A film edge sealing device is disclosed herein which has a groove defining a base. The base of the groove of the edge sealing device is oriented at a skewed angle with respect to a longitudinal direction of the conveyor of the heat sealing machine. Edges of a thermoplastic sheet or two stacked layers of thermoplastic sheets are introduced into the groove of the edge sealing device and placed in contact therewith to both heat and melt the edges of the thermoplastic sheet(s) to form a bead and join the edges thereof to form an edge bead seal.

A form-fill-seal machine 100 has a pull-down belt mechanism 23, a vertical sealing mechanism 2, and a controller 29. The pull-down belt mechanism conveys a cylindrical film Fm. The vertical sealing mechanism applies pressure and ultrasonic oscillation to the cylindrical film which is conveyed by the pull-down belt mechanism, and seals the cylindrical film. The controller controls the pull-down belt mechanism, and the pressure and the amplitude of the ultrasonic oscillation applied to the cylindrical film by the vertical sealing mechanism. The controller applies pressure and ultrasonic oscillation to the cylindrical film immediately before reaching a first point in time when the cylindrical film begins to be conveyed. The controller changes at least one of the pressure and the amplitude of the ultrasonic oscillation applied to the film according to the speed of the film in a time period after reaching the first point in time.

The technology relates to a heat sealing system (400). For instance, the heat sealing system may include a sealer assembly (800) including a pair of heat sealing bars (830, 840) configured to generate heat seals. The heat sealing system may also include a positioning (900) assembly including a platform (910) and a motor (952). The sealer assembly may be mounted to the positioning assembly, and the motor may be configured to move the sealer assembly towards and away from an edge of a table (1600).