| 摘要 |
An injection mold apparatus having two halves, a core portion and a cavity portion. One or more gas injection devices, such as porous metal devices, are located in either of the two portions of the mold. Once a charge of hot melted plastic is injected into the mold cavity, gas is injected through gas injection devices forcing the hot plastic against the opposite mold half and into any recesses and grooves. Gas seals are formed by the plastic to prevent gas in the mold cavity from reaching the exterior surface of the molded part during shrinkage of the plastic. The centers of mass of the plastic at rib intersections are optimally positioned to eliminate sink marks on the external finished surfaces of the molded parts.
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