Specific Process Knowledge/Back-end processing/Polymer Injection Molder: Difference between revisions
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In this type of process the mold remains at the same temperature during the entire injection molding cycle. The temperature should not exceed the glass transition (or melting point) temperature of the polymer being used. Otherwise the polymer will never get cold enough to solidify to a degree where it can be demolded without being deformed/damaged. How close one can get to the glass transition temperature depends on several factors like e.g. polymer type, cooling time and whether the polymer has a tendency to stick to the shim (especially an issue when replicating high aspect ratio structures). With Topas 5013L-10 (which has a Tg around 135°C) one can often go up to 100°C and for samples that are easy to demold even higher (110-120°C). For polymers with very low Tg (such as e.g. flexible polyurethanes) one often has to run as cold as possible. With the mold heating switched completely off and mold cooling water fully open, the lowest achievable mold temperature is around 15°C. | In this type of process the mold remains at the same temperature during the entire injection molding cycle. The temperature should not exceed the glass transition (or melting point) temperature of the polymer being used. Otherwise the polymer will never get cold enough to solidify to a degree where it can be demolded without being deformed/damaged. How close one can get to the glass transition temperature depends on several factors like e.g. polymer type, cooling time and whether the polymer has a tendency to stick to the shim (especially an issue when replicating high aspect ratio structures). With Topas 5013L-10 (which has a Tg around 135°C) one can often go up to 100°C and for samples that are easy to demold even higher (110-120°C). For polymers with very low Tg (such as e.g. flexible polyurethanes) one often has to run as cold as possible. With the mold heating switched completely off and mold cooling water fully open, the lowest achievable mold temperature is around 15°C. | ||
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