PATENT DOCUMENT

Abstract:
An injection blow molding (IBM) system and method for controlling the surface temperature of the parison molds by passing heat transfer fluid through a plurality of fluidly-coupled heat transfer channels. The heat transfer channels can be formed primarily in die sets to which the parison molds are attached. The placement and distribution of the heat transfer channels relative to the parison-forming surfaces helps control the temperatures of the bodies and necks of the parisons being formed, instead of relying on various adjustments by an IBM operator. This system/method reduces the discretion required by the IBM operator and shifts the burden of consistently making high-quality parisons and molded articles onto the designer of the IBM tooling.

Full Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    Embodiments of the present invention relate to an injection blow molding apparatus and method for forming molded articles. 
         [0003]    2. Description of the Related Art 
         [0004]    Injection blow molding (IBM) is a technique used for creating various containers such as plastic bottles for medication or other contents. The IBM process is performed with an IBM machine that first injection molds a resin into a plurality of parisons of desired shapes and then blow molds the parisons into the final molded articles. 
         [0005]    An injection station of the IBM machine typically includes a split parison mold assembly that defines a plurality of cavities within which the parisons are formed. In the injection molding stage of the IBM process, the parison-forming surfaces of the split parison mold are heated to and/or cooled to different temperatures via a plurality of water lines formed in the split parison mold near the parison-forming surfaces. The water lines may be supplied with water at different temperatures depending on the location of the water line relative to the neck or body of the parison being formed. Typically, a plurality of individual thermolators are required to control the temperature of water supplied to the various water lines in the parison mold and an operator is required to use a significant amount of discretion in making adjustments to the water temperature flowing through water lines at different locations along the body and/or neck of the parison during the injection blow molding process. 
         [0006]    The operator discretion necessary to make certain parison mold designs function properly requires highly experienced IBM operators and can require significant trial and error in order to determine satisfactory operating parameters. Further, the complexity of manufacturing and operating split parison molds with multiple water lines formed therein can result in high capital costs, high operating costs, and high maintenance costs. 
         [0007]    Thus, it would be desirable to have an injection molding system and/or process where IBM operator discretion is minimized, trial-and-error operation of the IBM operator is minimized, and mold tooling design, fabrication, replacement, and maintenance costs are minimized. 
       SUMMARY OF THE INVENTION 
       [0008]    Some embodiments of the invention disclose an injection blow molding system for injection molding a resin into a plurality of parisons and blow molding the parisons into a plurality of molded articles. The injection blow molding system includes an injection station for injection molding the resin into the parisons and a blowing station for blow molding the parisons into the molded articles. The system also includes a heat transfer fluid source and an indexing head for transferring the parisons from the injection station to the blowing station. The injection station includes a split parison mold assembly shiftable between an open position and a closed position. The split parison mold assembly includes first and second body mold halves for defining the exterior shape of the bodies of the parisons. The injection station defines one or more heat transfer channels coupled in fluid-flow communication with the heat transfer fluid source. In some embodiments of the injection station, less than 50 percent of the total volume of the heat transfer channels is defined within the body mold halves. 
         [0009]    Other various embodiments of the invention disclose an injection blow molding system for injection molding a resin into a plurality of parisons and blow molding the parisons into a plurality of molded articles. The injection blow molding system includes an injection station for injection molding the resin into the parisons and a blowing station for blow molding the parisons into the molded articles. The injection blow molding system further includes a heat transfer fluid source and an indexing head for transferring the parisons from the injection station to the blowing station. The injection station includes first and second die sets shiftable between an open position and a closed position and a split parison mold assembly coupled to the first and second die sets. The split parison mold assembly defines a plurality of parison cavities for receiving the resin when the die sets are in the closed position. The injection station defines one or more heat transfer channels coupled in fluid-flow communication with the heat transfer fluid source. At least a portion of the heat transfer channels are defined within the first and second die sets. 
         [0010]    Some embodiments of the invention disclose an injection blow molding system for injection molding a resin into a plurality of parisons and blow molding the parisons into a plurality of molded articles. The injection blow molding system includes an injection station defining one or more heat transfer channels and a heat transfer fluid source coupled in fluid-flow communication with the heat transfer channels. The injection station includes first and second die sets shiftable between an open position and a closed position and first and second mold half assemblies coupled to the first and second die sets respectively. The first and second mold half assemblies present respective first and second parison cavity surfaces that cooperatively define a plurality of parison cavities when the die sets are in the closed position. At least 50 percent of the total volume of the heat transfer channels is located in heat transfer channels that are spaced more than 1 inch from the parison cavity surfaces. 
         [0011]    Other embodiments of the invention disclose an injection blow molding process that includes a step of injection molding a resin into a plurality of parisons at an injection station. The injection molding step includes substeps of shifting a split parison mold assembly from an open position to a closed position, then injecting the resin into a plurality of parison cavities cooperatively defined by parison cavity surfaces of the split parison mold assembly when the split parison mold assembly is in the closed position. The injection molding step further includes a substep of passing a heat transfer fluid through heat transfer channels defined within the injection station. At least 50 percent of the total volume of the heat transfer channels is spaced more than 1 inch away from the parison cavity surfaces. The injection blow molding process also includes a step of transferring the parisons from the injection station to a blowing station, and a step of blow molding the parisons into molded articles at the blowing station. 
         [0012]    This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the detailed description. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. Other aspects and advantages of the present invention will be apparent from the following detailed description of the preferred embodiments and the accompanying drawing figures. 
     
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         [0013]    Embodiments of the present invention are described in detail below with reference to the attached drawing figures, wherein: 
           [0014]      FIG. 1  is a block diagram of a system for producing blow molded articles, particularly illustrating an injection blow molding apparatus and systems for supplying resin and heat transfer fluid to an injection station of the injection blow molding apparatus; 
           [0015]      FIG. 2  is a plan view of an injection blow molding apparatus, particularly illustrating the apparatus&#39;s injection station, blowing station, ejection station, and indexing head; 
           [0016]      FIG. 3A  is a side view of the injection station depicted in  FIG. 1 , particularly illustrating the injection mold die sets, split injection mold assembly, and resin manifold assembly; 
           [0017]      FIG. 3B  is a side view of the blowing station depicted in  FIG. 1 , particularly illustrating the blow mold die sets and split blow mold assembly; 
           [0018]      FIG. 3C  is a schematic side view of the ejection station depicted in  FIG. 1 , particularly illustrating the stripper plate used to remove blow molded articles from the core rods of the indexing head; 
           [0019]      FIG. 4  is an isometric view of an injection station configured in accordance with a first embodiment of the present invention, particularly illustrating the injection station in an open position with two die sets attached to a split parison mold assembly comprising monolithic neck mold halves and monolithic body mold halves forming a plurality of parison cavities; 
           [0020]      FIG. 5  is an isometric view of the injection station of  FIG. 4  in a closed position; 
           [0021]      FIG. 6  is an isometric view of the injection station of  FIG. 5  illustrating a plurality of heat transfer channels in phantom located within the die sets and the split parison mold assembly; 
           [0022]      FIG. 7  is a side view of the injection station depicted in  FIG. 5 , particularly illustrating the interaction between the heat transfer channels in the die sets and the heat transfer channels in the neck mold halves and also showing an absence of heat transfer channels in the body mold halves; 
           [0023]      FIG. 8  is a top view of the injection station of  FIG. 5  illustrating the heat transfer channels in phantom and includes arrows depicting the direction of flow of heat transfer fluid through the heat transfer channels from an inlet to an outlet thereof; 
           [0024]      FIG. 9  is a cutaway front view of the injection station depicted in  FIG. 5 , particularly illustrating the configuration of the heat transfer channels in the neck molds; 
           [0025]      FIG. 10  is a fragmentary cross-sectional view of the heat transfer channels taken along line  10 - 10  in  FIG. 7 , including arrows depicting the direction of flow of heat transfer fluid through the heat transfer channels in the die sets to the heat transfer channels in the neck mold halves; 
           [0026]      FIG. 11  is an isometric view of the upper neck mold half of  FIG. 4  illustrating the open-sided configuration of the contoured heat transfer channels, as well as the interlock seal recesses formed around the contoured channels; 
           [0027]      FIG. 12  is cross-sectional side view of the injection station taken along line  12 - 12  in  FIG. 9 ; 
           [0028]      FIG. 13  is a cross-sectional side view of the injection station taken along line  13 - 13  in  FIG. 9 ; 
           [0029]      FIG. 14  is a fragmentary, cross-sectional, enlarged side view of the neck mold halves as illustrated in  FIG. 14 , particularly illustrating how the portion of the heat transfer channel closest to the surface of the parison cavity is cooperatively defined by the neck mold halves and interlock insert halves; 
           [0030]      FIG. 15  is a fragmentary, cross-sectional, enlarged front view of one of the heat transfer channels in one of the neck mold halves, illustrating relationships between a neck-forming surface and its corresponding contoured channel; 
           [0031]      FIG. 16  is an isometric view of the injection station of  FIG. 5  and illustrates a plurality of mechanical fasteners joining the split parison mold assembly with the die sets; 
           [0032]      FIG. 17  is a side view of the injection station depicted in  FIG. 5 , particularly illustrating the mechanical fasters joining the interlock insert halves, neck mold halves, and body mold halves together and to the first and second die sets, respectively; 
           [0033]      FIG. 18  is a cutaway top view of the injection station depicted in  FIG. 16 , particularly illustrating the spacing of the mechanical fasteners extending horizontally through the interlock insert halves, neck mold halves, and body mold halves; 
           [0034]      FIG. 19  is a front view of the injection station depicted in  FIG. 16 , particularly illustrating the spacing of the mechanical fasteners extending vertically through the first or second die set and portions of the split parison mold assembly; 
           [0035]      FIG. 20  is an isometric view of an injection station configured in accordance with a second embodiment of the present invention, particularly illustrating the injection station in an open position with two die sets attached to a plurality of first or second individual mold halves, each individual mold half comprising an individual neck mold half and an individual body mold half forming one of the parison cavities; 
           [0036]      FIG. 21  is an isometric view of the injection station of  FIG. 20  in a closed position; 
           [0037]      FIG. 22  is a front view of the injection station of  FIG. 21 , particularly illustrating mechanical fasteners independently attaching each of the individual mold halves to the first or second die set; and 
           [0038]      FIG. 23  is a cross-sectional side view of the injection station of  FIG. 21 , particularly illustrating individual body mold halves and individual interlock inserts independently attached to the first or second die set. 
       
    
    
       [0039]    The drawing figures do not limit the present invention to the specific embodiments disclosed and described herein. The drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the invention. 
       DETAILED DESCRIPTION 
       [0040]    The following detailed description of the invention references the accompanying drawings that illustrate specific embodiments in which the invention can be practiced. The embodiments are intended to describe aspects of the invention in sufficient detail to enable those skilled in the art to practice the invention. Other embodiments can be utilized and changes can be made without departing from the scope of the present invention. The following detailed description is, therefore, not to be taken in a limiting sense. The scope of the present invention is defined only by the appended claims, along with the full scope of equivalents to which such claims are entitled. 
         [0041]    In this description, references to “one embodiment”, “an embodiment”, or “embodiments” mean that the feature or features being referred to are included in at least one embodiment of the technology. Separate references to “one embodiment”, “an embodiment”, or “embodiments” in this description do not necessarily refer to the same embodiment and are also not mutually exclusive unless so stated and/or except as will be readily apparent to those skilled in the art from the description. For example, a feature, structure, act, etc. described in one embodiment may also be included in other embodiments, but is not necessarily included. Thus, the present technology can include a variety of combinations and/or integrations of the embodiments described herein. 
         [0042]    An injection blow molding system  30 , as illustrated in  FIGS. 1-23 , is configured for injection molding a resin into a plurality of parisons and blow molding the parisons into a plurality of molded articles. As illustrated in  FIG. 1 , the injection blow molding system  30  may comprise: a resin source  32 , a resin feed system  34 , a heat transfer fluid source  36 , a temperature control system  38  comprising at least one temperature control unit  40 , and an injection blow molding (IBM) machine  42 . 
         [0043]    The resin source  32  may be any apparatus for producing and/or storing resin suitable for being molded and hardened into one or more molded articles. For example, the resin provided at the resin source  32  may be polyolefin resin. The resin feed system  34  may be coupled in fluid-flow communication with the resin source  32  and configured to inject resin into cavities of a mold of the IBM machine  42 , as described below. 
         [0044]    The heat transfer fluid source  36  may be any system capable of providing an amount of heat transfer fluid sufficient to supply the heat transfer fluid to desired portions of the IBM machine  42  in a desired quantity and for a desired length of time during an injection molding process. For example, the heat transfer fluid source  36  may be a water supply or a supply of any fluid of a sufficient viscosity to freely flow throughout desired portions of the IBM machine  42 . The heat transfer fluid may also have sufficient thermal characteristics to remain within a desired temperature range as it flows through the desired portions of the IBM machine  42 , as described in detail below. 
         [0045]    The temperature control system  38  may comprise one or more of the temperature control units  40  (e.g., thermolators) coupled in fluid-flow communication with the heat transfer fluid source  36  and operable to control the temperature of the heat transfer fluid within a predetermined temperature range. In some embodiments, a plurality of the temperature control systems  38  and/or a plurality of the temperature control units  40  may be provided. However, in some embodiments, only one temperature control unit  40  is used to control the temperature of heat transfer fluid injected into the IBM machine  42 . The temperature control unit  40  may provide heat transfer fluid of a substantially uniform temperature to the desired portions of the IBM machine  42 , as described in detail below. 
         [0046]    As illustrated in  FIG. 2 , the IBM machine  42  may be configured for injection blow molding a plurality of parisons and/or molded articles. The IBM machine  42  may comprise an indexing head  44 , an injection station  46 , a blowing station  48 , and an ejection station  50 . The injection blow molding process performed with the IBM machine  42  may include inserting polyolefin resin at the injection station  46  to form the parisons while simultaneously passing a heat transfer fluid through heat transfer channels defined within the injection station  46  to regulate the temperature of the injection station  46 , as described below. The injection blow molding process may then include actuating the indexing head  44  to transfer the resulting parisons from the injection station  46  to the blowing station  48  to be blow molded into molded articles. Next, the molded articles may be transferred via the indexing head  44  to the ejection station  50 , where the parisons are then ejected from the IBM machine  42 . The injection blow molding process described herein may be performed repetitively by the IBM machine  42 . For example, the method steps described herein may be repeated at least 100, 1,000, or 10,000 consecutive times. 
         [0047]    The indexing head  44  is configured for transferring the parisons from the injection station  46  to the blowing station  48  and then to the ejection station  50 . The indexing head  44  may comprise a face block  52  on one or more outward-facing sides thereof, one or more core rod retainer plates  56  attached to the face blocks  52 , and one or more core rods  54  attached to the core rod retainer plates  56 . Each of the core rods  54  may be spaced a distance apart from adjacent core rods  54  and may be shaped according to a desired interior shape of the parisons to be formed thereon. In one embodiment of the IBM machine  42 , the indexing head  44  may be configured to rotate the core rods  54  from the injection station  46  to the blowing station  48  and then to the ejection station  50  as directed by an operator or automated control devices (not shown). For example, the face blocks  52  may be arranged in a substantially triangular configuration with core rods  54  protruding from one or more sides of the triangular configuration, and the indexing head  44  may rotate approximately 120 degrees to move the core rods  54  on one side of the triangular configuration from the injection station  46  to the blowing station  48 . In some embodiments of the injection blow molding system  30 , the indexing head  44  may have core rods  54  protruding from each side, such that the injection station  46 , blowing station  48 , and ejection station  50  may each operate simultaneously on a different set of parisons or molded articles. 
         [0048]    The injection station  46  may be configured for injection molding the resin into the parisons. Specifically, the injection blow molding process may comprise injection molding a resin into a plurality of parisons at the injection station  46 . As depicted in  FIG. 1 , the injection station may be fluidly coupled with the resin source  32 , the resin feed system  34 , the heat transfer fluid source  36 , and the temperature control system  38  and/or unit  40 . The injection station  46  may comprise at least a portion of the resin feed system  34 , as illustrated in  FIG. 4 . For example, the resin feed system  34  may comprise or be fluidly coupled with an injection manifold  58  and one or more nozzles  60  positioned and configured for injecting resin into the one or more parison cavities. 
         [0049]    Referring again to  FIG. 2 , the blowing station  48  may be configured for blow molding the parisons into the molded articles and the injection blow molding process may include the steps of transferring the parisons from the injection station  46  to the blowing station  48  and then blow molding the parisons formed at the injection station  46  into molded articles at the blowing station  48 . 
         [0050]    As shown in  FIG. 3B , the blowing station  48  may comprise an upper die shoe  62 , a lower die shoe  64 , an upper mold half  66  coupled to the upper die shoe  62 , and a lower mold half  68  coupled to the lower die shoe  64 . The upper die shoe  62  and/or the lower die shoe  64  may be movable toward and away from each other, moving the blowing station  48  between an open position and a closed position. For example, the upper die shoe  62  and its corresponding upper mold half  66  may move upward and downward on a blowing station guide pin  70  fixed relative to the lower die shoe  64  and/or the lower mold half  68 . 
         [0051]    As shown in  FIGS. 2 and 3C , the ejection station  50  may comprise a stripper plate  72  or any other device configured for pushing, pulling, dumping, or otherwise stripping the parisons off of the core rods  54  once they have been blow molded. For example, once the indexing head  44  moves the molded articles from the blowing station  48  to the ejection station  50 , the stripper plate may be inserted adjacent to a top edge of the necks of the molded articles, between the necks and a center point of the indexing head  44 . Then the stripper plate  72  may be moved laterally away from the center point of the indexing head  44 , thus stripping the core rods  54  of the molded articles resting thereon. 
         [0052]    In some embodiments of the IBM machine  42  described above, a conventional indexing head  44 , blowing station  48 , and/or ejection station  50  may be used. However, the injection station  46  disclosed herein may comprise a multitude of improvements over prior art injection stations. Referring now to  FIGS. 3   a  and  4 - 7 , in various embodiments of the IBM machine  42  described herein, the injection station  46  may comprise first and second die sets  74 , 76 , a split parison mold assembly  78  comprising first and second parison mold halves  80 , 82  coupled to the first and second die sets  74 , 76  respectively, and a plurality of heat transfer channels  84  (dashed lines in  FIGS. 6 and 7 ) defined within the die sets  74 , 76  and/or the split parison mold assembly  78  for regulating a temperature of the parison forming surfaces of the split parison mold assembly  78 . The first and second parison mold halves  80 , 82  may also be referred to herein as first and second mold half assemblies. When the pair of first and second die sets  74 , 76  is shifted from an open position to a closed position, the first and second parison mold halves may cooperatively define one or more parison cavities  86 . In some embodiments of the injection station  46 , the first and/or second die sets  74 , 76  may slide along an injection station guide pin  88  when actuated between the open and closed positions. 
         [0053]    The first and second die sets  74 , 76  (also referred to herein as upper and lower die sets of the injection station  46 ) may be formed of nickel plate or other die set materials known in the art. The die sets  74 , 76  may be shiftable between the open position and the closed position, as mentioned above. The injection blow molding process may therefore include a step of shifting the first and second die sets  74 , 76  of the injection molding station  46  from the open position to the closed position and from the closed position to the open position. At least one of the die sets  74 , 76  may be configured to actuate toward and away from the other of the die sets  74 , 76 . For example, the first die set  74  may move toward and away from the second die set  76  along the injection station guide pin  88 . 
         [0054]    The first and second parison mold halves  80 , 82  of the split parison mold assembly  78  may be directly coupled to the first and second die sets  74 , 76  respectively. As used herein, the term “directly coupled” denotes connection of a first component to a second component in a manner such that at least a portion of the first and second components physically contact one another. The first parison mold half  80  may have a first parison cavity surface  90  ( FIG. 13 ) and the second parison mold half  82  may have a second parison cavity surface  92  ( FIG. 13 ). When the split parison mold assembly  78  is in the closed position, the first and second parison cavity surfaces  90 , 92  may define the one or more parison cavities  86  within which the resin is received. The resin feed system  34  may be coupled in fluid-flow communication with the parison cavities  86  and operable to inject the resin into the parison cavities  86 . 
         [0055]    The injection blow molding process may include injection molding a polyolefin resin into a plurality of parisons at the injection station  46 . This injection molding process may comprise shifting the split parison mold assembly  78  from the open position to the closed position, then introducing or injecting the resin, such as polyolefin resin, into the parison cavities  86  cooperatively defined by the first and second parison cavity surfaces  90 , 92  of the split parison mold assembly  78  when the split parison mold assembly  78  is in the closed position. The resin fills the parison cavities  86  and may remain therein until it hardens to a point at which it can at least temporarily hold its shape when the split parison mold assembly  78  is opened. Then the die sets  74 , 76  may be shifted from the closed position to the open position and the parisons may be removed from the parison mold halves  80 , 82  while the die sets  74 , 76  are in the open position. 
         [0056]    As perhaps best illustrated in  FIGS. 13 and 14 , each of the parison cavity surfaces  90 , 92  may comprise a body-forming surface  94 , 96  for defining the exterior shape of the bodies of the parisons and a neck-forming surface  98 , 100  for defining the exterior shape of the necks of the parisons when the split parison mold  78  is in the closed position. 
         [0057]    In various embodiments of the injection station  46 , the split parison mold assembly  78  may comprise first and second body mold halves  102 , 104 , first and second neck mold halves  106 , 108 , and first and second interlock insert halves  110 , 112  coupled to the first and second die sets  74 , 76  respectively. The neck-forming surfaces  98 , 100  ( FIG. 14 ) may be formed into the neck mold halves  106 , 108  and the body-forming surfaces  94 , 96  may be formed into the body mold halves  102 , 104 , respectively. 
         [0058]    In some embodiments of the injection station  46 , the body mold halves  102 , 104  are each monolithic components having a plurality of the parison body-forming surfaces  94 , 96  formed therein via a molding or milling manufacturing process. As used herein, the term “monolithic” means formed of a single body or member; not of multiple bodies or members fastened together. The monolithic body mold halves  102 , 104  may be configured such that the first body mold half  102  and the second body mold half  104  cooperatively define the exterior shape of the bodies of at least two, at least four, or at least six of the parisons. In other embodiments of the injection station  46 , as described below, the body mold halves  102 , 104  may each comprise a plurality first body mold halves  102  and a plurality of second body mold halves  104  each independently coupled to one of the die sets  74 , 76 , with each first body mold half  102  and each corresponding second body mold half  104  comprising at least one body-forming surface  94 , 96  formed therein. 
         [0059]    The first and second neck mold halves  106 , 108  can be directly coupled to the first and second die sets  74 , 76  respectively, and are disposed between the first and second body mold halves  102 , 104  and the first and second interlock inserts  110 , 112  respectively. 
         [0060]    In some embodiments of the injection station  46 , the neck mold halves  106 , 108  are each monolithic components having a plurality of the parison neck-forming surfaces  98 , 100  formed therein via a molding or milling manufacturing process. The monolithic neck mold halves  106 , 108  may be configured such that the first neck mold half  106  and the second neck mold half  108  cooperatively define the exterior shape of the necks of at least two, at least four, or at least six of the parisons. 
         [0061]    In other embodiments of the injection station  46 , as described below, the neck mold halves  106 , 108  may each comprise a plurality first neck mold halves  106  and a plurality of second neck mold halves  108  each independently coupled to one of the die sets  74 , 76 , with each first neck mold half  106  and each corresponding second neck mold half  108  comprising at least one neck-forming surface  98 , 100  formed therein. 
         [0062]    The first and second interlock inserts  110 , 112  (also referred to herein as interlock insert halves) may be directly coupled to the first and second die sets  74 , 76  respectively, adjacent to the first and second neck mold halves  106 , 108 . The first and second neck mold halves  106 , 108  may be disposed between the first and second interlock inserts  110 , 112  and the first and second body mold halves  102 , 104  respectively. The interlock insert halves  110 , 112  along with the first and second neck mold halves  106 , 108  may cooperatively form at least a portion of the heat transfer channels  84 , as later described herein. 
         [0063]    The heat transfer channels  84 , as illustrated in  FIGS. 6-10 , are formed in the die sets  74 , 76  and/the parison mold halves  80 , 82  and are configured to receive the heat transfer fluid. For example, the heat transfer channels  84  may be configured to receive heat transfer fluid from the heat transfer fluid source  36  and pass the heat transfer fluid from heat transfer channels  84  defined within the first and second die sets  74 , 76  into heat transfer channels  84  defined within the first and second parison mold halves  80 , 82  respectively. Heat transfer fluid may be passed through the plurality of heat transfer channels  84  defined within the injection station  46  to regulate the temperature of at least a portion of the parison cavity surfaces  90 , 92 . 
         [0064]    The heat transfer channels  84  may be coupled in fluid-flow communication with the heat transfer fluid source  36  and the temperature control system  38 . The temperature control system  38  may thus control the temperature of the heat transfer fluid fed into the heat transfer channels  84 . In some embodiments of the injection blow molding system  30 , there may be one or more temperature control systems  38  or temperature control units  40 , but only one of the temperature control units  40  may be associated with the injection station  46  and its heat transfer channels  84 . The injection molding process described herein may therefore further comprise passing the heat transfer fluid from a single temperature control unit  40  through all the heat transfer channels  84  defined within the injection station  46 . In some embodiments of the injection blow molding system  30 , all of the heat transfer fluid passed through the heat transfer channels  84  enters the injection station  46  at substantially the same temperature. 
         [0065]    The injection station  46  may define one or more inlets  114 , 116  for receiving the heat transfer fluid from the temperature control unit  40  and one or more outlets  118 , 120  for allowing fluid to flow out of the heat transfer channels. In some embodiments of the injection blow molding system  30 , the injection station  46  may define no more than two inlets  114 , 116  for receiving the heat transfer fluid from the temperature control unit  40  the heat transfer fluid from the temperature control unit  40  into the heat transfer channels  84 . For example, each of the first and second die sets  74 , 76  may comprise only one inlet  114 , 116 , respectively, for receiving fluid to be passed through all of the heat transfer channels  84  defined with that die set and associated parison mold half. 
         [0066]    As noted above, at least a portion of the heat transfer channels  84  may be defined within the first and second die sets  74 , 76 . Furthermore, at least a portion of the heat transfer channels  84  may be defined within the first and second parison mold halves  80 , 82 . For example, at least a portion of the heat transfer channels  84  may be defined within the first and second neck mold halves  106 , 108  of the first and second parison mold halves  80 , 82 . The heat transfer channels  84  defined within the first and second parison mold halves  80 , 82  may be connected in fluid-flow communication with at least a portion of the heat transfer fluid channels  84  defined within the first and second die sets  74 , 76 . For example, heat transfer fluid can be supplied to heat transfer channels  84  defined within the first and second parison mold halves  80 , 82  by heat transfer channels  84  defined within the first and second die sets  74 , 76  respectively. 
         [0067]    As perhaps best illustrated in  FIG. 8 , all of the heat transfer channels  84  defined within the first die set  74  may be connected in serial fluid-flow communication, and all of the heat transfer channels  84  defined within the second die set  76  may be connected in serial fluid-flow communication. As used herein, “serial fluid-flow communication” denotes the connection of multiple fluid carrying bodies or channels in a manner such that fluid flows sequentially through the multiple bodies or channels. The heat transfer channels  84  defined within each of the first and second die sets  74 , 76  may comprise a plurality of spaced-apart, substantially linear channels  122 . In some embodiments of the injection station  46 , each of the die sets may comprise a minimum of 2, 3, or 4 of the linear channels  122  and a maximum of 40, 20, or 8 of the linear channels  122 . Each of the linear channels  122  may have a length of at least 6, 12, or 16 inches and/or not more than 60, 48, or 36 inches. Furthermore, the linear channels  122  may extend substantially parallel to one another. The average lateral spacing between adjacent ones of the linear channels  122  may be at least 0.5, 0.75, 1.0, or 1.25 inches and/or not more than 8, 6, 4, or 2 inches. Furthermore, the average diameter of the linear channels  122  in the die sets  74 , 76  may be at least 0.05, 0.15, or 0.25 inches and/or not more than 3.0, 1.5, or 0.75 inches. 
         [0068]    As mentioned above, the linear channels  122  may be coupled in serial fluid-flow communication with one another. For example, one or more crossing heat transfer channels  124  may be positioned proximate one or more ends of the linear channels  122  and may provide fluid communication between adjacent ones of the linear channels  122 . For example, the linear channels  122  and the crossing channels  124  may cooperatively define heat transfer channels that snake back and forth laterally across each of the die sets  74 , 76 . For example, the heat transfer fluid may travel in a first direction through a first one of the linear channels  122 , enter a first one of the crossing channels  124  or a first portion of one of the crossing channels  124 , and then flow in a second, opposite direction through a second one of the linear channels  122 . In some embodiments of the injection station  46 , plugs  126  may be strategically placed throughout the linear channels  122  and/or the crossing channels  124 , thereby directing the flow of the heat transfer fluid, as illustrated in  FIG. 8 . Furthermore, the plugs  126  may also be placed at or into each end of the linear and crossing channels  122 , 124  to prevent heat transfer fluid from entering or exiting at any locations other than the inlets  114 , 116  and outlets  118 , 120 . 
         [0069]    At least a portion of the heat transfer channels  84  defined within the die sets  74 , 76  connect the heat transfer channels  84  defined within the parison mold halves  80 , 82  in serial fluid-flow communication with one another. As illustrated in  FIG. 10 , the parison mold halves  80 , 82  may each define at least two spaced-apart heat transfer channels, referred to herein as mold half channels  128 . The mold half channels  128  may be formed in the body mold halves  102 , 104  and/or the neck mold halves  106 , 108 , as later described herein. Specifically, the first and second die sets  74 , 76  may each comprise at least one connecting heat transfer channel or one connecting portion of one of the linear channels that provides fluid communication between the mold half channels  128 . For example, the mold half channels  128  may each have an inlet end  130  and an outlet end  132  in fluid communication with at least one of the linear channels  122  in the die sets. The linear channel  122  may have one of the plugs  126  placed therein between the inlet end  130  and the outlet end  132  of one of the mold half channels  128  to redirect the heat transfer fluid into that mold half channel  128 . The space between adjacent ones of the plugs  126  within the linear channels  122  in fluid communication with the mold half channels  128  may be referred to herein as a connecting portion or a connecting heat transfer channel  134 , because it fluidly connects the outlet end  130  of one mold half channel  128  with the inlet end  132  of another mold half channel  128 , as illustrated in  FIG. 10 . 
         [0070]    The inlet end  130  and the outlet end  132  of the mold half channels  128  may each be fluidly connected with the at least one of the linear channels  122  via extension channels  136 . In some embodiments of the injection station  46 , the extension channels  136  may extend downward from and substantially perpendicular to at least one of the linear channels  122 . 
         [0071]    In some embodiments of the injection station  46 , the total volume of the heat transfer channels  84  may be at least 10, 20, or 40 cubic inches and/or not more than 500, 250, or 100 cubic inches. Additionally, the total volume of the heat transfer channels  84  defined within the first and second die sets  74 , 76  may be at least 5, 15 or 30 cubic inches and/or not more than 400, 200, or 80 cubic inches. The total volume of the heat transfer channels  84  defined within the first and second parison mold halves  80 , 82  may be at least 1, 3, or 5 cubic inches and/or not more than 100, 50, or 20 cubic inches. The total volume of the heat transfer channels  84  defined within the first and second body mold halves  102 , 104  may be less than 30, 15, or 5 cubic inches, and the total volume of the heat transfer channels  84  defined within the first and second neck mold halves  106 , 108  may be at least 1, 3, or 5 cubic inches and/or not more than 100, 50, or 20 cubic inches. 
         [0072]    The ratio of the total volume of the heat transfer channels  84  defined within the die sets  74 , 76  to the total volume of heat transfer channels  84  defined in the split parison mold assembly  78  may be at least 1:1, 2.5:1, or 3.5:1 and/or not more than 20:1, 12:1, or 8:1. The ratio of the total volume of the heat transfer channels  84  defined within the die sets  74 , 76  to the total volume of heat transfer channels  84  defined in the body mold halves  102 , 104  may be at least 1:1. Thus, less than 50, 30, 25, 15, or 10 percent of the total volume of the heat transfer channels  84  in the injection station  46  may be defined within the body mold halves  102 , 104 . For example, in some embodiments of the injection station  46  none of the heat transfer channels  84  are defined within the body mold halves  102 , 104 . In various embodiments of the injection station  46 , at least 50, 60, or 70 percent of the total volume of the heat transfer channels  84  is located in heat transfer channels that are spaced more than 1, 3, or 5 inches from the parison cavity surfaces  90 , 92 . 
         [0073]    In some embodiments of the injection station  46 , at least 20, 30, 50, or 70 percent and/or not more than 98, 95, or 90 percent of the total volume of the heat transfer channels  84  is defined within the die sets  74 , 76 . In some embodiments of the injection station  46 , at least 2, 5, or 10 percent and/or not more than 80, 50, or 30 percent of the total volume of the heat transfer channels  84  is defined within the split parison mold assembly  78 . In some embodiments of the injection station  46 , at least 2, 5, or 10 percent and/or not more than 80, 50, or 30 percent of the total volume of the heat transfer channels  84  may be defined within the neck mold halves  106 , 108 . 
         [0074]    It may be desirable for the body-forming surfaces  94 , 96  of the parison molds  80 , 82  to stay within target temperature ranges during the injection molding process. In some embodiments of the injection station  46 , the target surface temperature of the body-forming surfaces (i.e., the target body surface temperature) may be at least 190, 200, or 205° F. and/or not more than 230, 220, or 215° F. 
         [0075]    During the injection molding, while the resin is received in the parison cavities  86 , the surface temperature of at least 70, 80, or 90 percent of the total surface area of the body-forming surfaces  94 , 96  of the split parison mold assembly  78  may be maintained at or within 20, 10, or 5° F. of the target body surface temperature. For example, a target body surface temperature may be 210° F., and during the injection molding, the temperature of at least 90 percent of the total surface area of the body-forming surfaces  94 , 96  may be maintained between 205 and 215° F. 
         [0076]    During the injection molding, the temperature of at least 70, 80, or 90 percent of the total surface area of the neck-forming surfaces  98 , 100  may be maintained within 20, 10, or 5° F. of a target neck surface temperature. For example, the temperature of at least 70, 80, or 90 percent of the total surface area of the neck-forming surfaces  98 , 100  may be maintained within a range having a minimum of 50 or 75° F. and a maximum of 150 or 175° F. In some embodiments of the injection station  46 , the target neck surface temperature may be at least 10, 25, or 50° F. less than the target body surface temperature. For example, if the target neck surface temperature is in the range of 50 to 175° F. then the target body surface temperature may be in the range of 190 to 230° F. In one example embodiment of the injection station  46 , the target body surface temperature may be 210° F., and the target neck surface temperature may be at least 25° F. less than the target body surface temperature. 
         [0077]    In some embodiments of the injection station  46 , at least 75, 90, or 100 volume percent of the heat transfer fluid introduced into the heat transfer channels  84  is introduced at an inlet temperature that is at or within 20, 10, or 5° F. of a target inlet temperature. The target inlet temperature may be at least 40, 50, or 60° F. and/or not more than 150, 100, or 90° F. The temperature of the heat transfer fluid may be controlled in a single temperature control unit  40  (e.g., thermolator) prior to introducing the heat transfer fluid into the heat transfer channels  84 . 
         [0078]    In certain embodiments, the neck mold halves  106 , 108  may be coupled to the die sets  74 , 76  independently of the body mold halves  102 , 104 . A first insulating gap  138  may be defined between at least a portion of the first body mold half  102  and the first neck mold half  106 , and a second insulating gap  140  may be defined between at least a portion of the second body mold half  104  and the second neck mold half  108 . 
         [0079]    As noted above, at least a portion of the heat transfer channels  84  may be defined within the first and second neck mold halves  106 , 108 . For example, at least some of the spaced-apart heat transfer channels or mold half channels  128  may be partially or entirely defined within the first and second neck mold halves  106 , 108 . In some embodiments of the injection station  46 , at least a portion of the heat transfer channels  84  defined within the first and second neck mold halves  106 , 108  may be spaced at least 0.05, 0.1, or 0.15 inches and/or not more than 2, 1, or 0.5 inches from the neck-forming surfaces  98 , 100 . In some embodiments of the injection station  46 , all of the heat transfer channels  84  that are spaced less than 1 inch from the first and second parison cavity surfaces  90 , 92  are defined within the neck mold halves  106 , 108 . 
         [0080]    The heat transfer channels  84  defined in the first and second neck mold halves  106 , 108  may include a plurality of contoured channels  142  associated with the neck-forming surfaces  98 , 100 . As perhaps best shown in  FIG. 15 , the curvature of the contoured channels  142  may substantially correspond to the curvature of the necks of the parisons to be formed at the injection station  46 . Specifically, the contoured heat transfer channels  142  may include an inner face  144  having a shape that substantially corresponds to the shape of the neck-forming surface  98 , 100  with which it is associated. 
         [0081]    As illustrated in  FIGS. 14 and 15 , the curvature of each of the contoured heat transfer channels  142  may be substantially concentric with the curvature of the neck of the parison with which it is associated and the neck-forming surface  98 , 100  with which it is associated. The inner face  144  of the contoured heat transfer channel  142  may have an arcuate shape. The inner face  144  of the contoured heat transfer channel  142  may also be spaced from the neck-forming surface  98 , 100  with which it is associated by a distance S (as illustrated in  FIG. 15 ), which may be at least 0.05, 0.1, or 0.15 inches and/or not more than 2, 1, or 0.5 inches. The inner face  144  of the contoured heat transfer channel  142  may have a radius of curvature r 1  that is at least 0.25, 0.5, 0.75, or 1 inch and/or not more than 5, 3, or 2. Furthermore, the inner face  144  of the contoured heat transfer channel  142  may extend through an angle θ (as illustrated in  FIG. 15 ) that is at least 90, 120, or 140 degrees and/or not more than 175 or 180 degrees. The radius of the neck-forming surface  98 , 100  is denoted by r 2  in  FIG. 15 . The length of each of the contoured channels  142  may be at least 1, 1.25, or 1.5 inches and/or not more than 10, 8, or 5 inches. 
         [0082]    At least one of the contoured channels  142  may be located between and fluidly connected to a supply channel  146  and a return channel  148 , with the supply channel  146  extending to the inlet end  130  and the return channel  148  extending to the outlet end  132  of the mold half channels  128 . The supply and return channels  146 , 148  may extend from the contoured heat transfer channel  142  in a direction that is generally away from the neck-forming surface  98 , 100  with which the contoured heat transfer channel  142  is associated. The supply and return channels  146 , 148  may be substantially linear and/or parallel with each other and connected to generally opposite ends of the contoured heat transfer channel  142 . The supply and return channels  146 , 148  may also be substantially perpendicular relative to the linear channels  122  in the die sets  74 , 76 . 
         [0083]    In some embodiments of the injection station  46 , the first and second interlock inserts  110 , 112  may be disposed adjacent the first and second neck mold halves  106 , 108  respectively, such that at least a portion of the contoured channels  142  are cooperatively defined by the interlock inserts  110 , 112  and the neck mold halves  106 , 108 , as illustrated in  FIGS. 13-14 . For example, the contoured channels  142  may be milled into a front face of the neck mold halves  106 , 108 , and then the first and second interlock inserts  110 , 112  may be attached to the front face of the first and second neck mold halves  106 , 108  respectively, thereby cooperatively forming the contoured channels  142 . 
         [0084]    An interlock seal  150  may be placed around a periphery of each of the contoured channels  142  at the front face of the neck mold halves  106 , 108 , such that the interlock seal  150  is disposed between the neck mold halves  106 , 108  and their corresponding interlock inserts  110 , 112 . The interlock seal  150  may be a gasket, sealant, or any other sealing device configured to prevent heat transfer fluid from leaking between the front face of the neck mold halves  106 , 108  and the interlock inserts  110 , 112 . 
         [0085]    As shown in  FIG. 9 , the injection station  46  may further comprise a plurality of first and second sealing members  152 , 154 . The first and second sealing members may be gaskets, sealant, or any other sealing device configured to prevent heat transfer fluid from leaking between the inlet ends  130  and outlet ends  132  of the mold half channels  128  and the extension channels  136  fluidly connecting the linear channels  122  with the mold half channels  128 . Each of the first sealing members  152  may be disposed between the first die set  74  and the first parison mold half  80  proximate a location where one of the heat transfer channels  84  of the first die set  74  connects in fluid-flow communication with one of the heat transfer channels  84  in the first parison mold half  80 . Each of the second sealing members  154  may be disposed between the second die set  76  and the second parison mold half  82  proximate a location where one of the heat transfer channels  84  in the second die set  76  connects in fluid-flow communication with one of the heat transfer channels  84  defined in the second parison mold half  82 . 
         [0086]    Each component of the split parison mold assembly  78  may be directly attached to its corresponding die set  74 , 76 . In some embodiments of the injection station  46 , various components may be independently attached to the die sets  74 , 76 . Specifically, the first and second body mold halves  102 , 104 , first and second neck mold halves  106 , 108 , and first and second interlock insert halves  110 , 112  may each be directly and independently coupled to the first or second die sets  74 , 76 , respectively. Therefore, the body mold halves  102 , 104 , neck mold halves  106 , 108 , and interlock insert halves  110 , 112  may each be independently disconnected from the die sets  74 , 76  without removing any of the other components. 
         [0087]    As illustrated in  FIGS. 16-19 , a plurality of male threaded members may couple the first and second interlock inserts, neck mold halves, and body mold halves to one another and/or to the first and second die sets, respectively. For example, the first and second monolithic neck mold halves may be directly coupled to the first and second die sets respectively, and the first and second body mold halves may be directly coupled to the first and second die sets respectively. The coupling of these components may be accomplished using a plurality of mechanical fasteners  156 . 
         [0088]    For example, in the embodiments illustrated in  FIGS. 16-19 , the mechanical fasteners  156  comprise a plurality of vertically-extending male threaded members extending through the first and second die sets  74 , 76  and into either one of the interlock insert halves  110 , 112  or one of the body mold halves  102 , 104 . In  FIGS. 16-19 , the mechanical fasteners  156  also include a plurality of horizontally-extending male threaded members extending through the first or second interlock insert halves  110 , 112 , then through the first or second neck mold halves  106 , 108 , respectively, and into the first or second body mold halves  102 , 104  respectively. 
         [0089]      FIGS. 4-19  illustrate an injection station  46  with the first and a second parison mold halves  80 , 82 , each comprising one monolithic body mold half, one monolithic neck mold half, and one monolithic interlocking insert half. However, in alternative embodiments illustrated in  FIGS. 20-23 , a plurality of first individual mold halves  158  and a plurality of second individual mold halves  160  are each independently attached to their respective die sets  74 , 76  in a spaced-apart configuration. As used herein, the term “independently coupled” denotes connection of a first component to a second component in a manner such that disconnection and removal of the first component from the second component does not require disconnection of any fasteners other than the fasteners that contact and connect both the first or second components. 
         [0090]    In this configuration, each of the first individual mold halves  158  has a corresponding one of the second individual mold halves  160  with which it cooperates to define a single one of the parison cavities  86 . In certain embodiments, each of the first individual mold halves  158  are horizontally-spaced from one another to thereby form first gaps  174  therebetween, and each of the second individual mold halves  160  are horizontally-spaced from one another to thereby form second gaps  176  therebetween. 
         [0091]    Advantageously, no horizontally-extending fasteners are used or required to couple the first individual mold halves  158  to one another or to couple the second individual mold halves  160  to one another, since they are each independently attached to their respective die sets  74 , 76 . Specifically, each of the first individual mold halves  158  may be coupled to the first die set  74  by one or more vertically-extending mounting fasteners  156 , and each of the second individual mold halves  160  may be coupled to the second die set  76  by one or more vertically-extending mounting fasteners  156 . The vertically-extending mounting fasteners may each include a male threaded portion. In this embodiment of the injection station  46 , vertically-extending mounting fasteners may be the only means used to couple the first and second individual mold halves  158 , 160  to the first and second die sets  74 , 76 , respectively. 
         [0092]    The plurality of first and second mold halves  158 , 160  may each comprise a first and second individual body mold half  162 , 164 , a first and second individual neck mold half  166 , 168 , and a first and second individual interlocking insert half  170 , 172  respectively. Specifically, the first and second body mold halves  102 , 104  may each comprise a plurality of first and second individual body mold halves  162 , 164 , each directly and independently coupled to the first or second die set  74 , 76  respectively and each configured to define at least a portion of the exterior shape of the body of only one of the parisons. Furthermore, the first and second neck mold halves  106 , 108  may each comprise a plurality of first and second individual neck mold halves  166 , 168 , each directly and independently coupled to the first or second die set  74 , 76  respectively and each configured to define at least a portion of the exterior shape of the neck of only one of the parisons. Also, the first and second interlocking insert halves  110 , 112  may each comprise a plurality of first and second individual interlocking insert halves  170 , 172  each directly and independently coupled to the first or second die set  74 , 76  respectively. The individual body mold halves  162 , 164  may each be spaced apart from one another, the individual neck mold halves  166 , 168  may each be spaced apart from one another, and/or the individual interlocking insert halves  170 , 172  may each be spaced apart from one another. 
         [0093]    Each of the first individual body mold halves  162  may have a corresponding second individual body mold half  164 , and each of the first individual neck mold halves  166  may have a corresponding second neck mold half  168 . Each pair of corresponding first and second individual body mold halves  162 , 164  may cooperatively defines the exterior shape of the body of one of the parisons, and each pair of corresponding first and second individual neck mold halves  166 , 168  may cooperatively define the exterior shape of the neck of one of the parisons. In some embodiments, the split parison mold of the injection station  46  may comprise at least two, four, or six of the first individual body mold halves  162 , 164  and at least two, four, or six of the second individual body mold halves  166 , 168 . 
         [0094]    The individual first and second neck mold halves  166 , 168  may each have one of the mold half channels  128  formed therein and in fluid-flow communication with the heat transfer channels  84  in the first or second die set  74 , 76 . For example, heat transfer fluid may flow from a first mold half channel in one individual first neck mold half to a second mold half channel in an adjacent individual first neck mold half via a connecting portion of one of the linear channels  122  or via one of the connecting heat transfer channels  134  in the first die set  74 . 
         [0095]    The injection molding process performed with the injection station  46  embodiment illustrated in  FIGS. 20-23  is identical to the process performed with embodiments having primarily monolithic components, as in  FIGS. 4-19 . For example, the injection molding process may comprise moving the split parison mold assembly  78  from the open to the closed position, with the core rods  54  disposed within the parison cavities  86 , then injecting resin into the plurality of parison cavities  86 . Simultaneously, the heat transfer fluid may be passed through the heat transfer channels  84  throughout the injection station  46 . 
         [0096]    In some alternative embodiments of the injection station  46 , at least some components of the first and second parison mold halves  80 , 82  may be monolithic while other components are comprised of a plurality of individual components. For example, the first and second body mold halves  102 , 104  may each be monolithic components while the first and second neck mold halves  106 , 108  may comprise a plurality of first individual neck mold halves  166  and a plurality of second individual neck mold halves  168 . 
         [0097]    In split parison mold configurations described above where at least some of the components of the split parison mold assembly  78  are independently coupled with the die sets  74 , 76  and are not directly coupled with each other, the IBM machine  42  may be reconfigured to produce different shapes and sizes of parisons and/or molded articles. For example, in an injection blow molding process, a first group of parisons may be injection molded at the injection station  46  using a first split parison mold assembly to define the exterior shape of the first group of parisons. The first group of parisons may then be blow molded into a first group of molded articles at the blowing station  48 . Next, at least one component of the first split parison mold assembly may be replaced with another component, thus creating a second split parison mold assembly attached to the die sets. Then a second group of parisons may be injection molded at the injection station  46  using the second split parison mold assembly to define the exterior shape of the second group of parisons. The second group of parisons may then be blow molded into a second group of molded articles at the blowing station  48 . The first and second groups of parisons may have different exterior shapes. 
         [0098]    In some embodiments, the same blowing station  48  may be used to blow mold both the first and second groups of parisons into the first and second groups of molded articles respectively. Alternatively, the step of blow molding the first group of parisons may utilize a first blow mold assembly, such as a first upper mold half and a first lower mold half, to define the external shape of the first group of molded articles. Then the injection blow molding process may further comprise replacing the first blow mold assembly or the first upper and lower mold halves, with a second blow mold assembly, such as a second upper mold half and a second lower mold half. The second blow mold assembly may have a substantially different configuration than the first blow mold assembly. The step of blow molding the second group of parisons may thus utilize the second blow mold assembly, or second upper and lower mold halves, to define the external shape of the second group of molded articles. The first and second groups of molded articles have substantially different configurations. 
         [0099]    As described above, the injection molding of the first and second groups of parisons may include passing heat transfer fluid through the heat transfer channels  84  defined within the injection station  46 . The temperature of the heat transfer fluid introduced into the injection station  46  may be substantially the same during the injection molding of the first group of parisons and the second group of parisons. 
         [0100]    This method of exchanging components of the split parison mold assembly  78  may be particularly useful in an initial design of the split parison mold and/or the blowing station  48 . For example, if the first group of molded articles exhibits at least one undesirable characteristic, the second parison mold assembly may be configured to eliminate the undesirable characteristic in the second group of molded articles. Then the second parson mold assembly may replace the first parison mold assembly on the die sets  74 , 76 . The undesirable characteristic may include excessive wall thickness, inadequate wall thickness, and/or non-uniform wall thickness. 
         [0101]    The exchangeable first and second parison mold assemblies may present respective first and second parison neck-forming surfaces for defining the external shape of the necks of the parisons in the first and second groups of parisons respectively. Furthermore, the first and second parison mold assemblies may present respective first and second parison body-forming surfaces for defining the external shape of the bodies of the parisons in the first and second groups of parisons respectively. 
         [0102]    During the injection molding of each of the first and second groups of parisons, the surface temperature of at least 70 percent of the total surface area of the first and second parison body-forming surfaces is maintain at a temperature within 20° F. of the target body surface temperature. For example, the target body surface temperature may be 210° F., or may be in any of the ranges disclosed herein for the target body surface temperature. In one embodiment, during the injection molding of each of the first and second groups of parisons, the surface temperature of at least 90 percent of the total surface area of the first and second parison body-forming surfaces may be maintained in the range of 205 to 215° F. Furthermore, during the injection molding of each of the first and second groups of parisons, the temperature of at least 90 percent of the total surface area of the parison neck-forming surfaces may be maintained between 75 and 150° F. Although the invention has been described with reference to the preferred embodiment illustrated in the attached drawing figures, it is noted that equivalents may be employed and substitutions made herein without departing from the scope of the invention as recited in the claims.