Abstract: An apparatus and process for obtaining the desired outside diameter for a tension-resistant core element, which includes assembling mixed filaments containing glass fibers and thermoplastic fibers, heating the bundle of mixed filaments to melt the thermoplastic fibers to form a matrix with the glass fibers embedded therein, then extruding an outer covering of the desired outside diameter for the core element onto the bundle. If desired, the melted bundle can be passed through a shaping device, which is preferably heated prior to extruding the coating thereon, and, subsequent to extruding, the extruded coating and bundle are cooled in the cooling device before being wound on a take-up drum or entering a stranding device for having communication elements stranded thereon.