Method of resin transfer molding and components for use therewith

An injection head for ejecting a flowable substance, comprising:

• a housing including a chamber defined within at least a portion of the housing, the chamber having a supply port, a purge port, and an outlet spaced along the housing in a longitudinal direction;
• an actuator connected to the housing;
• and
• an injection spindle connected to the actuator and slidably retained within the chamber between an ejection position and a deployed position;
• and wherein the injection spindle has a diameter smaller than that of the chamber and is provided with respective larger diameter portions adjacent its two ends, with the larger diameter portions forming respective seals with walls of the chamber to enclose a space between the two larger diameter portions;
• wherein a plug is disposed within the chamber at an end of the spindle opposite that connected to the actuator;
• wherein in said ejection position, the two larger diameter portions of the spindle are positioned to connect the supply port with the outlet and seal off the purge port from both the supply port and the outlet, and wherein in said deployed position, the two larger diameter portions are positioned to connect the purge and supply ports and to cause the end of the spindle opposite the actuator and the plug to seal off and to block the outlet and an injection port such that when the injection spindle retracts from the deployed position, the plug remains in communication with the injection port to block the injection port, and wherein the injection head is removable from the injection port after the injection spindle is disposed in the deployed position such that the plug remains blocking the injection port and the end of the spindle opposite the actuator remains sealing off the outlet after the injection head is removed from the injection port.