US Patent 7581944 Injection molding apparatus having a valve pin bushing

An injection molding apparatus, such as a hot runner or hot half, includes a manifold having a manifold channel and a nozzle having a nozzle channel. The nozzle is coupled to the manifold, and the manifold channel and the nozzle channel are in communication to define a flow channel. A valve pin bushing has a flow restrictor disposed in the flow channel on an upstream side of the valve pin bushing. A moveable valve pin extends through a bore of the valve pin bushing.