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Challenges in Wind Turbine Components
Charles D. Schultz, PE
Beyta Gear Service
Winfield, Illinois
What is going on in Wind Energy?
Activity on a national scale
Progress has been made but much remains to be done!
It is all about jobs!
Domestic Content Progress
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 aren’t “colorful” have wind potential
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
Towers & Blades
• Transport issues, 50 meter lengths & 40 ton weights
• High cost items• Potential for big
improvements• Big incentive to make
locally
Big Market, Long Term Potential
Where are the problems?
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
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
Big portion of value is in the Nacelle
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
Other Geared Products
Planetary designs predominate
Typical Gearbox Parts
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
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
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
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
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
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
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
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
Volume & price pressure drive equipment purchases
• Customers want lowest possible costs
• Existing job shop equipment can’t keep up
• New technology offers improved quality with faster cycle times
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
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
Big investments needed in QC
Super Finishing required on many componentsTo achieve 4 to 8 AA surface finish
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