Extrusion

{
  "id": "MLC-T-ENV-010590",
  "term": "Extrusion",
  "field": "Environment",
  "definition": "1. A manufacturing process which creates articles with a fixed cross-sectional profile by pushing material through a die orifice. Commonly used to make metallic and plastic objects.\n\n2. Application of pressure to a billet of metal, forcing the metal to flow through a die orifice.\n\n3. Application of pressure to a copper workpiece, forcing the copper to flow through a die orifice.\n\n4. The types of extrusion methods are as diverse as the products that can be fabricated by extrusion. Extrusion methods include blown film, sheet extrusion, cast film, extrusion coating, profile extrusion, pipe and tubing extrusion, wire and cable coating, and fiber extrusion. In most extrusion operations, dry resin material is poured into a hopper, which directs the resin material into the feed throat of the extruding machine where the resin is heated. A large continuously revolving screw encased in a long heating chamber then carries the heated resin down the length of the screw toward a die (orifice) at the end of the chamber. The revolving screw forces the fluidized resin material through the die which has the shape of the cross section of the final plastic product. After the resin material exits the die, it may be wound into a roll, or transported on rollers or a conveyer belt where it is cooled by air or water immersion.\n\n5. Application of pressure to a billet of aluminum, forcing the aluminum to flow through a die orifice. The extrusion subcategory is based on the extrusion process.",
  "references": [
    "EPA EV-Commercial Processes-Manufacturing Processes",
    "40 CFR 471.02 (CFR 2013)",
    "40 CFR 468.02 (CFR 2013)",
    "EPA Preferred and Alternative Methods for Estimating Air Emissions from Plastic Products Manufacturing at http://www.epa.gov/ttnchie1/eiip/techreport/volume02/ii11.pdf",
    "40 CFR 467.02 (CFR 2013)"
  ],
  "url": "https://mlchart.com/terminology/environment/extrusion/"
}