Abstract: The injection of synthetic resin into the cavities of a plastic molding press is provided by a plurality of electrically driven plunger mechanisms each of which includes an elongated rotary screw connected to the output of an electric motor. The screw is threaded operatively to an elongated plunger which extends into the fixed mold and is arranged to support a pill or preform for injection into the runner leading to one or more mold cavities. The electric motor of each plunger mechanism is controlled by a computer program which is capable of varying the velocity and pressure delivery of material to the mold, as well as adjusting the temperature of the mold.