INJECTION MOLDING POWDER GREENWARE COMPOSITES WITHOUT KNIT LINES

摘要

A method and apparatus for injection molding powder suspensions is disclosed wherein an elastomeric bladder (12) is disposed within a mold cavity (20) of a mold (22). A powder suspension (46) comprising a powder and a binder system is injected into the elastomeric bladder. The injected powder suspension causes the elastomeric bladder (12) to be distended until the mold cavity is filled. The powder is a ceramic, a metal or a cermet. The binder system comprises a binder, such as methylcellulose, and a carrier such as water. Distention of the elastomeric bladder (12) applies a significant force to the powder suspension to prevent jetting and the formation of knit lines within the injected powder suspension. The bladder and the injected powder suspension are then exposed to conditions sufficient to convert the injected powder suspension to form a molded powder greenware composite. The molded powder greenware composite can then be removed from the mold for convention processing to form a finished powder part.