6/30/2020 | 1 MINUTE READ

Bumax Fasteners Chosen for World's Largest Telescope

Originally titled 'Screw Manufacturer Chosen for World's Largest Telescope'
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Bumax stainless steel fasteners are being used for construction of the European Southern Observatory Extremely Large Telescope in northern Chile.

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Bumax, Swedish manufacturer of stainless steel fasteners, was chosen to supply thousands of high-strength, corrosion-resistant fasteners for the European Southern Observatory Extremely Large Telescope (ESO ELT), which is under construction in northern Chile.

The company received an order for more than 11,000 fasteners for the construction of the ESO ELT, which will be the world’s largest telescope when it goes operational in the dry Atacama desert in northern Chile in 2024.

The ELT is a reflector telescope, collecting universal light using a massive curved mirror that is 39 meters across, which is three times the area of the world’s second largest telescope. A mirror that size is too large to be made from a single piece of glass, so it will consist of 798 individual hexagonal segments, each measuring 1.4 meters across and driven by electrical motors for fine-tuning. The segments will work together as a single huge mirror to collect 100 million times more light than the human eye.

Bumax fasteners are used to fix the nearly 800 telescope mirrors to all the segment supports. There are 12 pieces of 10-mm long Bumax 109 M6 bolts per segment used for more than 900 segments in total (the 798 support segments, plus an additional 133 segments for a continuous swapping process to allow the mirrors to be cleaned and coated while the ELT stays operational).

The ELT is presently under construction by the Dutch company VDL ETG Projects in the Netherlands. “Standard stainless steel bolts lack the strength required for the ELT,” says Michael Evers, project manager at VDL ETG. “We required a 10.9 strength bolt and with the corrosion resistance of stainless steel. Bumax offered us the perfect solution.”

“The high-strength Bumax 109 fasteners prevent damage to the mirror segments, which is very costly,” Evers says. “Their corrosion resistance is also essential as the fasteners are sometimes open to the elements and will reduce future maintenance requirements.”

The bolts are a customized product that required special tools to manufacture. At the customer’s request, the bolts have been coated with a special surface treatment commonly used for fasteners used in telescopes.

“This order is yet another testament to Bumax being able to provide the very best fasteners for the most demanding applications,” says Patrik Lundström Törnquist, managing director at Bumax. “We have also been trusted with supplying fasteners for the CERN accelerator in Switzerland, satellites, submarines and more.”


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