Belgian extrusion die maker Verbruggen NV has developed a three-manifold die for films with up to five layers that is suitable for biaxial orientation lines.
Elements in the middle of the die controlling gap width are ``push only,'' but those at the sides are push-pull for better thickness control along the edges of the film.
The lower lip also can be made flexible at each end, with manually adjustable push-pull elements that are set in intermediate positions with respect to the elements on the upper lip. The company featured the die at K 2004 in Dusselforf.
The die can be equipped with cooling by either air, which is cheaper, or oil, which is more effective. Exchangeable inserts in the manifolds can be used to adjust the width of each layer.
The first die has gone to Iranian company Shimianeh Co. of Qazvin, according to Verbruggen, based in Temse.