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  • Spinning in Moscow
    Posted by Michael Mecham 7:20 PM on Mar 06, 2012

    Anderson Leveille grew up in Stowe, Vt., and got his first high-school job in the circa-1820 sawmill his dad owned. There were no blueprints or tolerance gauges, so maintaining the wooden teeth on the mill’s bevel gears, which were lubricated with sheep tallow, taught Leveille the value of creative engineering.

    Fast forward a few years, past his roofing jobs in St. Thomas, his service as first mate and chief engineer on the 73-ft. Matador 2 that won the 1993 Fastnet Race, and his advisory role in the 1995 America’s Cup trials for the women-crewed Mighty Mary that came within seconds of winning, and we find Leveille back in Vermont, starting Moscow Mills.

    Credit: VIBRATION SOLUTIONS NORTH

    Located near Stowe, Moscow Mills specializes in R&D, engineering and manufacturing of high-precision components for prototype and short-run markets. Wooden gears have given way to 5- and 7-axis computer numerical control equipment. The company is small, just 15 employees working in a 12,000-sq.-ft. plant, but its components have been used for a variety of purposes, from fusion research to spacecraft instruments. In partnership with Boston Engineering, Moscow Mills Manufacturing created a stainless-steel tissue-slicing device for university researchers. Called a Goniometer, it was designed to slice a 1-mm cube of brain tissue into 50,000 20 nanometer-thick slices with tolerances of ± 2 nm. The slicing was done with a diamond blade just 12 atoms thick at the tip.

    “I wouldn’t say we’re cutting edge,” says Leveille. “We’re bleeding edge. We’re constantly being asked to do impossible things. That’s where we specialize.”

    In 2010, Leveille brought a veteran of balancing and vibration mitigation for aerospace, George Allen, on board and started Vibration Solutions North as a subsidiary. VSN’s core product, Kin-Dex, uses kinematic mounting to index and locate parts for precision equipment on fixtures or tooling—such as this low-pressure turbine air-bearing lock (shown)—so their balance can be demonstrated to high levels of accuracy and repeatability. “The better it repeats, the better the results,” says Leveille.

    VSN’s focus is on making tooling that interfaces a component or assembly to a balancing machine. Aviation’s gas turbine engines are a natural market, and the company pursues work with original equipment manufacturers and engine maintenance, repair and overhaul centers.

    “Efficiency gains are the top issue,” Leveille says. “There are big opportunities for MROs and OEMs to improve their processes with our type of tooling, to get better results in less time.”

    Better results in less time is certainly on the mind of Ben Morrison, the lead balancing technician at engine repair specialist StandardAero. Manufacturers often do not update manuals, so StandardAero’s technicians are on their own dealing with the intricacies of heating and cooling cycles in component balancing, he says. Should a part be seated slightly differently from one test to another, different values will be delivered. In the early days of overhauling CFM56s, it took Standard­Aero’s technicians three weeks just to balance a high-pressure combustor, he says. Experienced technicians typically take a full week to balance a complete engine. Shortening shop-visit times, which can run 60-90 days, is a competitive advantage, so StandardAero has Kin-Dex under evaluation, Morrison says.

    VSN’s tooling is also used by other manufacturers. CEMB has been building balancing machines for aviation in Modena, Italy, for 50 years, selling to Rolls-Royce, Pratt & Whitney, Snecma, Agusta­Westland and others. “In a lot of applications, the balance machine itself is not enough, you need to support the rotor that is needed to achieve the balance,” says Commercial Director Marco Biffi. For that support, CEMB uses VSN tools on horizontal balancing machines for compressors and turbines. “They are really expert,” Biffi says of VSN’s tool-making. “George [Allen] is particularly expert in balancing programs.”

    Unbalance is always defined in terms of the mass at a radius, Leveille explains. The larger a wheel, the smaller the allowable eccentricity. A 500-lb. wheel has a balancing tolerance of just 0.00025 in., but a 50-lb. wheel’s tolerance is 0.0025 in.

    As engine makers introduce new designs for greater efficiency—many with higher bypass ratios, some with fans rotating at different speeds than the core—the tolerance levels for unbalanced engines will grow smaller, says Leveille. Simulator tools may have merit for evaluating systems or diagnosing assemblies, but they are no substitute for rotor-specific balancing tools.

    Tags: AWCOL

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