Machining wind turbine hubs in less time

Countries across the Middle East are ramping up renewable energy investment, with some states aiming to have renewable sources account for more than 40% of their energy mix by 2020. Saudi Arabia, Kuwait, and Oman have each stated plans to produce at least 10% of their energy from sustainable sources by 2020. Whereas Dubai and Abu Dhabi set targets of producing 5% and 7% respectively of their energy from solar and renewable sources by 2030. MAG presents its latest MEGAFLEX machining system that blows away cycle time for wind-hub production. The patented three-spindle system machines wind turbine hubs in less than one shift, with estimated 1800-part-per-year capacity. System scales up high-volume automotive machining concepts for mega-size parts.

Astraeus Wind Energy's MAG MEGAFLEX machining system has passed its initial supplier qualification by completing "Operation 20" metal cutting processes in record time on a Clipper Windpower C96 turbine hub, one of the industry's largest. The unique system simultaneously machines all three blade faces, which enabled it to complete the qualification hub in less than one shift, a first in the industry. "Completing hundreds of features on this hub in such a short time, and meeting the extreme tolerances required, is a world first for U.S. manufacturing technology," said Astraeus President Jeff Metts. "The 18,144-kg (40,000-lb) spherical hub is about 3.6 x 3.6 m (12 ft x 12 ft) in size, with a blade bolt circle of about 2.5 m (8.2 ft). Operation 20 for this part included milling the blade faces, drilling and tapping or counter-boring more than 60 39-mm (1.5-in) holes per face, boring and drilling the bladepitch gear mounting surfaces, and cutting various other features. Tolerances on the part, which was laser inspected after machining, include 0.05mm (0.002-inch) true position on holes and ±1 degree on angles.

Conceived by MAG in 2009, the MEGAFLEX system's development was funded in part with grants from the Michigan Economic Development Corporation (MEDC), which audited and approved the progress of Astraeus in meeting its performance requirements. MAG developed the entire system on a turnkey basis, including the process concept, programming, machine systems and tooling package. The patent-pending MEGAFLEX design, which is based on three MAG FTR 5000 floortype boring mills surrounding a B-axis rotary table, simultaneously machines all three blade faces on a wind turbine hub in one setup, a concept widely used in mass-production of automotive components and small parts.

Unique features on the boring mills include a specialised tooling package utilising numerous extension tools, and a servo-controlled tilting A-axis on the W-axis ram. The tilting A-axis allows the ram to be positioned for a normal approach angle to the work face. This is required because the blade face of the hub is not always perpendicular to the hub's axis of rotation, but may be two to three degrees off, depending on the manufacturer.

Opportunities
By developing technology that is able to better withstand the dust, sand, wind, high temperatures and low water levels that characterise the desert environment in most of the Middle East, companies may realise a first mover's advantage to mass adoption. Market forces and a changing competitive landscape are providing compelling reasons to consider alternative sources of energy. As such, many short term and medium term opportunities will continue to surface and impact the GCC region.