An injection molding apparatus includes an injection molding nozzle having a nozzle body defining a channel for flow of molding material and a nozzle tip coupled to the nozzle body. The nozzle tip is shaped to define a converging gap with a mold component into which the nozzle tip is inserted during use. A seal piece having a wedge or wedge-like portion is disposed between the nozzle tip and the mold component Pressure of molding material acting on a surface of the wedge portion wedges the wedge portion into the converging gap.