What is the overflow value of plastic molds?

The overflow value, also known as the overflow well or overflow channel, is a feature in plastic molds used in injection molding. It is designed to prevent excess plastic material from escaping during the molding process.

High pressure is applied to the mold cavity as molten plastic is introduced during injection molding. The mold is typically designed with a slight gap or tolerance between the two halves of the mold, known as the mold cavity and the mold core. This gap allows for the plastic material to flow and fill the mold cavity completely.

The overflow value is a small channel or well incorporated into the mold design, usually located near the parting line or in a specific area where excess plastic can escape. When the molten plastic fills the mold cavity completely, any excess material flows into the overflow channel instead of being trapped between the mold halves or causing a flash on the final part.

The specific overflow value size or capacity can vary depending on the part and mold design. It is typically determined based on factors such as the material viscosity, injection pressure, part geometry, and desired part quality. The overflow value needs to be large enough to accommodate any excess material but not so large that it affects the structural integrity or appearance of the final part.

Designing and positioning the overflow value properly is an essential aspect of mold design to ensure successful and high-quality injection molding. Mold designers and manufacturers consider factors such as part complexity, material properties, and process conditions to determine the appropriate overflow value for a specific mold.

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