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