A method is described for injection molding a hollow object. The method has the steps of: (i) waiting for a cycle start signal from a press, (ii) upon receiving the cycle start signal, driving an actuator in order to regulate a flow of molten material towards a mold cavity by displacing a shutter, (iii) after a certain time, or simultaneously, sending a fluid injection signal to an injection unit in order to command the latter to activate a fluid injector to inject fluid under pressure into the mold cavity; (iv) after a certain time, or simultaneously, driving the actuator in order to regulate, by displacing the shutter with positional continuity and/or according to a programmed dynamic profile, a flow of molten material that the pressurized fluid is removing from the cavity and pushing towards the press.

A method of forming a part for a vehicle. The method includes positioning a plurality of continuous fiber reinforcements within a mold cavity of a mold, filling the mold cavity including the plurality of continuous fiber reinforcements with molten resin, and injecting fluid into the mold cavity to hollow a center portion of the molten resin.