Manufacturing Excellence

Wind turbine gearboxes consist of large, high-tech components with a high power density. High-precision manufacturing and careful handling during assembly and pre-testing are mandatory for smooth and reliable operation in field conditions.

Core activities

  • In-house manufacturing of all gears and housings.
  • Specific in-house gear technology, based on invaluable know-how accumulated over decades of operational experience.

Key technologies

Heat treatment

  • 25 furnaces and 5 quenching baths.
  • Case hardening of all gears is standard, building upon three decades of dedicated in house know-how.
  • Details on gear hardening: in the gas carburising process the parts are heated above 925 degrees Celsius in a gaseous environment. The carbon penetrates the steel surface to a predetermined depth. In the next step, the temperature of the component is lowered to 850 degrees Celsius and the parts are then quenched in an oil bath. This sudden temperature drop – known as the chill – gives the material the required hardness. Finally the parts are annealed to make them more ductile.

Gear grinding

  • Final gear grinding and polishing stages based on advanced semi-automated machines, jointly developed by ZF Wind Power and its industry partners.
  • Details on gear grinding: the grinding operation involves a fast rotating tool with an extremely hard surface, shaped and sized to exactly match the final spacing between two gear teeth in mesh. After a few grinding cycles, the tool is re-measured, dressed again and brought back to its exact initial shape and size before engaging into the next cycle.

Machining of large castings

  • In-house manufacturing operations on large castings: Cutting, drilling, boring, tapping, turning, grinding.
  • Housings, covers and lantern housings, planet carriers, torque arms.
  • Machine park of more than 20 CNC state-of-the-art machining centres.

Operational excellence

  • Subsequent gearbox production steps conducted in separate manufacturing or assembly areas.
  • Each new process step characterized by gradually stepped-up environmental cleanliness requirements.
  • Quality measures guarantee required component cleanliness, preventing manufacturing residues to damage precision components like bearings, polished gear surfaces or contaminate gearbox housings before or during assembly.
  • For compliance with tight manufacturing tolerances, temperature in clean areas is kept at a constant level, with fluctuation only allowed within a narrow, strictly controlled bandwidth.
  • After gearbox assembly, each unit is first oil flushed – a process aimed at removing remaining particles from the manufacturing process and other remaining contaminants.
  • Factory-testing of each produced gearbox for about ten hours.

Quality and innovation in production

  • Innovation is not only limited to Research & Development, but is equally important in the manufacturing processes and methodologies.
  • Year after year improving of productivity, delivery times and quality.
  • Current quality processes include quality control of gears & castings, with a measuring precision up to 1 µm in climatized rooms, for dimensions up to 4,000 x 5,000 x 2,000 mm.