Large Lathe Succeeds Through Effectiveness At Machining Smaller Parts, Too

This maker of power transmission components wanted to replace its 1920s-era big lathe, but there was not enough large-part work to justify the new machine on this basis alone.

Case Study From: 7/23/2007 Modern Machine Shop

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Largest shafts

The largest shafts that the company machines and assembles are 20-foot-long, 1,000-mm drive shafts. The most common size it produces are 60-inch-long shafts featuring a 285-mm flange. The new lathe is versatile enough to efficiently handle both the large shafts and smaller jobs.

Machine Service, Inc. has been designing and manufacturing power transmission equipment since 1948, specializing in precision industrial drive train components. Based in a 78,000-square foot facility in Green Bay, Wisconsin, MSI has 100 employees who provide customers worldwide with capabilities for cleaning, milling, turning, drilling, boring, welding, straightening and balancing precision components. Products include transmissions, differentials, clutches, U-joint and driveshaft components, 4x4 axles and transfer cases, as well as universal assemblies.

In most cases, the company uses its array of machine tools to produce “normal” sized components for marine, construction and industrial drive trains. However, some components are much bigger than this. Industrial operations such as mills and mines that use large pieces of production equipment require driveline components in dimensions beyond the scope of the average machine tool. Drive shafts, for instance, can be as long as 20 feet. These larger pieces still require precision machining.

Obviously, the company needed a big lathe to produce such oversized shafts. It had been getting by with a large lathe made by American Lathe Company.

“It was so old—made in the 1920s, I would guess—that it originally ran off line shafts, but had been retrofitted at a later date with an electric motor,” says Bill Fowles, vice president of Machine Service. “At the time that we bought it, our only need was for a machine that could face off very long tubes and chamfer the outside diameter for welding. This old-timer measured 312 inches between centers, with a 40-inch swing over the ways, so it was adequate for the job—at the time.”

As orders for larger shafts began to increase and jobs began to require more complex machine work, the older lathe became increasingly inadequate to the demands Machine Service was facing.

“We were having to do more than just face off and chamfer tubes,” says Mr. Fowles. “We needed to perform accurate machining, like modifying some of the drive shaft components and machining end fittings.”

It was time to look for a new large-size lathe. Size capacity was obviously a primary concern in making a choice, but so was the equipment’s capacity to return the company’s investment. The largest shafts the company machines and assembles are 20-foot-long, 1,000 mm drive shafts. The most common size it machines are 60-inch-long shafts featuring a 285-mm flange. The new lathe would have to both comfortably handle the large shafts and take on the smaller jobs as well.

“It would have to be adaptable to ensure a reasonable ROI,” Mr. Fowles says. The company decided on the Knuth Machine Tool USA DL/Heavy lathe Model DL500/8000. Measuring more than 36 feet long with a distance between centers of 26 feet 3 inches and a linear travel distance of 26 feet 1 inch, the machine has a maximum turning diameter of 39.4 inches. Its main motor, rated at 30 hp, can operate at speeds ranging from 3 to 315 rpm. Combined with the high precision, that top speed has made the machine effective for a range of the company’s parts, even those that don’t come close to filling its size capacity.

“Like any machine, when it’s on the floor, you keep it busy however you can,” Mr. Fowles says. “We bought this big lathe primarily because we needed it for our large drive shafts, but it is adaptable to smaller jobs and to doing both coarse and fine machining. That makes it a practical tool on our floor, and that’s what lets it pay for itself.”

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