TROUBLESHOOTING

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When molding Santoprene TPVs and our other TPE products, pressures in the mold work to increase the contact between the shot material and the mold surface. Generally, high injection pressures maintain part properties, improve part appearance and reduce molding cycle times. When the melt flow pressures do not allow for the material to pack out evenly against the mold cavity, poor surface finish can result.

Mold Fill Is Too Slow
The majority of our TPVs are shear dependent. They require fast mold filling via high injection speeds and pressure to increase shear through the system, which reduces their viscosity. If increasing injection pressure and injection speed does not remedy a poor finish, increasing the melt temperature and mold temperature will also improve surface appearance when molding our materials.

Mold Function Is Incorrect
First make sure that venting and gate size are not reducing the melt flow speed. Vents that are too small can lead to trapped air in the mold cavity, which can slow melt flow into the cavity. We do not recommend using mold releases or lubricants. Over time, the lubricants may actually cause the parts to stick in the mold due to build up and vent clogging. Be sure that the mold surface is clean. Avoid thick ribs and bosses that will create sink marks on the opposite side of the part.

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