TROUBLESHOOTING

The leading causes of surface detail problems on parts molded from Santoprene TPVs are improper filling and packing conditions. 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. A reduction of pressure in the mold cavity can be caused by the gate freezing off prematurely, poor mold design, or low pack/hold pressures. Verify that the set up conditions are correct using the Start Up Procedures.

Mold Filling Improperly
If material is not filling surface details on the part, there may not be enough pressure or material to fill the part. First check that the shot size is correct. If the shot size is correct, try increasing the injection speed and back pressure. This will help ensure there is enough pressure in the mold to encourage contact between the melt flow and the mold surface.

Packing Conditions Are Improper
Under-packing of the mold cavity can lead to excessive shrinkage, shrink voids in thicker wall sections, sinks in large surface areas, and poor part appearance. Traditionally, mold fill time takes between 0.5 and 2 seconds, depending on part volume, runner-gate style and size, cavity locations, and injection pressure. Increasing the second stage pressure and time will also help to maintain pressures in the mold necessary for good surface finish.

Polymer Cooling Rate Is Too High
Increasing mold temperatures will help by reducing the cooling rate of the melt and encouraging filling of surface details.

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