a spin pack assembly for the extrusion of synthetic filaments . novel features are the polymer flow channels of the breaker plate and spinneret plate which comprise a capillary with open ends , the entrance ends of the breaker plate and spinneret plate and the exit end of the breaker plate defining , respectively , enlarged inlets and outlets , the walls of which intersect with adjacent walls to form a closed , interlocking network of ridges on the top surfaces of the breaker plate and spinneret plate and on the bottom surface of the breaker plate , so as to eliminate areas of low or zero velocity flow of polymer and to reduce pressure differences in polymer in the breaker plate - spinneret plate area .