Abstract: The method produces a flat spiral link assembly from at least four synthetic resin monofilament helices wound winding to winding which are simultaneously supplied for meshing engagement. Before being meshed the helices are stretched to at least three times their length and are thermoset in stretched condition. The alternatingly right-hand and left-hand helices are caused to mesh in zipper fashion and are interlocked by pintle wires. In order to facilitate the insertion of the pintle wires the helices are extended by about five percent. The apparatus for performing the method comprises two feed rolls forming a first roll nip through which helices are passed to a heating chamber. Draw-off rolls withdraw the helices from the heating chamber at least at three times the peripheral speed of the feed rolls. The apparatus also comprises a shunt for joining the helices and a device for inserting the pintle wires.