Question - corner warping in large HDPE parts

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K
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Looking for advice on reducing warping in injection molded HDPE parts, especially for components measuring 800×600 mm, where we see significant warping at the corners. Despite adjusting mold temperatures between 220-240°C  and experimenting with cooling rates, the improvements have been minimal. Maybe anyone has ideas how to optimized holding pressures or specific cooling times? Also, are there particular mold design modifications or additives known to help maintain dimensional stability during cooling cycles lasting 30-45 sec? Thanks in advance!

Solved by David M.

Hi, to give the most effective advice, of course, it’s better to analyze your particular part’s design and conditions applied. However, general advice would be optimizing mold design to ensure uniform mold temperature and strategic placement of gates and ejection pins. Adjust processing parameters like injection pressure, packing pressure, and cooling times to ensure even filling and cooling. Ideally better to enhance the cooling system by placing cooling channels to promote even cooling, particularly near the edges and thicker sections. Consider introducing additives such as fillers to enhance dimensional stability.

Utilize simulation tools like Moldflow to predict and address warping issues. Consider using sequential valve gating for precise control over the plastic flow, reducing internal stresses. Also ensure the ejector system is balanced to prevent deformation during part ejection, which might involve repositioning or adding more ejector pins.

    • K

      Looking for advice on reducing warping in injection molded HDPE parts, especially for components measuring 800×600 mm, where we see significant warping at the corners. Despite adjusting mold temperatures between 220-240°C  and experimenting with cooling rates, the improvements have been minimal. Maybe anyone has ideas how to optimized holding pressures or specific cooling times? Also, are there particular mold design modifications or additives known to help maintain dimensional stability during cooling cycles lasting 30-45 sec? Thanks in advance!

      0
    • D

      Hi, to give the most effective advice, of course, it’s better to analyze your particular part’s design and conditions applied. However, general advice would be optimizing mold design to ensure uniform mold temperature and strategic placement of gates and ejection pins. Adjust processing parameters like injection pressure, packing pressure, and cooling times to ensure even filling and cooling. Ideally better to enhance the cooling system by placing cooling channels to promote even cooling, particularly near the edges and thicker sections. Consider introducing additives such as fillers to enhance dimensional stability.

      Utilize simulation tools like Moldflow to predict and address warping issues. Consider using sequential valve gating for precise control over the plastic flow, reducing internal stresses. Also ensure the ejector system is balanced to prevent deformation during part ejection, which might involve repositioning or adding more ejector pins.

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Question – corner warping in large HDPE parts
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