1359056 Seaming non-metallic sheet material LERNER MACHINE CO Ltd 29 Sept 1972 [1 Oct 1971] 45816/71 Heading B5K A device for welding and cutting plastics webs 17, 18 comprises at least one heating welking element 5 movable relative to an anvil 9, a blade 16 heatable by the passage of electric current therethrough and extending longitudinally of, and spaced from, opposite faces of the element 5 and the anvil 9, and means for causing relative movement between the blade 16 and the faces. As shown in Fig. 1, heating elements 5, 6 covered by barrier tapes 7, 8 are mounted on carriers 2, 3 spaced by a groove 4 on a sealing bar 1. The anvil 9 comprises arms 10, 11 having faces 12, 13 corresponding to the carriers 2, 3. A knife 14, comprising an electrically insulating holder 15 and a serrated or straight edge blade 16, is movable into the groove 4 which may be filled with resilient silicone rubber. Silicone rubber tapes may be provided on the faces 12, 13 or behind the wires 5, 6 which may be of round or flat cross-section. In operation, the webs 17, 18 are clamped between the bar 1 and the anvil 9 and a current impulse is applied to the wires 5, 6 to effect welding. The blade 16 is then heated and moved into the groove 4 to effect cutting. In a modification, Fig. 2 (not shown), the wire 6 and the barrier tape 8 are omitted. In a further modification (not shown), the knife moves from a gap in the sealer bar into a gap in the anvil.