The Balder roller coaster at the Liseberg Amusement Park in Gothenburg, Sweden, is said to be one of the best in Europe – but was in urgent need of a high strength and corrosion resistant screw solution following two failed fastener solutions.
The Balder roller coaster was opened in 2003 with 8.8/10.9 carbon steel screws that began corroding, rusting and braking after only a few years. Liseberg started replacing the carbon steel screws with A4 screws, but these were too weak and also started breaking.
A strong but flexible and fatigue resistant screw was needed to secure the roller coaster rails to the wooden frame, which expands, contracts and moves throughout the different seasons. Corrosion resistance was also necessary to deal with the impregnated wood, and the corrosive local environment caused by vehicle emissions from the adjacent E6/E20 highway and salt water from the nearby sea.
The BUMAX solution
The Liseberg amusement park approached BUMAX for a solution, and 355 mm long specially designed M10 BUMAX® 88 screws were used to successively replace the existing carbon steel screws between 2009 and 2018.
As of March 2019, no issues have been reported with the BUMAX® 88 screws installed.
BUMAX partner collaboration
BUMAX cooperated with Liseberg to develop a custom-made BUMAX® 88 screw specifically for use on the Balder roller coaster.
One of the main reasons why BUMAX® 88 was a success compared with the fasteners Liseberg had previously tested was its excellent fatigue resistance. Third-party tests have shown that standard BUMAX® 88 can withstand 10 million cycles at a preload stress of 400 MPa with no screw fracture. This compares with 0.4 million cycles before an A4-80 screw fractures.
