Pressure Controlled Venting of Structural Foam Molds
Original Publication Date: 1979-Jan-01
Included in the Prior Art Database: 2005-Feb-19
Injection under pressure of thermoplastic foam into a closed structural mold cavity requires venting of the cavity unless it has previously been evacuated. Such venting is typically accomplished by cutting shallow channels 11 (e.g., 0.1 mm X 20 mm) from the cavity to the exterior at various points around the peripheral area of the mold 10. High and low pressure areas in the cavity 12, as a function of, for example, distance from the injection orifice 13. cause uneven density in the hardened material, although higher pressure can contribute to better surface finish.