A wind turbine manufacturer approached us with a specific need: to improve the reliability and life of the pitch control systems in its turbines. These systems adjust the angle of the blades to make the best use of the wind, and they depend on compression springs that hold a steady force.
The Problem
The existing compression springs in the pitch control mechanisms were failing prematurely. There were three causes: the spring force was inconsistent, the springs corroded in harsh weather, and they fatigued under the continuous adjustments the system makes.
Requirements
- Environment: offshore turbines, with saltwater corrosion, high humidity and temperature swings.
- Force: a consistent spring force with minimal relaxation over time, so pitch control stays precise at changing wind speeds.
- Life: the ability to withstand constant small adjustments for years without loss of performance.
Our Solution
Material
After analysis we selected Inconel X-750, a nickel-chromium alloy. It resists corrosion in a marine atmosphere, and it resists relaxation, meaning it keeps its force under long-term load. Both properties address the failures seen in the original springs.
Surface Treatment
We applied a two-step surface treatment. The springs were first passivated to protect against corrosion. They then received a PTFE (polytetrafluoroethylene) coating, which lowers friction and adds a second barrier against corrosion.
Manufacturing
The springs were produced on CNC coiling machines for high dimensional accuracy. Each spring was inspected for conformance to the specification using laser measurement systems.
Testing
- Salt spray test: a 500-hour salt spray test simulated offshore conditions and confirmed the corrosion resistance.
- Load test: each spring was tested for load consistency, and the deviation was below 2%.
- Fatigue test: more than 100,000 compression cycles simulated operating conditions, with negligible loss of performance.
Results
- The new springs held a consistent force, which made blade pitch adjustment more accurate.
- The pitch control systems lasted longer and needed maintenance less often.
- The customer reported that the springs exceeded its expectations, and the project led to a long-term partnership.
What This Project Shows
Offshore, a spring has to resist corrosion and keep its force for years with nobody checking on it. The combination that worked here was a corrosion-resistant alloy, two layers of surface protection, and testing that copies the real environment before the parts are shipped.
If you need compression springs for marine or outdoor equipment, contact us through the contact page, or see our custom compression springs.
