Blown blown film extrusion film blowing blown film

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Unformatted text preview: ry. The film blowing process basically to form a thin tubular product that can be used directly, or slit to form a flat film. Blown Blown film process Plastic melt is extruded through an annular slit die. Air is introduced via a hole in the centre of the die to blow up the tube like a balloon. Mounted on top of the die, a high-speed air ring blows onto the hot film to cool it. The tube of film then continues upwards, continually cooling, until it passes through nip rolls where the tube is flattened to create what is known as a ' lay-flat' tube of film. Air inside the bubble is also exchanged. This is known as IBS (Internal Bubble Cooling). Cast Cast Film Extrusion • In a cast film extrusion process, a thin film is extruded through a slit onto a chilled, highly polished turning roll, where it is quenched from one side Blow Moulding Blow moulding is used to create hollow enclosed components and there are two basic types of technology extrusion blow moulding and injection blow moulding and stretch blow moulding. In extrusion blow moulding a parison or tube is produced by extrusion. A mould is then closed around the parison and the product is blown into the shape of the mould with compressed air. Extrusion Blow moulding Process The blow moulding machine is based on a standard extruder barrel and screw assembly to plasticise the polymer. The molten polymer is led through a right angle and through a die to emerge as a hollow (usually circular) pipe section called a parison. When the parison has reached a sufficient length a hollow mould is closed around it. The mould mates closely at its bottom edge thus forming a seal. The parison is cut at the top by a knife prior to the mould being moved sideways to a second position where air is blown into the parison to inflate it to the shape of the mould. After a cooling period the mould is opened and the final article is ejected.To speed production several identical moulds may be fed in cycle by the same extruder unit. The process is similar to injection moulding and extrusion. 1. The plastic is fed in granular form i...
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This document was uploaded on 03/14/2014.

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