Process for producing a composite food casing

A process for producing a shirred tubular composite casing, characterized in that the process comprises steps where an inner casing is pulled through a pipe having a calibre disc at the exit end of the inner casing and having a shirred outer casing arranged thereon, while simultaneously pulling the outer casing over the calibre disc in the travelling direction of the casing, and further over the inner casing opened to have a tubular form and pressurized, followed by pulling the combination of the outer and inner casings onto a shirring horn using feeding cylinders of a shirring machine, said shirring machine shirring the composite casing to give a compact tube, which is cut to sticks of desired lengths.