A cooling plate assembly for an injection molding machine includes a cooling plate and a cooling fluid conduit system in the cooling plate. The cooling fluid conduit system includes a cooling fluid line extending between a cooling fluid inlet and a cooling fluid outlet. A socket is open to a front face of the cooling plate and intersects the first cooling fluid line. A cooling tube is mounted to the cooling plate, and includes a molded-article-receiving nest for receiving and cooling an injection molded article, a spigot received in the socket and blocking the first cooling fluid line, and a cooling tube conduit adjacent the molded-article-receiving nest. The cooling tube conduit extends between a cooling tube fluid inlet connected to the first cooling fluid line upstream of the socket, and a cooling tube fluid outlet connected to the first cooling fluid line downstream of the socket.