Abstract: A method for extruding, stretching and sintering polytetrafluoroethylene in a single pass operation to form tubular articles of low density, low matrix tensile strength, sintered polytetrafluoroethylene and articles such as electric cable having low density, low matrix tensile strength sintered polytetrafluoroethylene insulation applied about a conductor by such method. A high reduction ratio rating polytetrafluoroethylene powder with a lubricant is extruded by an extruder having a low reduction ratio, and the extrudate is heated to remove the lubricant and is stretched prior to sintering of the polytetrafluoroethylene tube which is held in its previously stretched state during sintering.

Abstract: An insulated conductor for high temperature use and methods of manufacture thereof. The conductor is insulated by at least three layers of insulation, the inner layer being made of a perfluoroalkoxy, a polytetrafluoroethylene, an ethylene-tetrafluoroethylene, or a fluorinated ethylene-propylene resin compound, the second layer being made of a polyimide resin compound and the third layer being made of perfluoroalkoxy, an ethylene-tetrafluoroethylene copolymer, a non-hydrolizing, thermoset polyamide or a polyvinylidene fluoride resin compound. The layers are coated or extruded over the conductor and each other and preferably, the first layer is etched before the second layer is applied.

Abstract: A method for extruding, stretching and sintering polytetrafluoroethylene in a single pass operation to form articles of low density sintered polytetrafluoroethylene and articles such as electric cable (C) having low density, sintered polytetrafluoroethylene insulation (F) applied about a conductor (W) by such method.

Abstract: A die assembly for extruding a cover of a thermoplastic material over on plurality of bare or previously covered wires. The assembly comprises a two-part die body which holds between the parts a pair of removable cylindrical distributors, a removable wire guide and a removable die plate. The distributors are spaced from each other and the wire guide and the die plate are on opposite sides of the space between the distributors. Manifolds in the body parts supply heated thermoplastic material to flow channels on the peripheries of the distributors, and such channels extend to the space between the distributors. The wire guide has tubular passageways equal in number to the number of wires to be covered, and the die plate has an opening or openings dimensioned to correspond to the exterior dimensions of the cover or covers to be applied to the wires.

Abstract: A flat coaxial cable assembly comprising a plurality of parallel coaxial cables disposed in coplanar configuration, each cable being self-contained and with a center conductor, dielectric material around the conductor and a shield of conductive material around the dielectric material, a plurality of drain wires disposed between alternate pairs of adjacent coaxial cables, the drain wires having conductive contact with the shields of the pair of adjacent cables, and a sheath of insulating material encasing the cables and the drain wires with portions thereof on opposite sides of the cables bonded together by way of the spaces between the cables where the drain wires are omitted and at the sides of the outermost cables.