Method for casting a thermoplastic automotive air bag cover skin with a

Abstract

Method and apparatus including a powder box and heatable shell tool are disclosed for forming a thermoplastic automotive air bag cover skin with a lesser strength thermoplastic tear seam strip insert wherein the latter is initially formed with a protruding rib on one side and a pointed ridge on an opposite side. A heat resistant elastomeric transfer socket attached to the powder box interior receives and holds the insert rib and thereby the insert in a prescribed tear seam configuration and then positions the tear seam strip insert against a heated skin defining mold surface on the shell tool when the powder box is joined with the latter. The skin is formed by casting thermoplastic powder from the powder box against the heated mold surface and about the tear seam insert. The pointed ridge of the tear seam strip insert is pressed with a limited force against the heated mold surface by the transfer socket and prevents air entrapment between the tear seam strip insert and mold surface as the insert melts and joins with a surrounding layer of powder melt that forms the skin on cooling. In the process of melting, the pointed edge of the ridge and all of the rib of the insert melts and becomes part of a tear seam where the insert fuses with the skin while conforming to the mold surface to smoothly blend with the outer side of the skin while the backside of the insert smoothly blends with the surrounding inner side of the skin.