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CARBON FIBER

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EXTRUDER DIES

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  EXTRUDER DIES Extruder Sheet and Cast Film The convention between cast film and sheet is that film is less than 0.01 inch thick and sheet is more than 0.01 inch thick. The key components in a sheet/film extrusion line are: die, three-roll stack or cooling rolls, puller or nip rolls, and windup or sheet stacking system. The sheet die should uniformly distribute the polymer melt across the  entire die width. This is to provide a uniform melt thickness and polymer flow to the three-roll stack. Die width typically range from approximately 24-120 inches (0.6-3 meters. Cast film/sheet is produced using a multiple roll stack. Depending on the thickness, film is wound in continuous rolls and sheet is cut to length and stacked. The die is designed to fit between the rolls in a three-roll stack and lay the sheet down on the roll. Roll diameters generally range between 8 and 16 inches. Roll stack designs are simple 'up' or 'down' stacks to control the entry and exit angle and th...
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HOT RUNNER SYSTEM

  INTRODUCTION Multicavity injection molds can be built to make over 100  parts per cycle. Each part cavity is filled with melt through sprue and runners. As the attached sprue and runner cools down with cooling of plastic part, the sprue and runner comes out along with the plastic product when the product is ejected from the injection mould . The runners has to be seperated from the moulded plastic part which involves handling and regrinding of the sprue and runners. HOT RUNNER SYSTEM Unlike cold runners they are heated channels that keep the plastic molten during the entire cycle. HEATING MECHANISM Runners are kept hot by two ways  a) External heating By surrounding the melt channel with an appropriate electric heating element. b) Internal heating In the internal heating system their is an electric heating element which is kept inside the melt channel. DEMERITS OF HOT RUNNER SYSTEM Hot runner system is more complicate and expensive. Hot runner mould is more difficult to...
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