21/07/2009

Tough stuff with silicone cable manufacturing

Indeed, several factors are building towards a peak in demand for production capacity. Vesa Koskivuo, product manager, cites examples "like the European standards being defined for safety cables and fire resistance, the growing activity in Arctic regions, and the increased exploration for resources. Cables need to resist to mechanical and chemical aggressions placed on them while remaining functional even in extreme conditions. We are ready to meet our customers' demand with an extrusion line especially designed for this toughened product."

Mr. Koskivuo summarizes the attractiveness of silicone cable. Flexibility across a wide temperature window is one key advantage. From Arctic sub-zero to oven hot temperatures, the cable retains its flexibility. "That is a key advantage when cable is laid across frozen tundra or installed in exposed structures." Another big plus is its behavior when burned. An outer crust forms around the conductor when consumed by flame, which helps it keep its dielectric qualities. "Cleary, its fire resistance characteristics make the cable worthy for safety applications, like emergency electrical systems and fire alarms. Plus, low smoke generation is an added advantage." Chemically stable, the insulation material is resistant to aging agents like UV, salt, heat and humidity. Cables previously insulated with silica are advantageously replaced with silicone. Silicone is tough and offers very good mechanical and chemical resistance.

Mr. Koskivuo qualifies the configurations suited for the process, "The EPL 25 lines are built and tailored for the individual applications in order to provide high performance production for the best known types of silicone cables. Manufacturers communicate the details of their cable constructions and we design the optimum package of extrusion, curing, cooling and wire reeling capacity to meet their requirements."

Maillefer's water cooled extruder for silicone is fed in bands or pellets. The crosshead is water cooled too in order to maintain the warmed silicone below its critical curing temperature as it is distributed around the conductor. A series of curing tunnels follow, where temperature can reach up to 750° C max. The usual downstream equipment is positioned after curing and includes a multi-pass cooling trough, measurement gauges, powder application and continuous winding on reels.