<\/a>Avoiding Warp<\/strong><\/h4>\nSink Marks<\/strong>
\nAs the plastic solidifies in the mold it freezes from the outside (near the mold surface) toward the inside. In thick sections this results in inward pulling stresses (due to contraction) that can cause sink marks in the outer surfaces of the part.<\/p>\nPart Warpage<\/strong>
\nIn addition, because thinner sections will freeze faster than thicker sections there is also the possibility of stresses building up between thick & thin sections, resulting in part warpage.<\/p>\n![\"uniform-wall-img-1\"](\"https:\/\/ulprospector.ul.com\/media\/2014\/11\/uniform-wall-img-1-300x129.jpg\")
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Avoiding warp by minimizing, the use of ramps and gussets.<\/strong>
\nWarpage due to stresses in step transitions between wall thicknesses can be improved through the use of a ramp.<\/p>\nThe use of gussets can be helpful to provide support in corners to avoid warping.<\/p>\n
A.<\/strong>\u00a0High stress concentrations
\nB.<\/strong>\u00a0Reduced stress concentrations
\nC.<\/strong>\u00a0Thinner walls result in shrinkage during cooling
\nD.<\/strong>\u00a0Gussets provide additional support to reduce warpage<\/p>\n![\"uniform-wall-img-2\"](\"https:\/\/ulprospector.ul.com\/media\/2014\/11\/uniform-wall-img-2.jpg\")
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<\/a>Avoiding Sink<\/strong><\/h4>\nThicker and non-uniform wall thicknesses can often result in sinks in the material due to the same solidification physics described above.<\/span><\/p>\nThe use of thinner, uniform wall thicknesses helps to avoid sink.\u00a0<\/span><\/p>\n
\nAs the plastic solidifies in the mold it freezes from the outside (near the mold surface) toward the inside. In thick sections this results in inward pulling stresses (due to contraction) that can cause sink marks in the outer surfaces of the part.<\/p>\n
Part Warpage<\/strong> Avoiding warp by minimizing, the use of ramps and gussets.<\/strong> The use of gussets can be helpful to provide support in corners to avoid warping.<\/p>\n A.<\/strong>\u00a0High stress concentrations Thicker and non-uniform wall thicknesses can often result in sinks in the material due to the same solidification physics described above.<\/span><\/p>\n The use of thinner, uniform wall thicknesses helps to avoid sink.\u00a0<\/span><\/p>\n
\nIn addition, because thinner sections will freeze faster than thicker sections there is also the possibility of stresses building up between thick & thin sections, resulting in part warpage.<\/p>\n<\/p>\n
\nWarpage due to stresses in step transitions between wall thicknesses can be improved through the use of a ramp.<\/p>\n
\nB.<\/strong>\u00a0Reduced stress concentrations
\nC.<\/strong>\u00a0Thinner walls result in shrinkage during cooling
\nD.<\/strong>\u00a0Gussets provide additional support to reduce warpage<\/p>\n<\/p>\n<\/a>Avoiding Sink<\/strong><\/h4>\n