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Plastic Slitting Process

Several plastic products are manufactured in wide sheets that require slitting according to its particular use. The process of plastic slitting is based on the type and thickness of the plastic and the sharpness of the blade edge. Plastic slitting is involved in the production of items such as adhesive tapes, polyester film, photographic film, acetate and holographic film.

  1. Slitting

    • Slitting involves the cutting of a wide plastic sheet into several smaller pieces by passing the sheet lengthwise through a slitter. The slitting process is divided into three methods that vary characteristically. These include the shear cut, razor blade and score cut method. Debris produced during slitting is a cause of concern, as it may stick to the plastic surface, causing a disruption in operation or a defective product.

    Shear Cut

    • Machines using the shear cut method have two rotary blades that function similar to a pair of scissors, producing a clean and smooth cut. The sheering force of the blades is adjusted according to plastic thickness, and the method is generally applied to polyester material. The shear cut method has a high cutting rate with a fine cutting-edge quality that produces less debris. Installation and maintenance, however, is more expensive than other methods.

    Razor Blade

    • In this method, the plastic is wrapped around a grooved roll and the razor blade is clamped to a stationary bar, allowing the blade to rest firmly in the center of the groove, where it cuts the plastic. This reduces blade shifting, thus enabling an accurate cut. It also prevents the damage to the blade from touching the side of the groove. The razor blade method is mainly used for soft plastics such as vinyl, polyethylene, and polypropylene.

    Score Cut

    • Score or crush cut is considered the oldest known cutting method. It involves slitting plastic with a slightly dull knife edge. The edge of the cutting knife is pushed through the plastic and onto a platen roll, with all three moving at the same speed. As this method produces considerable debris, it is not used for light plastics or paper. It is best used for plastics coated with pressure-sensitive adhesive.

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