An injection foam molding machine of the invention includes: a movable mold platen; a fixed mold platen; a mold fastening hydraulic cylinder that is provided at each of four corners of both mold platens; a tie bar that is driven by the hydraulic cylinder to fasten the molds; two sets of mold opening and closing actuators that drive the movable mold platen to move close to or away from the fixed mold platen; two sets of dedicated core back devices; and a control device that controls the two sets of mold opening and closing actuators and the two sets of dedicated core back devices, wherein the control device includes a dedicated core back program that simultaneously controls the two sets of mold opening and closing actuators and the two sets of dedicated core back devices during a foaming core back operation of moving the movable mold platen away from the fixed mold platen.

An injection molding apparatus comprising: a pneumatically driven actuator having a piston mounted within a fluid sealed chamber for slidable axial movement along or against an interior surface of the fluid sealed chamber via a non-elastomeric engagement or with a non-elastomeric material disposed between the piston and the interior surface of the fluid sealed chamber, the piston forming first and second drive chambers within the fluid sealed chamber, each drive chamber having respective fluid flow ports, a source of pressurized gas that generates gas flow at a selected maximum pressure or flow rate, a gas metering mechanism, a controller interconnected to the gas metering mechanism, the controller controllably moving the gas metering mechanism to selectable positions that correspond to reduced pressures or reduced flow rates during the course of pin travel from the fully downstream gate closed position to the fully upstream gate open position.