CNC Onsite delivers professional, precise machining solutions for repair or as part of manufacturing, including blade root inserts, yaw ring (in-situ) and flanges up to 10-m.
several locations
Precision in the field: CNC Onsite’s mobile machining extends wind turbine lifespan
As wind turbines age and grow in size, the demand for field-based precision repairs is increasing. Danish company CNC Onsite is meeting that challenge head-on with innovative mobile machining solutions that deliver factory-grade accuracy – directly on site, offshore or onshore. With expertise in blade root repair, yaw ring repair, and flange milling, the company is helping wind operators extend turbine life, cut maintenance costs, and reduce environmental impact.
Blade root repair: Restoring critical interfaces
In collaboration with Dutch rotor blade expert We4Ce, CNC Onsite has
introduced an advanced in-field method for repairing loose blade root bushings – a common failure in the connection between blades and wind turbine hub. In a recent 50MW project in South Asia, the partners trained local technicians to carry out the process independently, using CNC Onsite’s portable precision machine and We4Ce’s patented bushings and insertion system.
Conducted in a mobile field workshop in 2025, the method is delivering over 1,000 successful bushing replacements, restoring each to a likenew standard with a projected lifespan of 20 years. The result: up to 60 percent cost savings, reduced downtime, and no need to transport blades offsite – a major logistical, environmental and financial win:
Flange machining: Raising standards at scale
To meet the flatness demands of today’s large turbine flanges, CNC Onsite developed Goliath, a purpose build CNC-controlled milling machine designed for flanges between 6.5m and 10 meters in diameter. Deployed at Welcon, Goliath is currently machining 97 bottom tower flanges for Vestas’ 15MW turbines, as well as large-diameter flanges on transition pieces at CS WIND’s facility in Aalborg, Denmark.
The first flanges milled achieved an exceptional flatness of 0.21 mm
– far exceeding industry norms – and eliminated the need for manual
heat straightening. In addition to improving bolt integrity, the process offers design flexibility, time savings in production, and better long-term performance. Multiple Goliath machines are now operating across Europe in tower, transition piece and monopile applications.
The ability to meet fine tolerances consistently – 1 mm or less guaranteed – contributes to more reliable mechanical joints and lower maintenance costs, particularly in offshore conditions where bolt tightening is critical and access is costly.
Yaw ring repair: Precision without disassembly
CNC Onsite’s yaw ring repair service brings another major advantage: full restoration without removing the nacelle. As turbine fleets age, yaw ring teeth wear is becoming more common. CNC Onsite’s patented up-tower repair method removes damaged gear teeth and installs perfectly matched segments – all within the nacelle and without the need for external work, like disassembly. Now adapted for a range of turbine types, the method has restored more than 100 yaw ring segments across three continents.
Repairs are completed in days, reducing downtime, CO₂ emissions and costs. The service is supported by CNC Onsite’s technical center in Vejle, which includes a 2,000 m² workshop for machine development and testing.
Because the repair is conducted inside the tower and doesn’t depend on favorable weather, planning is more flexible. Technicians also benefit from improved safety conditions by avoiding heavy component handling or lifting operations.
CNC Onsite’s mobile solutions bring high-precision machining to where it’s needed most – in the field. As the wind industry faces increasing pressure to optimize assets, these innovations offer a powerful toolkit for long-term turbine performance.
