Dedicated fixtures simplify pump housing machining

Author Cutting Tool Engineering
Published
March 01,2011 - 11:15am

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END USER: Weir Minerals North America, (608) 221-2261, www.weirminerals.com. CHALLENGE: Streamline workholding and machining of 12', 5,000-lb. cast iron pump housings. SOLUTION: Dedicated fixtures that cut setup and machining cycle time while improving operator safety. SOLUTION PROVIDER:  Advanced Machine & Engineering Co., (800) 225-4263, www.ame.com

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Weir Minerals North America, Madison, Wis., manufactures pumps, hydrocyclones, valves, screen machines and media, and rubber and wear-resistant linings for mining, oil field and industrial applications.

When the company needed machining of 108 "×108 " Class 40 cast iron slurry pump housings, it contacted Advanced Machine & Engineering Co., Rockford, Ill., to perform part of the required contract manufacturing.

AME_WierSlurry5x6.tif

Courtesy of AME

A dedicated fixture cut setup and cycle time while improving operator safety when milling 5,000-lb. cast iron pump housings at AME.

With each weighing more than 5,000 lbs. and consisting of a frame and cover section, the housing sets presented a workholding challenge for AME. They required milling, drilling and boring. In addition, they required an A and B load, which meant four setups were needed to produce a complete housing assembly. Rigidity was also key to avoid vibration and distortion from the enormous load and tooling masses involved. AME was machining two to three housing sets per week.

Although AME was delivering pump housing sets to specification and on time using nondedicated fixturing, part setup took too long, according to Steve Schubert, AME’s vice president of operations. Changeovers took up to 8 hours. Locating and clamping the housings was quite tedious, and the methods used raised several safety concerns in materials handling, strapping and clamp positioning.

In addition, clamping forces were less than optimal, which increased machining cycle time and reduced tool life.

“The challenge was to design a fixture that was within the weight limitations of our machine table without compromising the structural integrity and rigidity of the fixture itself,” Schubert said. “We also needed a design that would allow for quick change of the workpiece, as we did not have a two-pallet machine. Finally, but most important of all, we were extremely concerned about safety. We needed a fixture that would allow safe usage for the machine tool operator and be secure enough to not allow one of these massive parts to fall off of the table.”

AME’s solution came from its product line. The company developed a single, dedicated AMROK fixture measuring 120 " wide × 110 " high, with adjustable jacks to support the pump sections during machining on a horizontal mill.

The switch to a dedicated fixture resulted in multiple benefits. Because the fixture held both A and B loads for each workpiece, setup times were reduced to less than 50 percent of the previous method. The dedicated fixture also improved locating and clamping, resulting in a 45 percent reduction in machining cycle time per pump set, improved part quality and surface finish, and enhanced operator safety by using standardized lifting, locating and clamping methods.

AME shared the savings with its customer, and Weir Mineral was so pleased that it transferred work from other contract manufacturers and awarded the entire project to AME.

Related Glossary Terms

  • boring

    boring

    Enlarging a hole that already has been drilled or cored. Generally, it is an operation of truing the previously drilled hole with a single-point, lathe-type tool. Boring is essentially internal turning, in that usually a single-point cutting tool forms the internal shape. Some tools are available with two cutting edges to balance cutting forces.

  • fixture

    fixture

    Device, often made in-house, that holds a specific workpiece. See jig; modular fixturing.

  • gang cutting ( milling)

    gang cutting ( milling)

    Machining with several cutters mounted on a single arbor, generally for simultaneous cutting.

  • materials handling

    materials handling

    Methods, equipment and systems for conveying materials to various machines and processing areas and for transferring finished parts to assembly, packaging and shipping areas.

  • milling

    milling

    Machining operation in which metal or other material is removed by applying power to a rotating cutter. In vertical milling, the cutting tool is mounted vertically on the spindle. In horizontal milling, the cutting tool is mounted horizontally, either directly on the spindle or on an arbor. Horizontal milling is further broken down into conventional milling, where the cutter rotates opposite the direction of feed, or “up” into the workpiece; and climb milling, where the cutter rotates in the direction of feed, or “down” into the workpiece. Milling operations include plane or surface milling, endmilling, facemilling, angle milling, form milling and profiling.

  • milling machine ( mill)

    milling machine ( mill)

    Runs endmills and arbor-mounted milling cutters. Features include a head with a spindle that drives the cutters; a column, knee and table that provide motion in the three Cartesian axes; and a base that supports the components and houses the cutting-fluid pump and reservoir. The work is mounted on the table and fed into the rotating cutter or endmill to accomplish the milling steps; vertical milling machines also feed endmills into the work by means of a spindle-mounted quill. Models range from small manual machines to big bed-type and duplex mills. All take one of three basic forms: vertical, horizontal or convertible horizontal/vertical. Vertical machines may be knee-type (the table is mounted on a knee that can be elevated) or bed-type (the table is securely supported and only moves horizontally). In general, horizontal machines are bigger and more powerful, while vertical machines are lighter but more versatile and easier to set up and operate.