Bushings are critical load-bearing components that secure the blade to the turbine hub with bolts. Each must withstand forces up to 1000kN—equivalent to 50 passenger cars pulling on the blade at once

Vejle, Denmark, 3 April 2025 – From April 8–10 at WindEurope, Danish mobile machining specialist CNC Onsite will present its on-site repair method for loose blade root inserts.

In collaboration with Dutch rotor blade designer We4Ce, CNC Onsite uses a portable precision machine to replace inserts directly at wind farms. This cost-effective solution eliminates rotor blade transport to the manufacturer, reduces environmental impact, and minimizes downtime.

Loose blade root inserts previously could only be repaired at the rotor blade manufacturer, leading to costly logistics and long downtime. Operators therefore often had no choice but to purchase a new blade or scrap the entire turbine.

The new method cuts costs by up to 60 percent and eliminates months of downtime. Older turbines benefit from a longer lifespan since costly factory repairs or scrapping are no longer necessary. A safety-critical component, blade root bushings, also called inserts, connects the rotor blade with the turbine hub.

The repair method combines We4Ce’s expertise, who supplies its patented replacement insert, ”Re-FIT” along with its infusion technology to fix the component reliably. CNC Onsite extracts the loose bushings with its custom-built precision machine.

Damage to blade root bushings warrants more research. “We believe this issue is rising and it affects turbines of all sizes and ages, ranging from 1.5MW to 3MW and from 40-m to 60-m blade lengths. Usually, it occurs after the warranty period,” says Soren Kellenberger, sales director and partner of CNC Onsite.

Defective bushings, glued into the blade during manufacturing, are complex to remove and replace with precision. We4Ce’s patented solution ensures a strong mechanical connection and uniform bonding, fixing new inserts reliably.

With the new repair method, the rotor blade is dismounted on-site. Multiple blade sets can be repaired within weeks.
Previously, repairing a blade meant costly shipping to the manufacturer, unnecessary CO2 emissions, and extended downtime—cutting into annual yield.

The patent of the replacement insert from We4Ce covers the bonding method and design. An inlet tube placed into the hollow of the bushing is used to infuse epoxy resin into the extremities of the bushing where a proprietary steel resin dispenser has been fixed. The resin is then evenly distributed around the outside of the bushing using vacuum processing, which allows the bonding material to flow uniformly up towards the flange of the bushing. The chosen diameter of the circular dispenser aids the centering and precise placement of the component, previously a challenge.

The solution is suitable for wind parks with more than 10 damaged blade roots. This calculation includes the setup costs and use of a specialized CNC on-site machine drilling out the loose inserts. Loose bushings are usually detected during inspection of the blade root connection. Cracks in the sealant between pitch bearing and blade root can indicate a loose bushing.

As the wind industry is calling for a ban on the landfilling of decommissioned blades in Europe from 2025, the new repair solution from We4Ce is expected to be a valuable alternative to scrapping.

Bushings are an important structural load-bearing component, which connects the blade to the wind turbine hub via bolts. Each bushing must have sufficient bonding strength capable of withstanding forces of up to 1000kN, the equivalent force of up to 50 passenger cars pulling the blade at the same time.

On stand E-E80, CNC Onsite will present its precision machining capabilities at WindEurope, Copenhagen, 8-10 April 2025.

For more information, visit www.cnconsite.dk.

Media Contact:
Dr. Malene Conlong
Moller International (for CNC Onsite)
+49 171 699 2650
M.conlong@mollerint.dk