Aluminum Extrusion Troubleshooting

Angularity (Squareness)/Flatness

Problem Description

The extruded profile does not maintain proper squareness or flatness. Surfaces that should be perpendicular or planar show angular deviation or distortion.

Cause–Correction Mapping
  • Bearing squareness, flatness
    Cause in: Die

      Corrections

    • Square the bearings perpendicular to die face, flatten bearings perpendicular to metal flow.

  • Billet temperature uniformity
    Cause in: Equipment

      Corrections

    • Adjust temperature as required.

  • Bolsters, sub-bolsters
    Cause in: Equipment

      Corrections

    • Inspect, repair and/or replace tooling as needed; clean, check hardness and flatness.

      Advantage: Minimizes metal flow problems.
  • Container temperature
    Cause in: Equipment

      Corrections

    • Adjust container temperature.

  • Cracked webs/ armpits
    Cause in: Die

      Corrections

    • Replace die: If die is needed to expedite delivery, weld using proper welding techniques.

      Disadvantage: Welding is a short term solution.
  • Port openings not balanced to sectional flow requirement
    Cause in: Die

      Corrections

    • Mill/grind ports to accommodate profile section.

      Disadvantage: May weaken die possibly and short term solution.
  • Pressure ring tooling
    Cause in: Equipment

      Corrections

    • Inspect and replace pressure ring as needed; clean pressure rings and platen pressure ring cavity.
      NOTE: AVOID SHIMS

  • Unbalanced feed into flow pattern
    Cause in: Die, Profile

      Corrections

    • Flow Adjustment: Adjust port relationships to allow satisfactory balanced feed into flow pattern.

      Advantage: Increased metal flow reduces extrusion and break through pressure.

    • Adjust shape of pre-chamber in die to alter metal flow in slow area, milling preferred for equal adjustment; grinding is second best.

      Advantage: Improved die welds.
  • Unbalanced flow in weld chamber
    Cause in: Die

      Corrections

    • Mill/grind weld chambers to accommodate profile.

Please note that the information provided in this article is intended to be a general guide to the causes and corrections of Angularity (Squareness)/Flatness 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.