Edge Pinning with Pinner Applicator
Cast film extrusion is utilized for a wide range of elastomers and polymers, like polyethylene (PE) and polypropylene (PP), commonly used in food and medical packaging. In this process, the polymer is melted into a viscous liquid and mixed with any required additives. The polymer melt is then extruded
through a die into a thin film that is directly deposited onto a chill roll. Extrusion temperatures are often 392°F (200°C) or higher depending on the specific polymer mix being extruded. The melt is rapidly cooled to a solid form by the chill roller.
The edges of a cooling cast film extrusion shrink inward (neck in) on the chill roller due to internal tensile forces. The neck in will result in a narrower, inconsistent web width causing more trimming to be required, more rejected product, or both. The tensile forces are nonuniform and can cause misalignment on the roll and lead to slack in the center of the film extrusion.
Installation of a Pinner Applicator on each edge of the extrusion just after the extrusion die will pin the cooling film to the chill roll. This will reduce neck in and slack by generating a uniform tensile force across the chill roll. The uniform horizontal forces also have the added benefit of creating a uniform
contact force on the roll, increasing the cooling efficiency of the roll. Powering the two applicators with a VCM-30 brings the versatility of current control mode. With a maximum output voltage of 30 kV, the VCM-30 and Pinner Applicators can be fine-tuned to provide maximum performance. Vertical space is often limited near the extruder die making the rotatable pins of the Pinner Claw ideal for edge pinning.