Aluminum Extrusion Troubleshooting

Blisters

Problem Description

Gas-related surface blisters appear on the extrusion.

Cause–Correction Mapping
  • Bad container seal
    Cause in: Equipment

      Corrections

    • Reface container.

  • Billet temperature too high
    Cause in: Equipment

      Corrections

    • Reduce billet temperature.

  • Die opening too large for container
    Cause in: Die

      Corrections

    • Ensure port entry is within maximum circumscribed circle on port entry chart.

  • Dirty container
    Cause in: Equipment

      Corrections

    • Use cleanout block.

  • Dummy block condition
    Cause in: Equipment

      Corrections

    • Clean, repair or replace dummy block.

  • Excessive lubrication on billet/dummy block/die
    Cause in: Equipment

      Corrections

    • Use less lubrication or employ different type/process.

  • Gas entrapment
    Cause in: Equipment

      Corrections

    • Use burp cycle or vent dummy block.

  • Improper butt shearing
    Cause in: Equipment

      Corrections

    • Repair/redesign butt shear.

  • Insufficient butt thickness
    Cause in: Equipment

      Corrections

    • Increase butt thickness.

  • Press alignment
    Cause in: Equipment

      Corrections

    • Realign press.

Please note that the information provided in this article is intended to be a general guide to the causes and corrections of Blisters in aluminum extrusion. However, it is important to note that the specific cause and correction of any particular defect will vary depending on the specific extrusion process, alloy, and other factors. Therefore, it is important to consult with an experienced and professional engineer to ensure that the correct diagnosis is made and the most suitable correction is chosen.