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 processingis 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
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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
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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 components
To achieve 4 to 8 AA surface finish
An Industrial Challenge worthy of a
great nation!
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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