Case History #2 Fixturing Large Workpieces Efficiently

CASE HISTORY

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COMPANY:
Masoneilan
Avon, MA

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PROBLEM:
Fixturing large workpieces efficiently.

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SOLUTION:
Modular chain fixtures.

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Masoneilan, produces control valves and instrumentation for various industries, including power plants, nuclear, and oil and gas. The valves regulate various types of flow.

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For a valve assembly, the body alone can weigh up to 3,000 lbs. The components that are assembled to the body, such as a “bonnet,” can weigh 1,000 lbs. Then, there are the internal flow-regulating components, which can be the “size of a basketball,” said Lou Luciani, lead champion for Masoneilan, Avon, MA .

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The components are made out of carbon steel, stainless steel or other alloys such as Monel and Iconel. The component sizes vary. A 16″ valve, for example, requires the area of a 50″ cube.

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Masoneilan purchased a CNC vertical turret lathe for turning and a horizontal machining center for milling and drilling. Runs range from one to four pieces.

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Work holding was a problem because of the large size and varied contours of the components. In the past, Masoneilan jury-rigged the work holding. “We just built blocks around the work piece,” said Luciani. “This approach was time-consuming and inefficient. The setup time idled the machine and required a lot of operator intervention.”

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Masoneilan approached Royal Machine, Berlin, Conn., for suggestions because “they have a very good reputation,” Luciani said. “We have used their products on other machines and the performance is reliable. We felt we should stay with them because of the interchangeability of the fixture components.”  Royal’s engineers recommended modular chain fixtures to hold the large workpieces. These fixtures reduce the number of dedicated fixtures needed for a given family of parts. They expand and contract along the X-, Y- and Z-axes to suit different-size workpieces by rearranging the basic location of clamping and locating components.

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The new method on the HMC requires zero online setup time. “While the machine is making part A on pallet 1, we are setting up part B on pallet 2–there is zero setup time,” said Luciani.

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“Modular chain fixtures help produce high-quality work pieces. It is more predictable and quickens cycle times. With the old method on the HMC, the cycle time typically ranged from 3 to 4 hours with half of that being spent on setup,” said Luciani.

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With the new method on the HMC, the time is less than an hour. The chains play an important role in this fixturing concept. After a work piece is positioned in the fixture, the chains go over the prepared or irregular work piece surfaces and secure the components so they can be machined. The chains are very flexible,” said Luciani. “They match the contour of the work piece they are holding. Like most companies today, we are facing some very competitive times. A lean process gives us an edge by improving quality, cost and delivery,” he concluded.”

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