First Wind Farm Uses CNC Onsite and We4Ce Technology for Root-End Repair

Danish precision machining specialist CNC Onsite and Dutch blade expert We4Ce have completed their first joint project transferring repair know-how to a wind farm in South Asia. In May, the customer’s technicians were trained to independently repair loose inserts in the root ends of 26 turbine blades. This was the first time the companies' new repair method was put into practice. The method offers a cost-effective and sustainable alternative to full blade replacement by eliminating the need for external transport and potentially reducing blade waste.

CNC Onsite’s specially built precision machine removes the damaged inserts directly on-site, allowing the wind farm’s technicians to apply We4Ce’s patented "Re-FIT" method for mounting and securing new inserts. Prior to the launch of the 50 MW project in South Asia, the technicians were trained in the repair method at We4Ce in the Netherlands and in operation of the precision machine at CNC Onsite in Denmark. The technology is delivered under a licensing model, enabling wind farms to carry out major blade repairs with their own service teams.

Following the training, the customer’s service team in South Asia established a temporary workshop directly in the wind farm, where extensive repairs were carried out over several weeks under the supervision of CNC Onsite and We4Ce.

"Securing and now executing this first contract for our new insert replacement method directly in the wind farm was the result of solid engineering with a focus on practical application," says Arnold Timmer, Managing Director of We4Ce. "We got the idea in early 2022 following a project with a customer in India and then spent three years developing and testing the solution."

By applying the repair technology, the customer will now be able to replace more than 1,000 defective inserts. The process combines precision boring, a specialized fastening method, and installation of replacement inserts, resulting in a component that is nearly as good as new, designed not only for reliable performance but with a projected lifespan of up to 20 years. This process represents a significant improvement over conventional repair methods.

Repair Technology: A Future Opportunity for Operations and Maintenance (O&M)

With operations and maintenance (O&M) being critical to the long-term performance of wind turbines, "remanufacturing" - restoring components to the same or better quality than their original condition - is likely to shape the wind sector’s approach to maintenance in the years to come.

Onsite replacement of blade root inserts is an advanced process requiring the right equipment and components to ensure a strong mechanical connection.

Three industrial work tents, each 100 m² in size, were set up at the wind farm. In the first tent, the blade was bored; in the second, the insert was replaced; and in the third, final finishing and quality checks were carried out.

The We4Ce and CNC Onsite method offers significant advantages: up to 60 percent cost savings, reduced downtime, and environmental benefits by eliminating potential blade waste and the need for transport, which typically involves high logistical costs and CO₂ emissions.

Efficient Boring in Fiberglass Rotor Blades

CNC Onsite designed and built a custom machine for boring out defective inserts from the root ends of turbine blades. The machine produces precisely dimensioned holes tailored to fit the new inserts.

“Boring into fiberglass wears down drill bits quickly, making the process demanding and time-intensive. As part of the project, we developed special drill bits to ensure high precision and efficiency,” explains Søren Kellenberger, Partner and Sales Director at CNC Onsite.

Infusion Technology Ensures Durable Insert Bonding

We4Ce uses its patented infusion technology to securely fasten the replacement inserts. Through an inlet pipe, epoxy resin is injected into the insert while a vacuum ensures even distribution around the cavity.

The insert at the root end of the blade is a safety-critical component that connects the blade to the hub. In certain blades, the insert is embedded in polyester. If the material shrinks or distributes unevenly during manufacturing, microcracks may develop, which over time can lead to larger fractures.

This weakens the bond and increases the risk of insert detachment - potentially causing serious blade damage.

We4Ce and CNC Onsite are currently preparing several upcoming projects with significant potential, including in Brazil and the USA.

About CNC Onsite

Headquartered in Vejle, Denmark, CNC Onsite designs, builds, and delivers high-precision mobile machining equipment for wind turbines, including offshore foundations. The machines can be built for a variety of tasks. CNC Onsite serves the onshore and offshore wind sector, providing solutions such as large-diameter steel flange machining and blade root-end processing; specialized repair services for yaw rings, rotor locks, generator shafts, bearing housings, removal of broken bolts, and thread hole repairs.
www.cnconsite.dk

About We4Ce

Headquartered in Almelo, the Netherlands, We4Ce has more than 25 years of experience in supplying rotor blade technology — both for manufacturing and aftermarket applications. The company specializes in blade design, insert technology for blade roots in sizes M20–M42, and solutions for segmented blades with replaceable root sections.

In the aftermarket, We4Ce performs Root Cause Analyses (RCA) of blade failures and offers a licensing model for its patented Re-FIT remanufacturing method for blade root inserts. In close collaboration with wind farm owners, We4Ce’s research lab conducts fatigue and extreme load testing on various sizes and parameters, supporting the development of inserts for OEMs.

We4Ce also collaborates with TNO’s testing institute for large component trials and certification through bodies such as TÜV and UL.

Media contact

Dr. Malene Conlong
M.conlong@mollerint.dk
+49151 53930015

This text has been translated to English by Energy Cluster Denmark.