Mass Flow Screw Feeder for Metering Waste Plastic

General Description

Pactiv Corporation manufactures household plastic trash bags and other plastic film products. Reject material is shredded and blown into a hopper where it is metered by a multiple-screw live bottom feeder back into the system to be recycled and turned into useable product. The reject material is extremely light, very thin, and shredded into strips. The product bridged in the existing screw feeder causing production problems. The existing screw feeder design “rat-holed” or tunneled through the product rather than provide consistent metering. The product would also “ball up” and plug at the discharge of the screw feeder. KWS provided a complete redesign of the screw feeder and hopper that eliminated all of the existing problems.

Design Parameters

KWS Advantages

KWS engineers visited the plant to assess the problem and work with Pactiv Corporation to resolve their difficult conveying problem. Existing plant equipment and layout as well as the Customer’s concerns, needs, and goals were considered when developing the new system design. Working together, Pactiv Corporation and KWS were able to provide a successful and effective solution.

Special Features

KWS engineers designed and manufactured a “mass-flow” cone screw feeder specifically for their application. The special mass-flow screw design utilized the concepts developed by Jenike & Johanson and allowed the product to draw evenly across the entire length of the screws and eliminated the bridging and “rat-holing” problem. The hopper was redesigned with vertical walls to prevent bridging of product over the screws. The combination of the hopper redesign and the mass-flow screw design resolved Pactiv’s production problems. The product now discharges evenly from the hopper at a constant feed rate.