Investment in technical center and resources has expanded services, benefiting wind turbine owners worldwide

VEJLE, Denmark, 17 March, 2025 - CNC Onsite, a Danish mobile machining expert, has extended its in-situ yaw ring repair service, which can now handle a range of common wind turbine platforms. Since nacelle layouts and working space around the yaw ring differ, each turbine type requires a custom machine setup. With the expanded service, CNC Onsite meets the growing demand for its cost-effective repair over replacements.

By conducting repairs up-tower, CNC Onsite eliminates the need to disassemble the nacelle using cranes—a benefit both for the environment thanks to lower CO2 emissions and for technicians thanks to improved health and safety.

"The number of turbines nearing the end of their design life is increasing. Therefore, even though the percentage of turbines with yaw ring gear issues is relatively low, the total number of turbines that can benefit from this solution is increasing. This, and the rising interest in lifetime extension has led us to offer the repairs across more wind turbine platforms," says Soren Kellenberger, sales director and partner, CNC Onsite.

To serve the most common wind turbine manufacturers, CNC Onsite has invested in additional engineering resources to develop its popular up-tower yaw ring repair service. Two years ago, CNC Onsite established a technical center in Vejle, Denmark, housing mechanical and electrical development as well as a 2,000 square-meter workshop to test and validate its repair methods.

Proven in the field across three continents, CNC Onsite's portable machines have been used to install more than 100 new yaw ring segments, equivalent to 600 teeth, on offshore and onshore turbines.

The toothed yaw ring gear keeps the rotor blades aligned with the wind direction for maximum power generation but over time, its teeth can wear down or break. Potential causes include sustained loads or unpredictable wind events. Ignoring yaw ring tooth damage doesn't just reduce energy production—it risks wider wear on the rotor blades and drivetrain, potentially leading to costly failures.

Now available for yaw rings for a range of wind turbine types, CNC Onsite's yaw repair service costs a fraction of replacing the entire yaw ring, the conventional alternative. The patented repair service restores yaw rings in days, whereas replacing the entire component can take weeks.

The proprietary machine incises the damaged yaw teeth to extremely fine tolerances, leaving a pocket with dimensions that fit the new replacement segment exactly.

Because the repairs are conducted inside the tower, timing does not depend on favorable weather conditions. The nacelle is not disassembled but stays in place, reducing costs while also benefitting health and safety— handling large turbine components poses a safety risk to technicians. Additionally, potential damage to the blades caused by the disassembly is eliminated.

Repairing the yaw ring up-tower to the required precision is complex due to its location, where working space for both the machine and technician is often limited. CNC Onsite designed its machine for modular transport for easy transport and reassembly up-tower

About CNC Onsite
Headquartered in Vejle in Denmark, CNC Onsite designs and delivers high precision mobile machining for wind turbines including offshore foundations. Machines built by CNC Onsite are designed to be flexible using its proprietary "building blocks" approach, which means machinery can be built to match a range of tasks. CNC Onsite serves the onshore and offshore wind energy sector delivering as standard solutions: machining of large diameter steel flanges and blade root ends; specialized repair services covering yaw ring, inserts in blade root, rotor lock, generator shaft, bearing housing and threaded holes. Removal and replacement of worn and broken bolts round off the offering.