High customer demands
The customer required a fastener solution to secure the wind turbine magnets on a new 6MW off-shore wind turbine model. A long design lifespan solution was required – ideally with no maintenance for several decades as part of a low-maintenance contract.
As the magnets cannot be entirely protected from the elements and the marine environment, a screw with excellent corrosion resistance was required. When in operation, the wind turbine magnets are also subjected to combined axial and radial forces, which puts high fatigue demands on the magnet screws.
The BUMAX solution
BUMAX® 88 M20x75 screws are a standard BUMAX product that was thoroughly tested for this particular wind turbine magnet fastening application prior to use. Each turbine uses 720 BUMAX screws to secure the turbine magnets in place.
BUMAX® 88 screws have excellent corrosion and fatigue resistance compared with other carbon and stainless steel fasteners – to meet the customer’s low maintenance requirements. The reliable and high-quality nature of BUMAX® 88 is also very important for fatigue resistance, as well as galling resistance compared with normal stainless steel screws that typically have galling issues.
As of February 2019, the customer has purchased screws for 66 turbines, with orders for a further 236 turbines to be installed in Europe and the US by the end of 2020.
BUMAX customer collaboration
Standard BUMAX® 88 screws were developed over 10 years in cooperation with a screw securing systems company and the main BUMAX distributor in France. Tests by the customer and BUMAX have shown exceptional results with the BUMAX® 88 screws coping with 100 million cycles.
The BUMAX® screws will realize cost savings for the customer through lower maintenance costs and less turbine downtime. The 300+ turbines installed and ordered, as well as future turbines, will lead to significant global savings for the customer in the coming decades.
Stainless steel is 100% recyclable and retains its original physical properties when recycled. This recyclability reduces the use of virgin material and lifecycle carbon emissions.
The low maintenance requirements will reduce the need for offshore wind turbine maintenance teams to conduct potentially dangerous screw replacement tasks.