When Siemens began to investigate composite materials for nacelles used on its new 6MW offshore wind turbines, one of the key things it looked at was a composite maintenance hatch designed to replace a steel panel, and the traditional bolt fixings were used to lock and unlock it. This required two persons to perform the operation – one inside and one outside the nacelle. Clearly ease of access and its related safely were problems to be solved, in addition to reducing maintenance costs.
Siemens’ nacelle suppliers approached Bighead Bonding Fasteners, and together they developed a solution was developed. While the standard range of over 400 mild steel and stainless steel bigHeads provide efficient and effective discrete fixings, whether embedded or surface bonded to composite materials, there are some applications that benefit from a design approach where the characteristic bigHead welded fixing is engineered and adapted to actually improve the final design, to enhance its performance or reduce costs – and even to facilitate increased safety. Such was the case here.
By surface bonding the 316 marine grade stainless steel bigHead to the outer skin of the nacelle and passing the threaded stud section through its composite structure, the panel is easily secured or removed by a single person from the much safer interior of the structure. The bigHead’s large perforated head allows a generous flow of adhesive to firmly secure it in position and its outer surface includes an over-moulded insulation layer that safeguards the nacelle against lightning strikes as well as match its colour.
Bighead worked with the customer through a stringent development stage – prototyping and extreme testing of the solution against the harsh conditions that the offshore wind turbines need to endure until a final design was agreed. Now in its third year of supply, the solution has been thoroughly field proven. Like all bigHead’s produced at the company’s Verwood, UK factory, every production batch is tested and documented with completely traceable results as part of the manufacturers ISO 9001:2008 quality management system.
Bighead Bonding Fasteners has been manufacturing its distinctive and leading brand of discrete bonding fasteners for over 50 years and has extensive experience across a wide range of industries where formed and moulded composite products require discrete and completely secure fixing.
Applications range from carbon fibre panel fixing in specialist and luxury car production to building and construction, railway carriage construction, marine and boatbuilding and more.
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