Mandrels
“In co-molding processes, pre-formed parts are further provided within the tooling before material is injected into the tooling. In such cases, the pre-formed parts can be integrated into the component that is being formed. When a pre-formed part includes a cavity that is not to be filled with the injected material during the molding process, a mandrel may be used to occupy the cavity to prevent the material from flowing into the cavity.”
“Currently, there are various different types of mandrels that are used in molding processes, including cast ceramic mandrels, salt mandrels, low-melt alloy mandrels, trapped rubber mandrels, and machined metal mandrels. None of those mandrels, however, provide all of the properties that may be desired in a mandrel, particularly when a cavity is to be is isolated. Such properties can include, for example, sufficient rigidity during mandrel insertion, sufficient mechanical support and hydraulic sealing during the molding process, low mechanical stress during mandrel removal, and the absence of mandrel residue after mandrel removal.”
Recent US Patents
10/19/2010
7,815,839
Hybrid mandrels
Vontell, Klinetob and Feeney of United Technologies, Connecticut have developed a mandrel for partially filling a cavity during injection molding consisting of a rigid inner core and an elastomeric outer layer that at least partially surrounds the rigid inner core, wherein the elastomeric outer layer is adapted to expand during a molding process to seal a cavity to prevent incursion of material injected during the molding