Challenges in Wind Turbine Components

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Challenges in Wind Turbine Components

• Charles D. Schultz, PE
• Beyta Gear Service
• Winfield, Illinois

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What is going on in Wind Energy?
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Activity on a national scale
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Progress has been made but much remains to be
done!
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It is all about jobs!
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Domestic Content Progress
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US Wind Resource Map

• US is the Saudi Arabia of wind
• Transmission of power from central plains to
  coasts is a problem
• Even states that arent colorful have wind
  potential

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Examples of Components

• Blade Hubs are huge castings up to 15,000
  pounds
• Gearbox Assemblies weigh up to 60,000 pounds and
  are getting larger
• Chassis are big fabrications or castings up to
  40,000 pounds and getting larger

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Towers Blades

• Transport issues, 50 meter lengths 40 ton
  weights
• High cost items
• Potential for big improvements
• Big incentive to make locally

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Big Market, Long Term Potential
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Where are the problems?
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Quality is a given

• Due to high cost of warranty work all parts have
  strict quality specifications
• Tolerances test equipment capabilities
• Documentation requirements similar to aircraft
  industry
• Little acceptance of non-conformances
• Metallurgical cleanliness at aircraft levels
• Expect to cut up lots of samples for
  metallurgical checks

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Consistency is Mandatory

• Expect customers to dictate suppliers, methods,
  and even tooling
• Customers will have quality observers in your
  facility
• Once a method is approved changes are difficult
  to make
• Rework especially in thermal processing- is
  subject to extreme scrutiny

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Big portion of value is in the Nacelle
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Large, precision gearboxes required

• Aerospace precision in a mining machine sized
  package
• Quality levels far in excess of industrial
  equipment
• Huge warranty and maintenance costs

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Other Geared Products
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Planetary designs predominate
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Typical Gearbox Parts
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Typical Pinion

• Not dissimilar to industrial gearing
• Large cross sections challenge heat treat
  response
• 18CrNiMo7-6 typical material
• Current weights up to 2500 pounds and getting
  bigger

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Typical Sun Pinion

• Large thru hole helps heat treat response
• 18CrNiMo7-6 typical material
• Heat treat distortion common
• Current weights up to 2000 pounds and getting
  bigger

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Typical Gear

• Not dissimilar to industrial gears
• Large cross sections challenge heat treat
  response
• 18CrNiMo7-6 typical material
• Super finishing issues
• Current weights to 10,000 pounds and getting
  bigger

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Typical Splined Hub

• Typically thru hardened but some nitrided or
  induction hardened
• Length up to 30 is a shaping challenge
• 42CrMo4 typical material
• Current weights up to 2500 pounds and getting
  bigger

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Typical Ring Gear

• As large as 3 meters
• Many thru hardened
• Nitriding popular
• Induction hardening is also used
• Carburizing possible but problematic
• Shot peening and super finishing issues

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Typical Planet

• Lots of planets needed 3, 4, or 5 per stage
• Precision size matching within sets
• 18CrNiMo7-6 typical material
• Current weights up to 2200 pounds and getting
  larger

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Serial Production not job shop!

• 7,000 turbines per year 27 per day
• 10,000,000 cars per year 38,462 per day
• Typical large industrial gear shop does less than
  5 gearboxes per day
• Aircraft production similar in quality and
  complexity is on the order of 1000 per year

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Thermal Processing Issues

• Large parts require large furnaces
• Economic load sizes typically over 5,000
• Large teeth require deep cases
• Cycle times of 60 hours not uncommon
• Aerospace quality required at all steps

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Volume price pressure drive equipment purchases

• Customers want lowest possible costs
• Existing job shop equipment cant keep up
• New technology offers improved quality with
  faster cycle times

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Dramatic Cycle Time Reductions Possible

• Shaping an internal ring takes 30 hours
• Gashing takes 3 hours
• Hobbing a gear can take 8 to 10 hours
• Gashing takes less than 2 hours

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Big non-chip making investments needed

• SPC needed on everything
• 100 magnaflux, UT, nital etch typical
• Shot peening required on everything
• Full met lab checks on every furnace load
• Verification of geometry requires big CMM
• Everything that can be inspected must be
  inspected

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Big investments needed in QC
Super Finishing required on many components To
achieve 4 to 8 AA surface finish
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An Industrial Challenge worthy of a great nation!

• Potential to transform the economy
• Positive environmental impact
• Huge export market available
• US was once the world leader in wind energy and
  can be once again
• Plenty of room for innovation at all levels of
  the business

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