machining, automatic tool recovery, probing, and tool wear monitoring—the communication between it and the PLC make the dual-level pallet storage, sequencing, and RGV retrieval system work. It's a complex electronic communications handshake that has to come off just right for JIT and untended operation, two strategies which are very much in our future—actually, in place now with the first Magnum."
Magnum Making It Work
The spindle is axially fixed and extends 16.1" (410 mm) from the face of the FEA-refined, nodular iron carrier housing. This tapered, double diameter, 8.5 and 11.8" (216 and 300 mm) snout design enhances Magnum's ability to reach tighter part features and into deeper cavities with short, rigid tools for optimum cutting rates and precision on Webster's primarily (95%) cast iron parts.
Webster indicates that this "power", speed, good tooling and fixtures pay off in significant dividends. "Some of our smaller parts might have a run time of 10 minutes," he says, "but we were able to improve fixturing to take advantage of the reduced indexing and save perhaps five minutes a part. At that rate, we pay for a fixture pretty quickly. Of course, this depends on the part mix and can't always be done. But on fairly large runs of common parts, this is a strategy that pays off nicely."
"We just put one of our larger parts on the Magnum," Webster continues. "We had the run time down to about 45 minutes on the T-30. Now we're running the part in 39 minutes on the Magnum. We've saved about six minutes per piece. Same fixturing, very same tooling; it's just a question of the Magnum being a lot quicker." For example, the Magnum offers a rapid traverse rate of 709 ipm (18 m/min) compared to 600 ipm (15 m/min) for the T-30.
AWC/ATC
The Magnum's standard automatic workchanger (AWC) doesn't let the spindle sit idle long. Idle, as Webster will tell you, doesn't add to the bottom line. The AWC keeps one pallet in buffer, immediately ready as soon as the machining cycle is complete.
The standard Magnum HMC-800 AWC includes two 31.5" (800 mm) square pallets, capable of switching workloads in seconds as heavy as 4847 lb (2200 kg) per pallet, 45.3" (1150 mm) tall by 51.2" (1300 mm) in diameter. Automatic pallet transfer on and off the machine Z-axis occurs at 1000 ipm (25.4 m/min). And once transfer is complete, a quick 180 degree spin on the carrousel brings a new pallet of parts into position for shuttle onto the Z-axis. During machining, the finished pallet is unloaded and reloaded with parts at the off-line station, ready for reassignment by the cell controller.
The 180-tool storage magazine on Gorman-Rupp's Magnum HMC-800 uses a simple double-fisted single arm design with twin tool grippers at each end to automatically change tools. The ATC accommodates tools up to 4" (102 mm) in diameter, 19.7" (500 mm) in length, and to 66 lb (30 kg). It will also handle 11.9" (300 mm) diameter tools—with adjacent pockets empty.
No Nonsense AcraSense
"The optional AcraSense software package," Webster says, "has been worth every penny." As part of the package, features like Torque Control Machining (TCM), Automatic Tool Recovery (ATR), and dynamic/static probing are "absolutely necessary" for aggressive cycle times and untended machining, as has been proven by the eight-year performance of the T-30s.
One of the ways the probing function is used is to check bores for concentricity. Then there's an option that tells the Magnum part presence or absence—if parts have only been fixtured on three corners of a fixture, the probe will tell the HMC to ignore the fourth corner. It's also used to probe the envelope of raw castings. This minimizes errors in terms of establishing depth of cut. If there's more material present than was thought, there's always the risk of stalling out the machine. Any time you're talking about stalling out milling cutters, you're talking about tearing up inserts, which gets very expensive, very fast.
TCM is helpful during boring/milling operations because it minimizes the load on the tool by either reducing or increasing the program feed. Webster adds that TCM plays a significant role in tool life and the attendant tooling costs. For instance, if it costs $1 a minute to run the machine, and if it costs $10 for an insert, and there are four corners to use, that's $2.50 per corner. If one gets 2-1/2 minutes on one corner, one's ahead of the game. If one gets five minutes out of the same corner, that's really doing well. If ten minutes, that's tremendous. If the average rough-milling time is five minutes, that's $5 in machine time. Now if one can do that with a single corner—well, the math is easy enough. The point is, that kind of tool life translates right to the bottom line.