An apparatus for inflating and sealing packing cushions has a drive mechanism for feeding a preconfigured film material to a sealing mechanism in a flattened state without wrinkles in the sealing region in which a longitudinal seal is formed. A feed mechanism includes a drive mechanism for advancing the film along a path, a first guide member which contacts a first surface of the film material in a first longitudinal region, and a second guide member which contacts the first surface of the film material in a second longitudinal region laterally offset from and parallel to the first longitudinal region. In some embodiments, the first and second guide members are adjacent belts. In other embodiments, the first and second guide members are stationary guide members or “skis.” The sealing mechanism may include a rotary sealing element and opposed backing element, such as a belt or a wheel.