Aluminum Extrusion Troubleshooting

Hollow that tends to blow out (convex) at the center (LR)

Problem Description

A hollow profile inflates primarily at the center while outer regions remain stable, usually under high pressure or speed.

Cause–Correction Mapping
  • Corners holding back on breakthrough
    Cause in: Die

      Corrections

    • Open corners of weld chamber to increase flow to corners and streamline flow.

    • Reduce bearings at corners on die and mandrel.

  • Excess flow to profile center
    Cause in: Die

      Corrections

    • Weld restrictor bump on housing; restrict die/pre-chamber at center of port which is blowing out.

      Disadvantage: Welding may weaken die.

    • Choke cap bearings to direct/control metal flow.

      Disadvantage: Choke creates added pressure and premature washout of bearings.
  • Unequal flow
    Cause in: Die

      Corrections

    • Adjust flow by milling/grinding inadequate ports

      Advantage: Weld chamber increase may enhance weld integrity.

Please note that the information provided in this article is intended to be a general guide to the causes and corrections of Hollow that tends to blow out (convex) at the center (LR) 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.