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Dutch rotor blade expert  (Almelo, Netherlands) and Danish precision machining specialist  (Veijle) have completed a joint project to transfer blade repair expertise to a wind park in South Asia. In May 2025, the companies trained the customer’s technicians to independently repair loose blade root bushings on 26 turbines — marking the first in-field use of the partners’ new remanufacturing method. The approach offers a cost-effective, sustainable alternative to full blade replacement by eliminating the need for off-site transport and reducing blade waste.

The blade root bushing, or insert, is a safety-critical component that connects the rotor blade to the turbine hub. In some blades, polyester resin is used to embed the bushing, though it is more sensitive to shrinkage than epoxy resin. For example, a higher volume of resin between the unidirectional bar and bushing shrink more than thin layers. This inconsistent shrinkage in thin layers, especially between the root laminate and bushing, can lead to the formation of microcracks, reducing the bonding surface and increasing the risk of the bushing loosening, potentially leading to blade failure.

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In addition to these challenges, replacing bushings as an aftersales activity is a complex process, requiring precise removal and reinsertion for a strong mechanical bond. With operation and maintenance (O&M) crucial to long-term turbine performance, remanufacturing — restoring parts to equal or higher quality than the original condition — is likely to shape how the wind sector approaches maintenance in the years ahead.

CNC Onsite designed and built a custom machine to drill out defective bushings from the rotor blades’ composite laminate, creating accurately dimensioned holes for replacements. “Drilling in fiberglass is typically hard on the tools causing them to wear out quickly. That is why as part of this project, we developed special drills to achieve high precision and efficiency,” explains Soren Kellenberger, partner and sales director, CNC Onsite. 

Once damaged bushings are removed, We4Ce applies its patented infusion technology to fasten the new replacement bushing in place, ensuring exact centering. Epoxy resin is infused through an inlet tube into the base of the bushing, while vacuum processing ensures even distribution around the cavity.

Ahead of the 50-megawatt project, park technicians were trained at We4Ce’s laboratory in the Netherlands on the repair technology, and at CNC Onsite in Denmark on operating the precision machine. Delivered under a licensing model, this technology transfer enables wind parks to carry out major blade repairs using their own service teams.

Following their training, the South Asian service team set up a field workshop at the wind park and, under the supervision of CNC Onsite and We4Ce, carried out large-scale repairs over several weeks. Three 100-square-meter industrial work tents housing a rotor blade were set up as clean environments. In the first tent, one blade was drilled; in the second, the bushing replacement was carried out; and in the third, final flattening was completed.

“Securing and completing this first contract for our bushing and insertion method is the result of fine engineering for practical application,” says Arnold Timmer, managing director of We4Ce. “We first conceived the idea in early 2022 after an initial job with a client in India, and then spent 3 years developing and testing the solution.”

By adopting the remanufacturing technology, the customer will restore more than 1,000 bushings. The process combines precision milling, a specialized fixing method and the installation of replacement bushings to produce a like-new component engineered for reliable performance over a lifespan of up to 20 years. 

This approach represents a significant improvement over conventional repair methods, with up to 60% in cost savings, reduced downtime and environmental benefits from eliminating potential blade waste and blade transportation, which would typically incur high logistical costs and CO₂ emissions.

We4Ce and CNC Onsite are currently preparing for upcoming projects with significant potential, including in Brazil and the U.S.