WCA September 2022

Technology News

Rosendahl’s infrared cross-linking section

Infrared curing for silicone The fire resistance of cables in public buildings, such as airports or hospitals, follows strict guidelines. In the event of a fire, to evacuate all people safely the basic functions of a building must stay intact for as long as possible. BS6387) are met by each safety cable produced on a Rosendahl silicone line. To make silicone cables resistant against high temperature, they need to be cross linked. Different processes are available to do this, but hot air or infrared curing are mostly used in new production lines.

space, and power consumption during production is around 30 per cent less. An infrared curing section typically consists of three zones. A shock oven “freezes” the silicone surface, enabling the use of support rollers without the silicone sticking. The remaining ovens are used for gentle cross-linking of the silicone to the desired degree. Each oven is temperature controlled, specified by the line control. Rosendahl’s infrared ovens are optimised for energy efficiency and easy handling. For safety reasons the ovens are designed to open automatically in case of an emergency. To simulate the cross-linking pro- cess Rosendahl has developed a math ematical model that provides relatively exact values for the process and produc tion speed. Together with the line con trol, this set-up ensures product quality with continuous quality monitoring. Rosendahl developed its first silicone extrusion line with infrared curing in 2014. Since then, several new lines have been installed worldwide. The company now offers different optimised line configurations for safety cables with diameters ranging from 0.25 to 300mm 2 . It also develops the optimised extruders with automatic stripe feeding, crossheads and curing ovens for effective and reproducible results.

Silicone’s high temperature resistance, low smoke emission, zero-halogen content and non-toxic substances make it a suitable insulation and jacketing material for cables used in fireproof applications such as elevators or alarm systems. The quality standards that need to be fulfilled for integrity (DIN 4102-12) and insulation (IEC60331, EN50200 and Certified reels Following five months of hard work, Jiangsu Qunye’s Reel & Skid, certified by DNV, has been exported. Qunye reels have been recognised by Norske Veritas, confirming the quality of the company’s products, and have been further acknowledged in the international marine field. Reels from Qunye are increasingly accepted by developed countries around the world. The company states that it always adheres to the best quality and the fastest delivery. Jiangsu Qunye Electrical Co Ltd www.qunye.com.cn

Rosendahl machines rely on infrared curing, which the company says is more efficient and flexible than other cross linking methods, with minimum scrap rates and easily controllable parameters. It is up to 15 per cent faster than hot air systems utilising the same floor

Rosendahl Nextrom GmbH www.rosendahlnextrom.com

Qunye reels are recognised by Norske Veritas

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September 2022