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Copper Rotors Help Meet Unusual Requirements
Specialty Motor Manufacturer Finds Efficiency Is Good, but There's More to the Story However, efficiency isn’t always the single most important operating parameter, particularly in motors other than standard, 60-Hz, NEMA designs. Here, we’re talking about specialty motors, those designed to meet unique or particularly demanding requirements. Those requirements can include speeds in the tens of thousands of rpms at high power ratings, virtually silent operation, dimensional stability measured in angstroms and power densities (hp per pound or per volume) not attainable in even the finest conventional machines. This is edge-of-the-envelope electric motor design, and, not surprisingly, copper rotors are playing a major role. Many Options  While tweaking the rotor is only one of many options open to motor designers bent on achieving higher performance, one innovative manufacturer has found that die-cast copper rotors provide greater design flexibility as well as the ability to make cost-effective improvements in manufacturing. The company is Welco Technologies, a more than 110-year-old concern headquartered in Milford, Ohio, with manufacturing and R&D facilities in Maysville, Kentucky. Welco has gained an enviable reputation for providing unique motor solutions to customers in such diverse industries as glass and polymer fiber production, machine tooling, automotive (and other) test stands, medical imaging, commercial aircraft, and defense and aerospace. All Welco Technology motors are “special.” “We like to call what we do solutioneering, or solutions plus pioneering,” says Jim Kokenge, Welco’s director of business development. “People come to us because we have the experience and capability to design and manufacture motors for the most difficult applications, often when others have failed or when major motor suppliers won’t even try. We’ve created literally thousands of specially designed motors that you could never buy off the shelf. Although we do a lot of repeat business, our orders might involve as few as one motor or as ‘many’ as a dozen a month. These are not prototypes; they’re tailor-made machines made in limited quantities for very specific applications.” Forget About Aluminum So far, Welco has only used die-cast copper rotors in a handful of its motors. One reason: CDA’s production-scale die-casting technology is relatively new, and the rotors simply weren’t widely available in the past. Another factor is that the rotors aren’t always called for, as in Welco’s line of permanent magnet motors, whose rotors contain no copper whatsoever. There’s also a cost factor we’ll talk about later. But, according to Shailesh Kapadia, Welco’s vice president of technology and its principal motor designer, die-cast copper rotors offer important advantages, both in performance and manufacturability. This is particularly the case in the company’s AC induction motors, most of which are based on copper. MORE >> |
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