Injection molding apparatus for delivering multiple shots of materials to a plurality of mold cavities

An injection molding apparatus for delivering multiple shots of materials to a plurality of mold cavities, the apparatus comprising:

• a plurality of mold cavities, wherein each cavity has a nozzle fluidly communicating with the cavity for delivering multiple shots of two or more materials to the cavity, and each cavity has sensors at two locations of flow in or into the cavity;
• a drive mechanism for initiating delivery of a first shot of a first material from a single source to the nozzles for the simultaneous filling of said plurality of mold cavities;
• a controller communicating with the sensors for receiving signals from the sensors of a property that is indicative of a volume or flow of the first material in or into the corresponding cavity;
• the controller including a program that uses the received signals to estimate, during delivery of the first shot, when the mold cavity will or has reached a predetermined fill volume by calculating a flow rate or fill volume of the first material or comparing the signal or a value calculated from the signal to a target value;
• the program generating an output signal for each cavity based on the estimate to control movement of a valve pin in the nozzle of each cavity to independently stop the delivery of the first shot to each cavity;
• and
• a drive mechanism for initiating delivery of a second shot of a second material to the cavities subsequent to the step of stopping the delivering of the first shot.