08 April 2014
08 April 2014
Together with partners from the industrial and university sector within the scope of the R&D collaborative project, ‘Design of a heatable tool made of fibre-reinforced composite with integrated surface temperature control,’ Norafin Industries has developed a range of electrically heatable nonwovens with applications in the composites industry.
According to Norafin, electrically conductive fibres incorporated within woven, nonwoven or knitted fabrics serve as electrically resistant heating elements. In contrast to resistance heating with discrete heating wires, textile heating elements transform electrical energy into thermal energy in a more even manner.
“The innovative, energy-efficient, functional heatable nonwovens distinguish themselves through short heating-up times in the low voltage range (U < 48V), low bulk, ease of use, good drapability, and homogeneous heat output and distribution during the heating-up and cooling-down phases” says Marc Jolly, Head of R&D of Norafin Industries.
The company says the nonwovens can be produced economically with spunlace and/or needle punch processes. By utilising different raw materials and process parameters the desired characteristics can be specifically engineered. By careful design and control of the quantityof electrically conductive fibres, the electrical resistance of the heatable nonwovens can be optimally adapted to the needs of the user. Relatively high surface temperatures of 100-130°C and short heat-up times of between 60 and 180s can be achieved with optimal nonwoven parameters and voltages U from 5-30 V.
Contact between the power supply and the heatable nonwoven is achieved via planar, flexible litz (braided, stranded) wire. This ensures a low contact resistance between the power supply and the nonwoven heating element and reduced incidence of hot and cold spots. Due to the physical characteristics of the nonwoven fabric even heat distribution is achieved even when moulded over complex shapes.
Norafin explains that development of innovative heatable nonwovens presents new opportunities for use in composites. The company is targeting applications such as low voltage heated panels and heated composite tooling. Marc Jolly says “When heatable nonwovens are used in place of conventional heating elements for heated composite moulds, due to the rapid heat up and homogeneous temperature distribution, the resin hardens more consistently and more quickly. This results in higher component homogeneity, improved surface condition and increased component quality. Also the productivity of the manufactured components can be increased significantly due to the relatively short heat-up and cool-down phases and consistently homogeneous, planar temperature distribution.”
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