Method of forming a parison having multiple resin layers

A method of forming a parison having multiple thin resin layers thereby decreasing injection molding cycle time to optimize parison production rates, comprising the steps of:

• a) injection molding a first of first parison layers on a first core rod assembly at a first parison injection molding station;
• b) providing second parison layer injection stations located on opposite sides of the first parison layer injection molding station;
• c) moving the first of the first parison layers, while supporting the first parison layer along its entire length on and cooling the first parison layer by the first core rod assembly, from the first parison layer injection molding station to one of the second parison layer injection molding stations;
• d) injection molding a second of the first parison layers at the first parison layer injection molding station on a second core rod assembly while the first of the first parison layers is on the first core rod assembly at the one of the second parison layer injection molding stations at which a second parison layer is injection molded thereon to form a first two layered parison;
• e) moving the second of the first parison layers, while supporting the second of the first parison layers along its entire length on and cooling the second of the first parison layers by the second core rod assembly, to the other of the second parison layer injection stations;
• f) injection molding a third of the first parison layers on the first core rod assembly at the first parison layer injection molding station while the second of the first parison layers is on the second core rod assembly at the other of the second parison layer injection molding stations at which a second parison layer is injection molded thereon to form a second two layered parison thereon;
• and
• g) repeating steps a) to f) to form other first parison layers and two layered parisons.