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Cast Film Lines

Casting Machines and Cast Film Lines

A typical cast film line consists of an extrusion system, a casting machine, gauging system, surface treatment system, oscillation stand, and winder.  The cast film process is used to produce thin films, typically with low melt strengths. The die is usually positioned vertically above the main casting roll and the melt is pinned against the casting roll with the use of an air knife and/or vacuum box.

The casting machine is designed to cool the film and provide the desired surface finish on the film  and typically consists of two casting rolls. The main casting roll is used primarily to provide initial cooling and surface finish on the film. The secondary casting roll cools the opposite side of the film to provide uniformity in the film.  For embossed film applications, the casting roll has an engraved pattern and is nipped with a rubber roll.  A water bath and squegee roll are used for cooling the surface of the rubber roll.

The casting rolls are double shell style with spiral baffle, and have an internal flow design to maintain superior temperature uniformity across the width of the web. Circulating cold water from the heat transfer system cools the rolls. The sizes of the rolls are designed using Marshall and Williams Plastics' exclusive heat transfer program.

Once cast, the film passes through a gauging system to measure and control thickness. The film is usually surfaced treated either by a corona or a flame treater and passed through an oscillating station to randomize any gauge bands in the final wound product. Before the film enters the winder, the edges are trimmed for recycling or disposal. Automatic roll and shaft handling equipment are sometimes provided for winders with short cycle times.

M&W casting machines are also utilized for processing thicker materials for biaxial orientation applications.  We custom build machines that incorporate large diameter casting rolls, or multiple cooling roll designs to meet a wide range of materials and production requirements.  Also offering a wide range of pinning options, M&W casting machines are designed to meet your most demanding application requirements.

Contact us today for more information on plastic casting machines and cast film lines.