Patent ID: 8875478

Claim:
An in-line method of forming and filling a flexible package, comprising: determining heat capacity and thickness of a flexible film and heat capacity and thickness of a semi-rigid strip, directing a web of the film and the semi-rigid strip in a machine direction; folding the web of film to match web edge sections against respective sides of the semi-rigid strip to form a pair of opposing walls with the semi-rigid strip there between; determining a differential of pressure and temperature to apply to respective web edge sections to seal one edge section but not an other edge section of the pair of opposing walls; and attaching the strip to only one of the edge sections of the pair of opposing walls by controlling directly applied differential heating and pressure according to the determined differential heat capacities and thicknesses, without an intervening buffer plate, to opposing walls of the pair to selectively seal one wall but not the other to the semi-rigid strip to define an opening between upper edges of the opposing walls.