The present invention relates to a welding machine for continuous welding of two layers of plastic film material together in a welding pattern, including a welding drum, welding means arranged on the peripheral surface of the welding drum that exhibits a welding pattern, a heating arrangement arranged to heat the welding means to a welding temperature, an endless welding band, a set of band guidance rollers comprising a first application roller and a second application roller arranged to apply the welding band to the welding means on the surface of the welding drum over a peripheral extend of at least 900° of the welding drum with a force radial to the welding drum in a first operational mode of the welding machine, the set of band guidance rollers comprising at least one displaceable tensioning roller for maintaining a tension of the welding band, a web guidance arrangement for guiding the two layers of plastic film material in between the welding drum and the welding band, and a control means for controlling the operation of the welding machine, wherein the machine comprises one or more separation rollers, and is arranged in a second operational mode of the welding machine to displace the one or more separation rollers from a first position thereof and in between the welding means on the peripheral surface of the welding drum and the two layers of plastic film material to a second position of the one or more separation rollers where the two layers of plastic film material and the welding band are separated from the periphery of the welding drum by means of the separation rollers. Furthermore is disclosed the use of such welding machine for forming pockets between the two layers of plastic film material, in particular closed pockets for air cushions.