Patent ID: 8048347

Claim:
A method for use in manufacturing an article having a surface, a skin and a core, the method comprising: closing a first mold portion upon a compressible seal disposed between the first mold portion and a second mold portion, the first and second mold portions each having a wall defining a pressurizable mold cavity, the mold cavity having a mold cavity wall, an injection port and a vent; pressurizing the mold cavity using a pressurizing gas at a first pressure greater than atmospheric pressure; injecting an injection comprising a mixture of a molten plastic and a blowing agent into the mold cavity through the injection port; generating a blowing agent gas from the blowing agent to form a plurality of gas cells within the mixture, the plurality of gas cells having an internal pressure less than the first pressure; waiting for a first period; venting the pressurizing gas through the vent for a second period, the first pressure being reduced to a second pressure that is less than the internal pressure of the gas cells in order to permit the plurality of gas cells in the injection that are adjacent to the pressurizing gas to expand; rupturing the plurality gas cells in the injection adjacent to the pressuring gas to form a plurality of ruptured gas cells; forming the skin adjacent to the mold cavity wall using the ruptured cells, the skin defining a core cavity; filling the core cavity with the mixture; solidifying the mixture; and separating the first mold portion from the second mold portion in order to release the article.