PATENT DOCUMENT

Abstract:
A mold of the present invention is capable of modular configuration and reconfiguration for producing molded objects. Many of the same mold components are reusable in the mold to increase the flexibility of the mold and reduce expense associated with molding.

Full Description:
BACKGROUND OF THE INVENTION 
   This invention relates generally to molding, and more particularly to a modular mold for use in the manufacture and sale of molded objects. 
   The present invention has particular, but not exclusive, application in the field of molding, which is responsible for the production of many objects and components in numerous consumer and manufacturing markets. One particular application is for plastic injection molding, although other types of molding and casting fall within the scope of the present invention. Plastic injection molding machines have a fixture which receives a mold composed of two or more mold members or plates which are moved by the machine between open and closed positions. The mold members each contain mold cavities of unique geometric shapes, which partially define the shape of the molded objects produced by the mold. In the closed position, the mold plates come together, registering opposing mold cavities and defining one or more enclosed volumes having the shape of the object or component to be produced. The mold plates are secured in the closed position by the molding machine with sufficient force to remain sealed while resisting the expansive force of the mold material during charging of the mold. Liquefied molding material (e.g., plastic) is injected under pressure through a series of runner channels and a port into the enclosed volume, typically filling the available space in the volume. Thermal energy is removed so that the molding material solidifies within the enclosed volume. The mold plates are moved to the open position by the injection molding machine, and the molded object remains with one of the mold plates. An ejector device including ejection pins pushes the object and attached runners (formed by molding material in the runner channels) out of the one mold plate and the machine is ready to cycle again for the production of the next object. Molded objects are separated from runners either during ejection, or during a secondary, post molding operation, with degating being a commonly accepted term for this separation process. In instances of concurrent molding of multiple different objects, a sorting operation is also employed. 
   Plastic injection molding has enjoyed enormous commercial success because of its ability to produce large numbers of objects and components quickly and at low prices. Indeed, plastic injection molding may be the most prevalent method for the production of plastic objects. However, plastic injection molding has some drawbacks which limit its usefulness and can operate to prevent the introduction of certain types of products into the marketplace because of certain barriers to entry presented by plastic injection molding. More particularly, the mold which is used in the plastic injection molding machine is very costly to manufacture and maintain, requiring skilled artisans to produce and maintain. The cost savings previously mentioned are recognized only when a very great number of objects are manufactured. For products that will be sold in smaller numbers, or products which will be sold in numbers which are uncertain because of the uncertainty of commercial acceptance of the product, the cost of the mold is a large impediment to their production. The purchaser of molded parts is also faced with the dilemma of whether to spend the additional money to produce molds which are more efficient, i.e., as by having numerous cavities in a single mold for simultaneous production of many objects (parallel processing), or run the risk that if the product is needed in higher quantities than originally anticipated, an entirely new mold (or molds) will have to be purchased. This problem arises because the mold selected by the purchaser is strictly dedicated to production of one object (or group of objects) at one level of efficiency. Once constructed, the mold has essentially no flexibility in operation. 
   It is known that to reduce the financial risk associated with acquisition of an efficient production mold, it is possible to first produce, in a comparatively short time of fabrication, an inefficient, but low cost bridge mold, also known as a prototype mold. The bridge mold is capable of producing a small quantity of molded objects, and thus permit testing of the physical design, as well as market appeal of a molded object prior to committing to the typically larger financial investment and longer fabrication time associated with more efficient production molds. If molded objects produced by a bridge mold are found to be acceptable, the bridge mold may also be utilized to produce limited production quantities of molded objects, bridging the span of time required to fabricate an efficient production mold, and thus permit faster market availability of the molded objects than would be possible if only the final production mold were used for production. 
   In some instances, bridge molds may be produced by the same highly skilled artisan mold makers who are also employed to make production molds. The artisan mold makers use techniques for making the bridge molds that are similar to those used to fabricate production molds. In these instances of bridge mold fabrication, advantages of speed and economy are realized by compromising attributes of production molds. Such compromises typically include substitution of softer, more easily workable materials such as aluminum, as opposed to harder tool steel. Moreover, additive protective surface coatings for mold and cavity construction are not employed. Furthermore, the total number of mold cavities is typically limited to one for each object to be molded. And typically more primitive, less efficient methods of ejection, thermal regulation, degating and sorting are employed than utilized on production molds. However, even with these previously mentioned fabrication compromises, artisan mold makers are often able to produce complex molded objects which are nearly identical in shape, appearance and mechanical properties to those which will be produced by the final production mold. 
   Bridge molds produced by artisan mold makers have a number of disadvantages. For one, the cost and time required to fabricate a bridge mold is additive to the cost and time to fabricate the final efficient production mold. Therefore, molding projects utilizing bridge molding processes have higher total mold fabrication costs than molding projects that utilize only production molds. Furthermore, utilization of bridge molds extends the overall time of a molding project, as bridge molds are constructed as a first step, then following analysis and approval of the bridge mold produced prototype-molded objects, fabrication of a production mold may be commenced. While the costs of a bridge mold may be substantially less than a production mold, bridge molds fabricated by artisan mold makers are still quite expensive, owing to the typically high wages earned by artisan mold makers, and to the overall difficulty of hand crafting custom molds, even when employing the various shortcuts previously mentioned. 
   As an alternative to utilization of artisan mold makers to fabricate bridge molds in the traditional manner, several known systematic methods of mold design and fabrication may be used for the fabrication of bridge molds. In many instances these systematic mold fabrication methods may enable the fabrication of bridge molds faster and more economically than bridge molds fabricated by artisan mold makers. While being faster and less costly to fabricate, molds of these systematic processes contain all of the disadvantages of artisan-fabricated bridge molds. In addition to the disadvantages of the artisan fabricated molds, system constraints found in these systematic methods further limit molded object properties such as surface finish, part geometry and dimensional tolerances, and therefore often lack the capability to meet object design specifications. 
   Bridge molds, whether fabricated by artisan mold makers or by systematic processes, are subject to additional disadvantages which limit their usefulness. More particularly, these additional disadvantages are found when a bridge mold is utilized to meet interim production requirements, fulfilling market demands while a more efficient production mold is fabricated to replace the bridge mold. One of these disadvantages is that objects produced by an inefficient bridge mold have significantly greater per object production costs, which may offset and erode any profits realized by the earlier market entry facilitated by the bridge mold. Furthermore, the efficiency limitations of a bridge mold are also overall production capacity limitations. If the market success, and subsequent production demands of a molded object exceed the production capacity of the bridge mold, customer orders will go unfulfilled, which may result in customer dissatisfaction, and ultimately difficulty in retaining customers until greater production capacity is provided with the completed fabrication of a production mold. Being of temporary construction, bridge molds are also particularly susceptible to the effects of wear and damage, and as a result typically have short and unpredictable life spans, making them unreliable for production molding, even on an interim basis, as the bridge mold may fail before a production mold is fabricated. The cost risks associated with insufficient production capacity and unreliability of a bridge mold are magnified when the molded objects produced by the mold are a unique component part of product containing many parts. The delivery failure of the one unique part will interrupt the delivery of the entire dependant product, and may result in lost sales of much greater scale than the costs of the individual molded object. 
   Production molds may be designed to provide different levels of capacity and production efficiency, but these differing levels of capacity and efficiency have associated costs, which typically increase as the level of capacity and efficiency of the mold design is increased. Therefore, design and investment decisions of production molds require an assessment of the total molded object production requirements in order to select the most appropriate level of capacity and efficiency. As previously mentioned, fabrication of bridge molds prior to the design and fabrication of production molds enables a limited assessment of potential market acceptance and demand for molded objects. While production predictions based on market assessments from these bridge molded objects are useful, their accuracy and reliability are limited, as any prediction of future events is speculative. Furthermore, market demand for a particular molded object tends to change throughout the life cycle of the object, typically first growing as the market adopts the object, then declining as its life matures. Therefore, even if an accurate prediction of the overall demand for molded objects were possible, such predictions would still be inaccurate during various segments of the object&#39;s life cycle, and as such it is essentially impossible to make a single mold design and investment decision that is optimal for all phases of the molded objects life cycle. 
   What is needed is a modular mold and modular method of molding capable of providing rapid and economical fabrication of bridge molds that can then be rapidly and economically upgraded and transformed into an efficient production mold, and also capable of meeting variable capacity and efficiency levels. 
   It is known to provide some additional flexibility in mold making by constructing a mold which is modular. Instead of mold plates that are each monolithic, the plates are formed as frames which are capable of receiving several mold inserts. The mold inserts contain the mold cavities which mate with the mold cavities of corresponding mold inserts to define the mold volumes in the shape of the object or objects to be produced. The mold so configured may produce many of the same object or produce several different objects in a single mold cycle. Using a modular approach, much less material is required to form a mold insert than would ordinarily be required to form the entire mold plate with a cavity. The frame is generic and can receive different arrangements of mold inserts, and so the overall cost of producing a mold can be reduced. However, it is believed that the full potential of modular molds has not been exploited because of marketing methods which are still focused on single use molds. 
   Morever, modular molds suffer to a greater degree from a problem which is generally present in plastic injection molding. Although generally considered being an efficient manufacturing process, one of the primary impediments to molding efficiency is the time in which the mold is at rest after the plastic is injected into the mold, waiting for the plastic to solidify. The solidification time is a function of the heat transfer rate out of the mold volume after hot molding material is injected into the mold. The use of mold inserts may exacerbate this problem because there is insufficient contact with adjacent components of the mold to produce the most ideal conductive heat transfer. As a result, the cycle time of the injection molding machine may be increased with a modular mold. Some attempts to resolve this problem have been made, such as by having the mold insert contain its own liquid coolant circulation loop connected to the coolant system of the injection molding machine. However, this requires that the mold insert be larger, increasing its costs and reducing its flexibility of positioning within the mold plate. The fluid connections to the mold insert required every time the mold is reconfigured are complex and a source of manufacturing delay, and mold configurations and designs are limited by the need to provide for such fluid connections. Still further, steel, the common material used in mold manufacture, does not have the most ideal heat transfer characteristics. In addition to transferring heat out of the mold at a lower rate, the heat transfer is not uniform, so that there may be hot and cold spots in the mold. It is known to use aluminum, which has better heat transfer characteristics, but aluminum is less resistant to wear and subject to greater thermal expansion and contraction within the mold. 
   Another issue associated with existing injection molding molds and process relates to the reconditioning of molds. Over time, the molds (regardless of the type of material from which they are made) will wear to the point that reconditioning is required. Conventionally, skilled craftsmen are employed to perform this task. Reconditioning involves cutting down the mold to remove damage or wear, following by reforming of the cavity and runner channels leading to the cavity. The reconditioning causes the height of the mold to change, which can be particularly problematic if attempted for modular molds where the height and location of the upper surface of the mold inserts must remain the same for all mold cavities to seal. 
   Still further, the modularity of the mold inserts is limited by the modularity of the runner channels delivering liquefied molding material to the inserts. Conventionally, the runner channels have been as dedicated to a single use as the molds themselves. Providing a modular mold using mold inserts still requires that the liquefied molding material be delivered in some manner to the mold inserts. Presently, these runner channels are dedicated to a particular mold insert, making it difficult to reconfigure the mold. Mold inserts conventionally must be made of the same material so that they have the same thermal expansion in use. Even if made of the same material, mold inserts are more difficult than one piece molds to register with mating mold inserts to form a sealed mold enclosure volume because of problems with accurately positioning removable mold inserts in the mold frame. 
   SUMMARY OF THE INVENTION 
   In one aspect of the present invention, a mold member cooperable with at least one other mold member is used for forming a mold capable of receiving fluidized material into the mold for molding objects from said fluidized material. The mold member generally comprises a plate defining a submold receptacle therein. At least some submolds have cavities formed therein for receiving fluidized material to mold at least a portion of an object. At least one partition selectively mountable on the plate in the submold receptacle defines, in combination with the plate, submold receptacle sections into which respective submolds are capable of being received. The partition has a thermal transfer system for use in exchanging thermal energy with at least one of the submolds in the submold receptacle. 
   In another aspect of the present invention, a mold member having a plate and submolds generally as described in the preceding paragraph. The mold member further includes partitions selectively mountable on the plate in the submold receptacle for defining, in combination with the plate, submold receptacle sections into which respective submolds are capable of being received. The partitions are adapted for mounting on the plate so as to define arrangements of sections that have different numbers of sections in two nonparallel directions in the submold receptacle. 
   In a further aspect of the present invention, a mold member generally comprises a plate defining a submold receptacle therein. The plate has an internal heat transfer system for transporting thermal energy between the plate and a location outside the mold. At least some submolds have cavities formed therein for receiving fluidized material to mold at least a portion of an object. The submolds are receivable in the submold receptacle of the plate. At least one heat transfer member disposed generally in the submold receptacle has an internal heat transfer system therein for transporting thermal energy between the heat transfer member and a location outside the mold. At least one of the submolds as received in the submold receptacle has adjacent sides engaging the plate and the heat transfer member, respectively, such that thermal energy may be transferred between both adjacent sides of the submold and the internal heat transfer systems of the plate and heat transfer member. 
   In yet another aspect of the present invention, a mold member generally comprises a mold plate defining a submold receptacle therein, and a base plate connected to the mold plate. At least some submolds have cavities formed therein for receiving fluidized material to mold at least a portion of an object. The submolds are receivable in the submold receptacle of the plate. Support members adapted for reception in the submold receptacle each define along one edge margin thereof a support ledge disposed for engaging and supporting an edge margin of one of the submolds as received in the submold receptacle. 
   Other objects and features of the present invention will be in part apparent and in part pointed out hereinafter. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a schematic perspective of a plastic injection molding machine including a modular mold of the present invention; 
       FIG. 1A  is an enlarged, fragmentary perspective of the mold machine and modular mold of  FIG. 1 ; 
       FIG. 2  is a perspective of the modular mold including first (ejection side) and second (static side) mold members shown apart from each other; 
       FIG. 3  is the perspective of  FIG. 2 , but with submolds of the mold removed; 
       FIG. 4  is an exploded perspective of the ejection side mold member of  FIG. 3 ; 
       FIG. 4A  is a section of a mold plate of the ejection side mold member taken in the plane including line  4 A— 4 A of  FIG. 4 ; 
       FIG. 5  is an exploded perspective of the static side mold member of  FIG. 3 ; 
       FIG. 6  is a perspective of the ejection side mold member of  FIG. 3  with partitions exploded from the ejection side mold member; 
       FIG. 7  is a perspective of the static side mold member of  FIG. 3  with partitions exploded from the static side mold member; 
       FIG. 8  is an elevation of a primary partition; 
       FIG. 8A  is an elevation of a secondary partition; 
       FIG. 9  is a top plan of the primary partition of  FIG. 8 ; 
       FIG. 9A  is a top plan of the secondary partition of  FIG. 8A ; 
       FIG. 10  is a section taken in the plane including line  10 — 10  of  FIG. 9 ; 
       FIG. 10A  is a section taken in the plane including line  10 A— 10 A of  FIG. 9A ; 
       FIG. 11  is an exploded perspective of a primary partition; 
       FIG. 12  is a perspective of the ejection side mold member having a different modular configuration of submolds; 
       FIG. 13  is a perspective of the ejection side mold member having still another modular configuration of submolds; 
       FIG. 14  is a perspective of the ejection side and static side mold members shown apart from each other and submolds including multiple mold components exploded from respective mold members; 
       FIG. 15  is a partially exploded perspective of a submold of the submolds shown in  FIG. 14  associated with the ejection side mold member; 
       FIG. 16  is a portion of the submold of  FIG. 15  showing submold components exploded from the frame; 
       FIG. 17  is a perspective of a submold illustrating in phantom a portion of the submold cut away to a predetermined depth increment for subtractive reconditioning the submold and showing in phantom the predetermined depth for the next reconditioning of the submold; 
       FIG. 18  is an exploded perspective of the submold of  FIG. 17  seen from the underside and showing spacers used with the reconditioned submold; 
       FIG. 19  is a perspective of a series of the spacers; 
       FIG. 20  is a perspective of an ejection side, variable height submold of another embodiment, partially exploded and next to a mating static side submold; 
       FIG. 21  is an exploded perspective of the ejection side submold of  FIG. 20 ; 
       FIG. 22  is a perspective of an ejection side submold of a height different from the submold of  FIG. 20 ; 
       FIG. 23  is a perspective of an ejection side submold of a different height than the submolds of  FIGS. 20 and 22 ; 
       FIG. 24  is an exploded perspective of a different version of a variable height submold. 
   

   Corresponding reference characters indicate corresponding parts throughout the several views of the drawings. 
   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Referring now to the drawings, and in particular to  FIGS. 1 and 1A , a plastic injection molding machine  1  including a modular mold  3  of the present invention is shown (the reference numbers designating their subjects generally). It will be understood that the present invention also has application to other types of molding besides injection molding. The plastic injection molding machine  1  includes a first or “ejection side” machine element (generally indicated at  5 ) having a movable platen  7  and a second or “static side” machine element (generally indicated at  9 ) having a fixed platen  11 . The mold  3  includes a first or “ejection side” mold member (generally indicated at  13 ) releasably mounted on the movable platen  7  of the ejection side machine element  5 , and a second or “static side” mold member (generally indicated at  15 ) releasably mounted on the fixed platen  11  of the static side machine element  9 . The ejection side machine element  5  includes a force ejection mechanism (not shown) that actuates the ejection side mold member  13  to eject molded objects from the mold  3 . The mounting of the mold members  13 ,  15  could be reversed without departing from the scope of the present invention. 
   The movable platen  7  moves relative to the fixed platen  11  to move the ejection side mold member  13  into engagement with the static side mold member  15  for molding objects, and moves away from the fixed platen to separate the ejection side mold member from the static side mold member to allow molded objects to be ejected from the ejection side mold member. The movable platen  7  and ejection side mold member  13  are urged against the fixed platen  11  and static side mold member  15  with great force so that the mold members experience large pressures at their interface. As is known, the reason for the large forces and pressure is to hold the mold members  13 ,  15  in tight, sealing relation as plastic molding material is injected under high pressures into the mold members. The molding material may be other than plastic (e.g., a powdered metal), and may be gravity fed or otherwise delivered to the mold within the scope of the present invention. 
   Plastic injection molding (and other forms of molding and casting) can be used to make complete parts, or components of larger products. The term “object,” as used herein, is intended to refer to either complete parts or components which are assembled in a different manufacturing step(s) into the complete parts. It will be appreciated that in  FIGS. 1 and 1A , the movable platen  7  is shown spaced from the fixed platen  11  a much greater distance than it would be in operation of the injection molding machine  1  so that the mold members may be better seen. Four guide rails  17  (only three may be seen in the drawings) connect the fixed and movable platens  7 ,  11  and guide the movement of the movable platen relative to the fixed platen. The static side machine element  9  mounts a liquefied plastic injection device  19  which melts a solid plastic source (not shown) and injects under pressure a predetermined quantity of the liquid molding material into the mold  3  after the movable platen  7  moves to close the mold members of the mold. 
   The injection molding machine  1  includes a cooling system  20  for circulating a cooling liquid to the mold members  13 ,  15  for use in cooling the injected plastic in the mold members. The cooling system includes a source of cooling liquid (e.g., water), a heat exchanger to remove heat from the cooling liquid and a pump to circulate the cooling liquid (not shown). The cooling system  20  further includes a feed manifold  21  and a return manifold  22  for distributing cooling liquid to the mold members  13 ,  15 . Hoses  23  extend from the manifolds  21 ,  22  to the mold members  13 ,  15  to deliver the cooling liquid to the mold members and return heated cooling liquid from the mold members, as will be described in more detail below. Other hoses  23  extend from the manifolds  21 ,  22  to the cooling system  20  that continuously provides the cooling liquid (e.g., water).  FIGS. 1 and 1A  show only a few hoses  23  extending from the manifolds  21 ,  22  to the ejection side mold member  13  and static side mold member  15  for the sake of clarity of illustration. In actual operation, there would be many more hoses  23  extending to the static side mold member  15  and also hoses extending to the ejection side mold member  13 . The construction and operation of the injection molding machine  1  including the liquid cooling system  20  are well known to those of ordinary skill in the art, and accordingly only a general description of the construction and operation is given here. 
   In some molding operations heat or “thermal energy” may be applied to the mold instead of removed. For instance, thermosetting molding material is introduced into the mold at room temperature or below. Heat is transferred to the mold to initiate the thermosetting reaction. Heat may be applied by fluid, but most commonly is applied through electrical resistance heating (e.g., embedded heating rods). Although the embodiments described herein relate to injection molding and cooling, the present invention has application to situations where heat is added to rather than removed form the mold. Broadly speaking, the present invention makes provision for transfer of thermal energy between the mold and an exterior heat transfer system. 
   The ejection side and static side mold members  13 ,  15  are shown in additional detail in  FIGS. 2–5 . In the illustrated embodiment, the ejection side mold member  13  has four submolds (designated generally at  27 ,  29 ,  31  and  33 , respectively) containing cavities ( 27 A,  27 B,  29 A– 29 G,  31 A and  33 A) shaped for molding respective objects. The objects in the illustrated embodiment are components and accessories for geomatics equipment supports, but the type of object being molded is not critical to the present invention. The ejection side mold member  13  comprises an ejector housing  35  (broadly, “a base plate”), a support plate  37  and a mold plate  39  (see  FIGS. 2 and 4 ). The ejector housing  35  has a generally channel shape including opposite side walls  41 , and houses a first ejector device indicated generally at  43 . The space between the side walls  41  allows for movement of the first ejector device  43 . Longitudinally extending grooves  42  near the back of the ejector housing  35  on both sides receive respective clamps (not shown) associated with the movable platen  7  that releasably fix the ejection side mold member  13  to the movable platen. Eight bolts  44  (only six may be seen in  FIG. 4 ) extend through the ejector housing  35  and support plate  37 , and thread into the mold plate  39  to secure the entire ejection side mold member  13  together. 
   The first ejector device  43  includes an ejector bar plate  45  received between the side walls  41  of the ejector housing  35  and a pin retainer plate  47  resting on the ejector bar plate. The ejector bar plate  45  and pin retainer plate  47  are joined together by fasteners  49 . The ejector bar plate  45  and pin retainer plate  47  have aligned openings which slidably receive respective ones of four guide pins  51  (only three are shown) that extend from the ejector housing  35 , through four guide bushings  53  (only three are shown) received in the aligned openings, and to the support plate  37 . The guide pins  51  guide movement of the ejector bar plate  45  and pin retainer plate  47 . Ordinarily, the pin retainer plate would retain ejection pins (not shown) for use in ejecting plastic molded objects from the ejection side mold member  13 . However as will be described, the first ejector device  43  is used according to the present invention to actuate other ejector devices associated with the submolds  27 ,  29 ,  31 ,  33  of the ejection side mold member  13 . 
   Movement of the ejector bar plate  45  and pin retainer plate  47  relative to the ejector housing  35 , support plate  37  and mold plate  39  to eject objects is obtained by the aforementioned force ejection mechanism (not shown) of the ejection side machine element  5 . The force ejection mechanism includes a driven ejector bar which extends through the movable platen  7  and ejector housing  35  into connection with the ejector bar plate  45 . The ejector bar can be extended and retracted to drive operation of the first ejector device  43 . The force ejection mechanism is conventional and will not be further described herein. Return pins  57  rest against the ejector bar plate  45  and extend through holes in the pin retainer plate  47 , holes in the support plate  37  and holes in the mold plate  39 . The heads of the return pins  57  are received in counterbores (not shown) in the back side of the pin retainer plate  47  so that they do not interfere with the flush engagement of the pin retainer plate and ejector bar plate  45 . When the ejector bar plate and pin retainer plate  47  are moved toward the support plate  37  (i.e., to actuate ejection of objects), the return pins  57  project outward from a mold face  63  of the mold plate  39 . When the ejector bar plate  45  is fully seated against the ejector housing  35  (e.g., as shown in  FIG. 2 ), the ends of the return pins  57  are flush with the mold face  63  of the mold plate  39 . 
   The return pins  57  make certain that the ejector bar plate  45  is fully retracted when the mold members  13 ,  15  are closed. If the return pins  57  project out from the mold face  63  of the mold plate  39  of the ejection side mold member  13  (i.e., because the ejector bar plate  45  is not fully retracted), they engage a mold face  65  of the static side mold member  15  which pushes the return pins back to flush with the mold face  63  of the ejection side mold member mold plate  39  and completely retracts the ejector bar plate. Failure to fully retract the ejector bar plate  45  could cause ejection pins (not shown in  FIGS. 2–5 ) to protrude into mold cavities  27 A,  27 B,  29 A– 29 G,  31 A,  33 A during molding, which would cause the molding operation to fail, or at the least damage to the object being molded. 
   As assembled, the support plate  37  of the ejection side mold member  13  lies directly on the forward faces of the ejector housing side walls  41 , transmitting force directly to the ejector housing  35 . The support plate  37  has a large central opening  69  that provides access of other ejector devices (to be described) to the first ejector device  43 . The support plate  37  is formed with ledges  71  around the periphery of the central opening  69  for engaging and supporting submolds  27 ,  29 ,  31 ,  33  and other structure of the ejection side mold member  13  requiring support. The submolds  27 ,  29 ,  31 ,  33  are subject to high loads when the mold members  13 ,  15  are closed in order to maintain a seal between the mold members when the molding material is injected at high pressure. If the mold members  13 ,  15  are not adequately supported, they tend to be pushed back into the ejection side mold member  13 , causing a sealing failure. An eyebolt  73  secured to the support plate  37  is used for raising and lowering the ejection side mold member  13  to attach the mold member to the movable platen  7  of the plastic injection molding machine  1 , and for removing it from the machine. 
   The mold plate  39  receives the submolds  27 ,  29 ,  31 ,  33  in a center opening or submold receptacle  77  of the mold plate. The submolds are not illustrated in  FIG. 4 . In the assembled ejection side mold member  13 , the mold plate  39  rests directly on the support plate  37  so that loads experienced by the mold plate are transferred to the ejector housing  35  mounted on the movable platen  7  of the plastic injection molding machine  1 . The mold plate  39  is constructed with features to facilitate registration of the ejection side and static side mold members  13 ,  15  in use. Leader pin bushings  79  fixed in the mold plate  39 , and parting line lock cups  81  mounted in the mold plate by cap screws  83  receive structure associated with the static side mold member  15  (described more fully hereinafter) to achieve course and fine registration during the molding operation. 
   Two openings  85  located generally in the middle of each of the four sides of the mold plate  39  permit connection (as described hereinafter) to parts of the ejection side mold member  13  located in the submold receptacle  77  to the hoses  23  associated with the cooling system  20 . Additional openings  87  on the laterally opposite sides of the mold plate  39  provide for connection of the hoses  23  to internal cooling passages  88  located in the mold plate  39  ( FIG. 4A ). Each of the four cooling passages  88  extend from one opening  87  in the side of the mold plate  39  in a loop back to the adjacent opening  87 . Thus, cooling liquid from the cooling system  20  enters the passage  88  via a connection of hose  23  to the mold plate at opening  87 , circulates through the passage, and exits the mold plate via another hose  23  connected to the adjacent opening  87 . In this way, heat is removed from the mold plate  39  by the cooling system  20 . 
   Referring now to  FIGS. 2 and 5 , it may be seen that the static side mold member  15  comprises a clamp plate  89  secured by eight bolts  91  (only some of which are shown) to a mold plate  93 . The clamp plate  89  is attached to the fixed platen  11  of the static side machine element  9  of the plastic injection molding machine  1 . The mold plate has a submold receptacle  95  which receives submolds (generally indicated at  97 ,  99 ,  101  and  103 ), which correspond to submolds  27 ,  29 ,  31  and  33 , respectively, of the ejection side mold member  13 . The submolds  97 ,  99 ,  101 ,  103  have cavities  97 A,  97 B,  99 A– 99 G,  101 A,  103 A, which mate with submold cavities  27 A,  27 B,  29 A– 29 G,  31 A,  33 A, respectively, when the mold members  13 ,  15  are closed to form sealed, enclosed mold volumes for receiving molding material and forming the objects. 
   A sprue bushing  107  is received through a hole in the center of the clamp plate  89 . The sprue bushing  107  has a passage through it for injection of liquefied molding material to the submolds. The clamp plate  89  engages and supports the submolds  97 ,  99 ,  101 ,  103  against loads experienced during pressurized injection of molding material in the molding process. Thus, the clamp plate  89  maintains the submolds flush with the mold face  65  of the mold plate  93  of the static side mold member  15 . A locating ring  109  mounted on the back of the clamp plate  89  by locating ring screws  111  projects from the clamp plate and is received in a correspondingly shaped recess (not shown) in the fixed platen  11  for locating the static side mold member  15  relative to the fixed platen. 
   The mold plate  93  rests against the clamp plate  89  so that loads applied to the mold plate  93  are transferred to the clamp plate (and hence the fixed platen  11 ). There are two grooves  113  and  115  on each longitudinal side of the mold plate  93 . The rearward groove  115  of the two grooves is constructed for receiving a clamp (not shown) associated with the fixed platen  11  that tightly secures the static side mold member  15  to the fixed platen. Openings  117  on all four sides of the mold plate  93  permit connection of parts (described hereinafter) in the submold receptacle  95  to the hoses  23  of the cooling system  20 . Additional openings  118  allow the hoses  23  to connect to internal cooling passages (not shown, but nearly identical to the internal passages  88  of the mold plate  39 ) in the mold plate  93 . An eyebolt  119  connected to the mold plate  93  is used for handling the static side mold member  15 , such as to install the mold member in the plastic injection molding machine  1  and to remove the mold member from the machine. The mold plate  93  also has features which permit very precise registration with the mold plate  39  of the ejection side mold member  13 . Leader pins  121  attached to and extending through the mold plate  93  of the static side mold member  15  are received in the leader pin bushings  79  in the mold plate  39  of the ejection side mold member  13  for guiding the mold plates  39 ,  93  into engagement when the mold members are closed. Conical parting line lock studs  123  secured to the mold plate  93  by cap screws  125  are received in the parting line lock cups  81  just before the mold plates  39 ,  93  make contact for very fine registration (e.g., within thousandths of an inch) as the mold members  13 ,  15  close. The conical shape of the parting line studs  123  delays engagement with the parting line lock cups  81  until the last possible moment for final registration. 
   The ejection side mold member  13  and static side mold member  15  are shown assembled, but without the submolds in  FIG. 3 . The submold receptacle  77  of the ejection side mold member  13  is shown with partitions  131 ,  133 ,  135 , and the submold receptacle  95  of the static side mold member  15  is shown with partitions  137 ,  139 ,  141 , that divide their respective submold receptacles  77 ,  95  into four sections. The submold receptacle sections of the ejection side mold member  13  are designated  143 ,  145 ,  147  and  149 . The submold receptacle sections of the static side mold member  15  are designated  151 ,  153 ,  155  and  157 . Referring now also to  FIGS. 6–13 , the partitions  131 ,  133 ,  135  and  137 ,  139 ,  141  are capable of being variously positioned in the submold receptacles  77  and  95  of the mold members  13 ,  15  to create sections of different sizes for receiving different configurations of submolds.  FIG. 6  illustrates the partitions  131 ,  133 ,  135  of the ejection side mold member  13  of  FIG. 3  exploded from the mold member.  FIG. 7  illustrates the partitions  137 ,  139 ,  141  of the static side mold member  15  of  FIG. 3  exploded from the mold member. Except as noted, the constructions of the partitions  137 ,  139 ,  141  of the static side mold member  15  are the same as for the ejection side mold member  13  so that a description of the partitions  131 ,  133 ,  135  associated with the ejection side mold member will largely suffice for all partitions. 
   Referring again to  FIG. 6 , the partitions of the ejection side mold member  13  include a primary partition  131  and two secondary partitions  133 ,  135 . The primary partition  131  spans the full width of the submold receptacle  77  and is secured at opposite ends to the mold plate  39 . The secondary partitions  133 ,  135  extend from the primary partition  131  to an adjacent side of the submold receptacle  77 . As shown in  FIGS. 8 ,  9 ,  10  and  11 , the primary partition  131  comprises a body  167  made of a suitable material, such as a block of aluminum or steel. A particularly preferred aluminum alloy for the body  167  is sold under the trademark FORTAL. Preferably, the body  167  is formed of the same material as the mold plate  39  so that the two have identical or similar thermal expansion characteristics. 
   The body  167  is drilled and plugged to form two distinct internal passages  168  ( FIG. 10 ) for circulating coolant through the body. The body  167  may be broadly considered a “heat transfer member”. It will be understood that heat transfer members (not shown) may be placed in contact with the submolds  27 ,  29 ,  31 ,  33 ,  97 ,  99 ,  101 ,  103  (or with other submolds) for cooling the submolds without operating to partition the submold receptacle  77 ,  95  into sections. Such heat transfer members that do not function as partitions would have a different shape than the body  167 . The coolant loop passages  168  in the body  167  communicate with the cooling system  20  of the plastic injection molding machine  1  by way of pairs of fittings  169  screwed into the body on opposite ends. Each fitting  169  is aligned with (and received in) one of the holes  85  in the mold plate  39  for connection to one of the hoses  23  extending from the cooling system manifolds  21 ,  22  of the injection molding machine  1  (shown in  FIGS. 1 and 1A ). It is also possible to connect (using a separate conduit, not shown) one fitting  169  on one end of the body  167  to another fitting on an opposite end of the body so that the internal passages  168  within the body are placed in series (i.e., as a single coolant loop). Preferably a suitable quick connect/disconnect fastening arrangement (not shown) of the hoses  23  and fittings  169  is employed. 
   A runner channel plate  173  is mounted on top of the body  167  (broadly, “a substrate”) by bolts  175  that are threaded into inserts  177  screwed into the body ( FIG. 11 ). In the illustrated embodiment, the runner channel plate  173  is made of steel (e.g., P20 steel) for better wear results. The inserts  177  protect the aluminum body  167  from wear as the bolts  175  are taken out and screwed back in over the life of the partition  131 . However, it will be understood that the runner channel plate  173  can also be made of the same material as the body  167  without departing from the scope of the present invention. The runner channel plate  173  is also secured (along with the body  167 ) to the support plate  37  of the ejection side mold member  13  (see  FIG. 4 ) by long bolts  179  extending through the runner channel plate and body, and threaded into the support plate  37 . Still further, keys  181  are received in corresponding channels  183 ,  185  in the body  167  and in the underside of the runner channel plate  173  to secure the two together. The keys  181  are attached by screws  187  to the body  167  and are held in the channels  185  of the runner channel plate  173  by clamping achieved by the bolts  175 . The keys  181  are employed to restrict relative thermal expansion between the steel runner channel plate  173  and aluminum body  167 , which occurs because they are made of different materials. 
   The runner channel plate  173  has a longitudinally extending runner channel  191 , and a series of transversely extending runner channels  193  that direct the liquefied molding material into the various cavities  27 A,  27 B,  29 A– 29 G,  31 A,  33 A of the submolds  27 ,  29 ,  31 ,  33 . The configuration of the runner channels  191 ,  193  is not arranged for use with a particular submold or submolds. The submolds  27 ,  29 ,  31 ,  33  are configured so that they block the transversely extending runner channels  193  which are not needed. Referring to  FIG. 2 , it may be seen that, for example, only the transverse runner channel designated  193 ′ communicates molding material to submold  33 . The other transverse runner channels open into the sides of the submolds, which plug the transverse runner channels  193  not needed in the arrangement of submolds shown in  FIG. 2 . The primary partition  131  also has two runner channel shutoff valves  197  mounted on the runner channel plate  173  and projecting into the longitudinal runner channel  191  (FIG.  11 ). The runner channel shutoff valves  197  each have a generally “U” shape, and can be rotated about a vertical axis between an open position in which the U-shaped valve is aligned with the longitudinal runner channel  191  to permit flow past the valve, and a closed position in which the valve is turned transverse to the longitudinal runner channel and blocks the flow of molding material past the valve. A friction ring  199  associated with each shutoff valve  197  holds the valve in a selected rotational position so that the valve will not be inadvertently turned by flow of molding material. The friction can be overcome manually to select the position of each shutoff valve  197 . 
   A support panel  207  is attached by bolts  209  to the underside of the body  167 . The support panel  207  is engaged by multiple support pillars  211  that are secured to the support panel by threaded fasteners  213 . The support pillars  211  slidably extend through an ejector bar plate  215  and pin retainer plate  217  of a second ejector device (indicated generally at  219 ) associated with the primary partition  131 . The bottom ends of the pillars  211  pass through the pin retainer plate  47  and ejector bar plate  45  to abut the ejector housing  35  of the ejection side mold member  13 . Thus, loads applied to the primary partition  131  during molding operations are transferred to the ejector housing  35  and to the movable platen  7 . In addition, the end margins of the body  167  overlie and are pinned to ledges  71  of the support plate  37  of the ejection side mold member  13 . The support plate  37  and support pillars  211  cooperate to rigidly hold the partition  131 , so that an upper surface of the runner channel plate  173  is coplanar with the mold face  63  of the mold plate  39  at all times. The support panel  207  of the partition is located in the central opening  69  of the support plate  37 . The support panel  207  has ledges  223 ,  225  which project laterally outwardly from the sides of the body  167 . Ledges  223  projecting from opposite sides of the body near the center, support the secondary partitions  133 ,  135 . Pairs of oppositely extending ledges  225  nearer to the ends of the body  167  engage the undersides of respective submolds  27 ,  29 ,  31 ,  33  to support the submolds. The submolds  27 ,  29 ,  31 ,  33  are attached by threaded fasteners to the ledges  71 ,  223 ,  225  that they engage. It will be understood that the ledges  71  of the support plate  37  and the ledges  223 ,  225  of the support panel  207  cooperate to rigidly position the submolds  27 ,  29 ,  31 ,  33  and secondary partitions  133 ,  135  against movement back into the ejection side mold member  13  away from the plane of the mold face  63  of the mold plate  39 . 
   The second ejector device  219  is used to remove runners (not shown) that invariably reside in the runner channels  191 ,  193  of the runner channel plate  173  after an object has been molded. The second ejector device  219  includes the ejector bar plate  215  and pin retainer plate  217  previously described. The ejector bar plate  215  and pin retainer plate  217  are secured together by bolts  231 . The ejector bar plate  215  rests on the pin retainer plate  47  of the first ejector device  43  when the primary partition  131  is installed in the submold receptacle  77 . Thus, actuation of the first ejector device  43  causes the second ejector device  219  associated with the primary partition  131  to be actuated, meaning the ejector bar plate  215  and pin retainer plate  217  move toward the body  167  of the partition. A plurality of ejection pins  233  have heads that rest on the ejector bar plate  215  and are received in counterbores (not shown) on the underside of the pin retainer plate  217 . The ejection pins  233  extend through the pin retainer plate  217 , the support panel  207  and the body  167  to respective holes in the runner channels  191 ,  193  of the runner channel plate  173 . Steel sleeves  237  in the body  167  protect the body from wear as the steel ejection pins  233  slide back and forth in the body. Prior to ejection, when the ejector bar plate  215  is spaced farthest away from the body  167 , the distal ends of the ejection pins  233  are each generally flush with the bottom of runner channels  193 . When the second ejector device  219  is actuated, moving the ejector bar plate  215  and pin retainer plate  217  closer to the body  167 , the ejection pins  233  project out from the bottom of the runner channels  193 , pushing solidified molding material (runners) out of the runner channels  191 ,  193 . The ejector bar plate  215  and pin retainer plate  217  slide along the support pillars  211  as they move. 
   A sprue puller  239  looks similar to the ejection pins  233 , and extends through the pin retainer plate  217 , support panel  207  and body  167  in the same way as the ejection pins  233 . A steel sprue puller sleeve  241  in the body  167  protects the body from wear caused by movement of the sprue puller  239 . The sprue puller  239  extends into a hole  243  in the center of the runner channel plate  173 , and is shaped in a conventional manner for attaching to and pulling out the column of solidified molding material in the sprue bushing  107 . The primary partition  131  also has return pins  245 , which perform a function similar to the return pins  57  described above. The return pins rest on the ejector bar plate  215  of the second ejector device  219  and have heads received in counterbores (not shown) on the underside of the pin retainer plate  217 . The return pins  245  extend through the pin retainer plate  217 , support panel  207  and body  167 , and are received in notches  246  in the runner channel plate  173  near opposite ends of the runner channel plate. Sleeves  247  in the body  167  encircle the return pins  245  and protect the body from wear. Only two of the sleeves  247  are exploded from the body  167  in  FIG. 11 . The return pins  245  may engage the mold plate  93  of the static side mold member  15  when the mold members  13 ,  15  are brought together to push the ejector bar plate  215  to a fully retracted position away from the body  167 . The return pins  245  make certain that no ejection pin  233  is protruding into the runner channel  193  when molding material is being injected. 
   The ends of the runner channel plate  173  projecting out from the ends of the body  167  are received in respective partition locator recesses  255  formed in the mold plate  39  (see  FIG. 6 ). These recesses  255  can be precisely located when the mold plate  39  is machined for very accurate positioning of the primary partition  131 . The primary partition  131  extends transversely across the width of the submold receptacle  77 . 
   The secondary partitions  133 ,  135  of the ejection side mold member  13  have a construction substantially similar to the construction of the primary partition  131 , and so will not be described in detail. The corresponding parts have the same reference numerals as the parts of the primary partition  131 , followed by the letter “a” or “b”. The secondary partition  133  is shown in some additional detail in  FIGS. 8A ,  9 A and  10 A. The runner channel plates  173   a ,  173   b  are each shaped at one end to be received in a respective one of recesses  257  in the face  63  of the mold plate  39  of the ejection side mold member  13  for precise location of the partitions  133 ,  135  relative to the mold plate. The other end of each secondary partition  133 ,  135  has a dovetail shape that is received in a correspondingly shaped notch  259  in the runner channel plate  173  of the primary partition  131 . Two bolts  261  secure the dovetail end of each runner channel plate to the primary partition  131 . The bolts  261  are received in inserts  263  ( FIG. 11 ) in the partition body  167 . An additional pair of bolts  265  secure each secondary partition  133 ,  135  to the ledge  223  of the support panel  207  that underlies and supports the secondary partition where it abuts the primary partition  131 . Another pair of bolts  267  secure each secondary partition  133 ,  135  to one of the ledges  71  of the support plate  37 . The runner channel plate  173   a ,  173   b  of each secondary partition  133 ,  135  lies flush with the runner channel plate  173  of the primary partition so that a longitudinal runner channel  191   a ,  191   b  of the secondary partition aligns with a short transverse runner channel  191  of the primary partition  131  so that liquid molding material can flow into the runner channel plate of the secondary partition. 
   The secondary partitions  133 ,  135  also have runner channel shutoff valves  197   a ,  197   b  to selectively block or open portions of runner channels  191   a ,  191   b ,  193   a ,  193   b  in the runner channel plates  173   a ,  173   b  of the secondary partitions. The runner channel shutoff valves  197   a ,  197   b  have the same construction and operation as the runner channel shutoff valve  197  of the primary partition  131 . Internal coolant passages  271  in the body of the secondary partition  133  are illustrated in  FIG. 10A . There are only two fittings  169   a ,  169   b  for each body  167   a ,  167   b  of the secondary partitions. The internal passages  271  are formed in body in the same way (drilling and plugging) as the passages  168  of the primary partition  131 . The support panel  207   a ,  207   b  of each secondary partition  133 ,  135  has a single support ledge  223   a ,  223   b  on each side of the body  167   a ,  167   b  for supporting one of the submolds  27 ,  29 ,  31 ,  33 . However, the number of submolds supported by the ledges  223 ,  225 ,  223   a ,  223   b  of the support panels  207 ,  207   a ,  207   b  of the primary partition  131  and secondary partitions  133 ,  135  can be other than described without departing from the scope of the present invention. The secondary partitions also have second ejector devices  219   a ,  219   b  which are substantially similar to the second ejector device  219  of the primary partition  133 . 
   The submolds  27 ,  29 ,  31 ,  33  are sized smaller than the submold receptacle sections  143 ,  145 ,  147 ,  149  into which they are received. The amount by which the submolds  27 ,  29 ,  31 ,  33  are smaller is determined according to the expected thermal expansions of the submolds and partitions  131 ,  133 ,  135  in use. Generally, the spacing between the submolds  27 ,  29 ,  31 ,  33  and the adjacent partition  131 ,  133 ,  135  or side of the submold receptacle  77  is selected so that, when cool, the submolds can be easily slid into and out of the sections  143 ,  145 ,  147 ,  149 , but when warmed by pressurized injection of hot molding material, the submolds expand into engagement with the partition or mold plate at the side of the submold receptacle to promote conductive heat transfer between the submold and the partition or mold plate  39 . In the illustrated embodiment, the spacing is about 0.5 thousandths of an inch per inch of length of the side of the submold  27 ,  29 ,  31 ,  33 . In other words, if one side of the submold is five inches long, then the spacing between that side and the adjacent partition  131 ,  133  or  135  or side of the submold receptacle  77  would be 2.5 thousandths of an inch. However it is to be understood that depending on the materials used and the configuration of the submold, the spacing ratio could be different. Moreover, it is possible that one or more of the partitions  131 ,  133 ,  135  could expand into contact with the submold  27 ,  29 ,  31 ,  33 . For instance, if a partition (not shown) had internal heating rods for applying heat to the submold, the partition would expand before the submold. 
   The coolant in the internal passages  168 ,  271  of the partitions  131 ,  133 ,  135  can then offload the heat to the cooling system  20  of the plastic injection molding machine  1 . It is noted that each side of every submold  27 ,  29 ,  31 ,  33  engages a surface that is cooled by an internal cooling passage that removes heat to a location outside the mold  3 . In this way a highly efficient heat transfer from the submolds  27 ,  29 ,  31 ,  33  can be accomplished. The heat transfer is further augmented when the material of critical parts of the submolds and the bodies  167 ,  167   a ,  167   b  of the partitions  131 ,  133 ,  135  and mold plate  39  are made of aluminum (e.g., FORTAL aluminum alloy). 
   In the embodiment of  FIGS. 1–11 , the primary partition  131  and secondary partitions  133 ,  135  are used to divide the submold receptacle  77  of the ejection side mold member  13  into the four sections  143 ,  145 ,  147 ,  149 , receiving the four submolds  27 ,  29 ,  31 ,  33 .  FIG. 12  illustrates a configuration in which only the primary partition  131  is used, dividing the submold receptacle  77  into two sections  281 ,  283  containing two submolds, generally indicated at  285  and  287 . As shown in  FIG. 13 , by using the primary partition  131  and one secondary partition  135  the mold receptacle  77  can be divided into three sections  289 ,  291 ,  293  holding three submolds, generally indicated at  295 ,  297 ,  299 . It may be seen that the number of sections of the submold receptacle  77  can be changed not only along the length of submold receptacle, but also along its width (i.e., in directions which are perpendicular to each other). It is envisioned that within the scope of the present invention, partitions could be constructed so as to form other arrangements including greater numbers of mold receptacle sections for more submolds (not shown). Moreover, the ejection side mold member  13  could be used without any partitions  131 ,  133 ,  135 , receiving a single submold (not shown) in its submold receptacle  77 . 
   The partitions  137 ,  139 ,  141  of the static side mold member  15  have constructions which are very similar to the partitions  1  of the ejection side mold member  13  ( FIG. 7 ). A main difference is that none of the partitions  137 ,  139 ,  141  of the static side mold member  15  has an ejector device. The mold  3  is designed in a way known to those of ordinary skill in the art so that the molded object and attached runners remain with the ejection side mold member  13  when the mold members  13 ,  15  are separated. The primary partition  137  of the static side mold member  15  includes a body  167   c  which is mounted directly on the clamp plate  89  and is supported by the clamp plate. The body  167   c  has internal coolant passages and two pairs of fittings  169   c  for communication with these passages. A runner channel plate  173   c  mounted on the body  167   c  may be made of the same or different material than the body. As shown, the runner channel plate  173   c  is made of steel and the body  167   c  is made of aluminum. The runner channel plate  173   c  has ends which are received in recesses  311  in the mold plate  93  for precise positioning. The primary partition  137  has a center passage  313  extending through the body  167   c  and the runner channel plate  173   c  which receives the sprue bushing  107 . Thus, the sprue bushing  107  opens into the runner channels  191   c ,  193   c  of the primary partition runner channel plate  173   c  so that liquefied molding material flows into the runner channels. When the mold members  13 ,  15  are closed, the runner channels  191   c ,  193   c  of the primary partition  137  are aligned with the runner channels  191 ,  193  of the primary partition  131  of the ejection side mold member  13  to define completely enclosed passages in which the molding material may flow. The runner channel plate  173   c  further includes runner channel shutoff valves  197   c  for selectively closing off portions of the runner channels  191   c ,  193   c  from flow of molding material. The construction and operation of the shutoff valves  197   c  are the same as the shutoff valves  197  of the primary partition  131  of the ejection side mold member  13 . 
   The secondary partitions  139 ,  141  of the static side mold member  15  each also include a body  167   d ,  167   e  and runner channel plate  173   d ,  173   e , substantially as described for the secondary partitions  133 ,  135  of the ejection side mold member  13 . The runner channel plates  173   d ,  173   e  are shaped at one end for reception in recesses  321  in the mold plate  93 , and at an opposite end in a notch  259   c  in the primary partition runner channel plate  173   c . The primary partition  137  and secondary partitions  139 ,  141  of the static side mold member  15  can be arranged in different ways, corresponding to the arrangements of the partitions  131 ,  133 ,  135  of the ejection side mold member  13  shown in  FIGS. 11 and 12 . The secondary partitions  139 ,  141  are also mounted directly on the clamp plate  89  for their support. Thus, there is no support panel  207  such as is present with the partitions  131 ,  133 ,  135  of the ejection side mold member  13 . The secondary partitions  139 ,  141  each have an internal coolant passage (not shown) and two fittings  169   d ,  169   e  for liquid connection to the internal passage. Runner channels  191   d ,  193   d ,  191   e ,  193   e  in the runner channel plates  173   d ,  173   e  of the secondary partitions  139 ,  141  align with corresponding runner channels  191   a ,  193   a ,  191   b ,  193   b  in the secondary partitions  133 ,  135  of the ejection side mold member  13  to form enclosed passages. The runner channel plates  173   d ,  173   e  of the secondary partitions  139 ,  141  of the static side mold member  15  also have shutoff valves  197   d ,  197   e  to selectively close off portions of the runner channels  191   d ,  193   d ,  191   e ,  193   e  to molding material. The construction and operation of the shutoff valves  197   d ,  197   e  of the secondary partitions  139 ,  141  of the static side mold member  15  are the same as that of the shutoff valves  197 ,  197   a ,  197   b  of the primary and secondary partitions  131 ,  133 ,  135  of the ejection side mold member  13 . It will be appreciated that the location of the shutoff valves  197   c ,  197   d ,  197   e  of the partitions  137 ,  139 ,  141  of the static side mold member  15  are aligned with the shutoff valves  197 ,  197   a ,  197   b  of the partitions  131 ,  133 ,  135  of the ejection side mold member  13 . 
   Referring again to  FIG. 2 , the four submolds  27 ,  29 ,  31 ,  33  in the ejection side mold member  13  and the four submolds  97 ,  99 ,  101 ,  103  in the static side mold member  15  come in two general types. The first type of submold is represented by submold  27  which is shown in solid lines in  FIG. 17 , and also shown in  FIG. 18 . The phantom lines in  FIG. 17  illustrate a method of subtractive reconditioning of the submold  27 , which will be described hereinafter, but is not pertinent to the present description. Submold  27  is associated with the ejection side mold member  13  and comprises a unitary mold block  349 , which in the illustrated embodiment is aluminum (e.g., FORTAL aluminum alloy). The material could be steel or another suitable material within the scope of the present invention. An upper surface  351  of the mold block  349  is formed with a cavity, or as is the case with the submold  27 , two cavities  27 A,  27 B corresponding to the shape of approximately one half of an object to be molded. The submolds  31 ,  33  show examples where only single cavities ( 31 A,  33 A) for producing a single object are formed in the submolds. The upper surface  351  of the mold block  349  is formed with a runner channel  353  leading from an edge of the mold block where liquefied molding material is fed from the runner channel plate  173   a  into the mold block, and branch runner channels  355  leading from the runner channel to the respective cavities  27 A,  27 B. 
   The submold  27  has a third ejector device (generally indicated at  357 ) including an ejector bar plate  359  attached to a pin retainer plate  361 . Ejection pins  363  are mounted on the ejector bar plate  359  and pin retainer plate  361  in the same way as described for the ejection pins  233  associated with the second ejector device  219 . The ejection pins  363  extend through the pin retainer plate  361  and mold block  349  to openings in the cavities  27 A,  27 B and channels  353 ,  355  for pushing the object and connected runners out of the submold  27 . Return pins  365  captured by the ejector bar plate  359  and pin retainer plate  361  extend through the mold block  349  to the upper surface  351  of the mold block. A coil spring  367  surrounds each return pin  365  and bears against the pin retainer plate  361  and the underside of the mold block  349 , urging the ejector bar plate  359  back to a fully retracted position. As with the other return pins  233 , the free ends of the pins  365  are flush with the upper surface  351  of the mold block  349  if the ejector bar plate  359  is fully retracted. If the ejector bar plate  359  is not fully retracted, the return pins  365  will engage a mating surface of the submold  97  associated with the static side mold member  15  and push the ejector bar plate (and hence all of the ejection pins) back to the fully retracted position. 
   The ejector bar plate  359  rests on the pin retainer plate  47  of the first ejector device  43 . Thus, when the first ejector device  43  is actuated, the pin retainer plate  47  pushes the ejector bar plate  359  and pin retainer plate  361  of the third ejector device  357 , causing the ejection pins  363  to push the object and runners out of the submold  27 . When the ejector bar plate  45  of the first ejector device  43  is retracted, the coil springs  367  push the ejector bar plate  359  of the third ejector device  357  back to a retracted position so that the ejection pins  365  are substantially flush with bottoms of respective cavities  27 A,  27 B and/or channels  353 ,  355  in the mold block  349 . 
   A support pillar  371  extends through the ejector bar plate  359  and pin retainer plate  361  into threaded engagement with the underside of the mold block  349 . The opposite end of the support pillar  371  extends down through the pin retainer plate  47  and ejector bar plate  45  of the first ejector device  43  into engagement with the ejector housing  35 . In this way a center portion of the submold  27  is supported directly by the ejector housing  35 . Moreover, the support pillar  371  also connects the third ejector device  357  to the mold block. The lower end of the support pillar  371  is enlarged so that the ejector bar plate  359  rests on the support pillar, and the top end is fastened to the mold block  349 , attaching the third ejector device  357  to the mold block. As stated previously, the submold  27  also rests on ledges  71  associated with the support plate  37 , ledges  225  of the primary partition  131  and ledges  223   a  of the secondary partition  133 , which support the submold under the loads experienced during pressurized injection of molding material in the molding process. The submold  27  is attached to the ledges  71 ,  223   a ,  225  on which it is supported. In some instances, where the distance spanned by the mold block  349  between supporting ledges  71 ,  225  is relatively short, the support pillar  371  is not necessary. 
   Submolds  31  and  33  have a similar construction as the submold  27 , particularly in that they have their cavities  31 A,  33 A formed in respective, one piece mold blocks. Similarly, the corresponding submolds  97 ,  101 ,  103  associated with the static side mold member  15  also have their cavities  97 A,  97 B,  101 A,  103 A formed in unitary mold blocks. The mold blocks of the submolds  97 ,  101 ,  103  of the static side mold member  15  are attached directly to the clamp plate  89  of the static side mold member and are supported by the clamp plate. 
   The second type of submold is represented by the submold  29 , which is shown in more detail in  FIGS. 15 and 16 . The submold  29  is associated with the ejection side mold member  13  and has a fourth ejector device  391 . The submold  29  further includes a mold block (generally indicated at  393 ), which instead of being a unitary piece of material, comprises modular submold components  395 ,  397 ,  399 ,  401 ,  403 ,  405 ,  407  attached to a generally H-shaped frame (generally indicated at  409 ) including end pieces  411  and a center beam  413 . Each of the submold components  395 ,  397 ,  399 ,  401 ,  403 ,  405 ,  407  is a solid block of material (e.g., FORTAL aluminum alloy) into which is formed a respective one of the cavities  29 A– 29 G, corresponding to (approximately) one half of the object to be formed, and a runner channel  415 ,  417 ,  419 ,  421 ,  423 ,  425 ,  427 . One or more grooves  431  on one side of the submold components  395 ,  397 ,  399 ,  401 ,  403 ,  405 ,  407  (only some of the grooves may be seen in the drawings) receive a corresponding number of tongues  433  (only some are shown) formed on the center beam  413  to precisely locate the submold components relative to the frame  409  ( FIG. 16 ). The submold components  395 ,  397 ,  399 ,  401 ,  403 ,  405 ,  407  are made in widths of a fixed increment. Thus, the submold component  399  or  405  with two grooves is twice as wide as the submold component  395  having one groove, the submold component  403  having three grooves is three times as wide as the single groove submold component  395 , and the submold component  397  having four grooves is four times as wide. Submolds (not shown) as large as the one entire side of the center beam  413  are contemplated. Thus within the submold  29 , there is substantial flexibility as to the sizes of the objects which can be produced. However, the flexibility is achieved within the context of submold components  395 ,  397 ,  399 ,  401 ,  403 ,  405 ,  407  of predetermined sizes. A range of submold component blanks (not shown, but like the illustrated submold components  395 ,  397 ,  399 ,  401 ,  403 ,  405 ,  407  without a cavity or runner channels) can be provided for use in constructing the particular submold components to be used. A retainer plate  437  mounted by bolts  439  on the underside of the center beam  413  of the frame  409  is used for retaining the submold components  395 ,  397 ,  399 ,  401 ,  403 ,  405 ,  407  on the frame. The bolts  439  are received in inserts  441  screwed into the center beam  413 . The inserts  441  protect the frame material (e.g., FORTAL aluminum alloy) from premature wear cause by fastening and releasing the bolts  439 . 
   A runner channel plate  443  is mounted on top of the center beam  413  and is received in cutouts  445  in the end pieces  411 . Bolts  447  used to mount the runner channel plate  443  are also received in inserts  449  screwed into the end pieces  411  to protect the frame  409  from wear. The runner channel plate  443  cooperates with the retainer plate  437  to retain the submold components  395 ,  397 ,  399 ,  401 ,  403 ,  405 ,  407  on the frame. A longitudinal runner channel  451  of the runner channel plate  443  communicates with a transverse runner channel  193  of the primary partition  131  to receive liquefied molding material. Certain transverse runner channels  453  of the runner channel plate  443  are aligned with the runner channels  415 ,  417 ,  419 ,  421 ,  423 ,  425 ,  427  of the submold components  395 ,  397 ,  399 ,  401 ,  403 ,  405 ,  407  to deliver molding material to the submold components. Other transverse runner channels  453  are blocked by abutting portions of the submold components  395 ,  397 ,  399 ,  401 ,  403 ,  405 ,  407  away from the runner channels  415 ,  417 ,  419 ,  421 ,  423 ,  425 ,  427 . The runner channel plate  443  is one which is not particularly dedicated to a particular arrangement of submold components  395 ,  397 ,  399 ,  401 ,  403 ,  405 ,  407 , but can be used with different arrangements of submold components, including other submold components that are not illustrated. 
   The fourth ejector device  391  is similar to the third ejector device  357 , but has a modular construction to conform to different arrangements of submold components making up the submold  29 . As shown in  FIG. 15 , the fourth ejector device  391  includes an ejector bar plate  473  and a pin retainer plate  475  secured to the ejector bar plate by bolts  477 . Return pins  479  extend through the end pieces  411  of the submold frame  409 . Coil springs  481  are received around the return pins  479  between the pin retainer plate  475  the end pieces  411  of the frame  409 . The coil spring  481  in the foreground of  FIG. 15  has been mostly broken away to add clarity to the drawing. The return pins  479  function exactly the same way as the return pins  365  of the third ejector device  357 . Ejection pins  483  have heads which are retained between the pin retainer plate  475  and modular retainer plates  485 ,  487 ,  489 ,  491 ,  493 ,  495 ,  497  mounted on the pin retainer plate by screws  499 . 
   The ejection pins  483  extend up through modular ejector guides  501 ,  503 ,  505 ,  507 ,  509 ,  511 ,  513  that are received in pockets (not shown) formed on the undersides of respective submold components  395 ,  397 ,  399 ,  401 ,  403 ,  405 ,  407 . The smallest modular retainer plate  485  and ejection guide  501  correspond to the submold component  395  which is one base increment wide and has one groove  431 . Another modular retainer plate  495  and ejector guide  511  correspond to the submold component  405  which is two base increments wide, and so on. These modular retainer plates  485 ,  487 ,  489 ,  491 ,  493 ,  495 ,  497  and ejector guides  501 ,  503 ,  505 ,  507 ,  509 ,  511 ,  513  can be variously positioned on the pin retainer plate  475  as needed to arrange ejection pins  483  corresponding to the particular submold component with which the ejection pins need to operate. If the submold components are changed, then the ejection pins  483 , modular retainer plates  485 – 497  and modular ejection guides  501 – 513  can be changed. The fourth ejector device  391  functions in the same way as the third ejector device  357  to eject the objects formed in the cavities  29 A– 29 G of the various submold components  395 ,  397 ,  399 ,  401 ,  403 ,  405 ,  407  of the submold  29 . 
   The submold  29  is secured by pairs of fasteners  519  on each end to a ledge  71  on the support plate  37  and to another ledge  225  on the primary partition  131 . Sides of the submold  29  are supported by another ledge  71  of the support plate  37  and one of the ledges  223   a  of the secondary partition  133 . In addition, three support pillars  521  extend through the ejector bar plate  473  and pin retainer plate  475  into engagement with the underside of the submold  29  on the retainer plate  437 . The retainer plate translates the support of the support pillars  521  to all of the submold components  395 ,  397 ,  399 ,  401 ,  403 ,  405 ,  407 . The opposite ends of the support pillars  521  slidably extend through the pin retainer plate  47  and ejector bar plate  45  and rest directly on the ejector housing  35 . Thus, the support pillars  521 , ledges  71  of the support plate  37  and ledges  223 ,  223   a  of the partitions  131 ,  133  cooperate to support the submold  29  against the loads applied to the submold as a result of pressurized injection of molding material during the molding operation. The support pillars  521  also function to attach the fourth ejector device to the frame  409  of the mold block  393 . 
   Referring to  FIG. 14 , the corresponding submold  99  associated with the static side mold member  15  has a construction substantially similar to that of the submold  29  associated with the ejection side mold member  13 . The submold  99  includes modular submold components  551 ,  553 ,  555 ,  557 ,  559 ,  561 ,  563  which are mounted on a frame indicated generally at  565 . A runner channel plate  567  acts to direct molding material to the various submold components  551 – 563  in the same way as the runner channel plate  443 . However, the submold  99  of the static side mold member  15  does not have an ejector device like the fourth ejector device  391 . The submold  99  is attached directly to and supported by the clamp plate  89 . The submold  99  mates with the submold  29  of the ejection side mold member  13  to enclose molding volumes defined by mating cavities  29 A– 29 G and  99 A– 99 G, and runner passages defined by mating runner channels of the runner channel plates  443  and  567 . The mold  3  of the present invention thus provides for modularity by allowing for different arrangements of submolds, and also by having a modular submold which can be configured and reconfigured for molding different objects. 
   Over time, the submolds (and in particular the mold blocks and submold components) become worn and/or break in use, and are not capable of producing acceptable objects. It is well known to recondition mold blocks which are worn or damaged by cutting away a layer of the block which contains the wear or damage (“subtractive reconditioning”). The mold members  13 ,  15  are removed from the plastic injection molding machine  1 , the submold or submolds are taken out of the mold members and the mold blocks (or submold components) are removed from any remaining ancillary structure of the submolds. Typically, the mold blocks are placed in a computer numerical controlled (CNC) machine capable of cutting off (or otherwise removing) material from the submold upper surfaces. The CNC machine is capable of accessing electronic data regarding the original configuration of the submold. The original acquisition of this data may be part of a virtual cavity or virtual mold existing in electronic form that was created from customer product specifications in electronic form. The minimum amount of material that can be taken off of the upper surface of each mold block is determined by ascertaining how much material needs to be removed to eliminate damage and cause all surfaces of the mold cavities to be exposed and freshly cut. 
   In the method of the present invention, the depth of the cut is not arbitrary or peculiar to any one mold block, but is selected from a predetermined minimal cut depth increment and multiples of that increment. For instance in a preferred embodiment, the increment is 0.0625 inches, but other increments could be selected without departing from the scope of the present invention. A predetermined depth D 1  of cut removed from a reconditioned mold block  349  is illustrated in  FIG. 17  by the exploded upper surface section  591  shown above the mold block in phantom lines. In practice, the removed upper surface section  591  would not be cut away as a unit as shown, but has been illustrated as a cohesive unit for purposes of showing the cut depth D 1 . The depth D 1  of the section  591  has been greatly exaggerated in proportion to the size of the mold block  349  in this drawing so that it is more easily seen. The phantom line  593  below the existing upper surface  351  illustrates the depth D 2  to which the next cut will be made for subtractive reconditioning the mold block  349 . As shown, D 2  is the same depth as the amount D 1  previously cut away. However, the depth D 2  of the next cut could be a multiple of the first cut D 1  (assuming the first cut was to a depth equal to the minimum increment). The precise depth of the cut would be determined when the damage to the upper surface  351  is evaluated at the beginning of the next subtractive reconditioning of the mold block  349 . 
   Once the mold block upper surface has been cut to the predetermined depth and a new surface is exposed, a determination is made as to how the upper surface  351  will be finished. Almost always, the upper surface  351  is reformed with the same cavity (cavities  27 A,  27 B) as previously formed in the mold block  349 . The data for reforming the upper surface  351  of the mold block  349  is obtained from the aforementioned virtual cavity information. The data can be fed directly to a controller of a CNC machine (not shown) that reproduces the cavity and other features automatically. However, the data could also be used for a manual reconditioning of the mold block, or some combination of manual and automated reconditioning. If the cavity (e.g., cavities  27 A,  27 B) is to be reconditioned by bead blasting or other abrasive method, then a temporary protective layer (not shown) is placed at the depth of the mold parting line of the reconditioned mold block upper surface  351  prior to the onset of reconditioning of the cavity (i.e., after the predetermined increment of thickness has been cut away from the upper surface). After the cavity is reconditioned, the protective layer is removed. Abrasive reconditioning may damage the sharp edges of the cavities at the parting line surface (i.e., the upper surface  351 ). Thus after abrasive reconditioning, the mold block  349  may be returned to the CNC machine to sharpen the edges and form the upper surface  351  for close registration with the upper surface of the mating submold. 
   The reconditioned mold block  349  is not, by itself, suitable for use in the submold because it is now shorter and would not register with the plane of the mold face  63  of the mold plate  39 . Moreover, the travel of the ejection pins would not be proper for the reduced height of the reconditioned mold block. In order to compensate for the loss of height, a preconstructed set of shims (designated  601 ,  603 ,  605 ,  607 ) is provided ( FIG. 19 ). The number and thickness of shims  601 – 607  shown in  FIG. 19  are exemplary only. The same set of shims  601 – 607  would be used for the mold blocks of all submolds of any mold constructed according to the illustrated embodiment. The shims  601 – 607  come in thicknesses which correspond to the amount of the incremental cut depth of the mold block. In other words, the shims in the illustrated embodiment come in thicknesses of 0.0625 and multiples thereof. The particular shim  601 – 607  which is selected depends upon the total depth of material which has been removed from the upper surface  351  of the mold block  349  after all subtractive reconditioning procedures. Multiple shims can be selected to equal the total depth of material removed. As is shown in  FIG. 18 , two shims  601  and  607  of different thicknesses (e.g., 0.250 inch and 0.0625 inch) are used with the mold block  349  in the reconditioned submold  27 . The shims  601 ,  607  are attached by bolts  609  on the underside of the mold block  349  so that as assembled in the submold  27 , the mold block will extend up to the same height it did originally, prior to removal of any material from the upper surface  351 . Although the shims  601 – 607  are shown as closed loops of material, they may be formed by one or more distinct segments of material (not shown) mounted on the underside of the mold block  349 . 
   Typically, the shims  601 – 607  are made of a harder material than the mold block  349 . However, when the material of the shims  601 – 607  is different, the amount of thermal expansion among the different submolds in the mold member  13  or  15  may be different. The expansion differentials may be unacceptable in some circumstances. By considering factors such as the coefficient of thermal expansion of each material, the viscosity of molding material, injection pressure of mold material and range of operation temperatures, a maximum ratio of height of shims of differing material to the existing mold block height can be determined. If the ratio will be exceeded by using a single shim having a thickness corresponding to the full thickness of material removed from the mold block, then two shims can be used (e.g., shims  601  and  607 , as shown in  FIG. 18 ). The thinner shim  601  would be made of the harder material and the thicker shim  607  would be made of the same material as the mold block  349  (e.g., FORTAL aluminum alloy). The thicker shim  607  would have to be thick enough so that the ratio of the thickness of the thinner shim  601  of harder material to the thickness of the mold block material (now including the thickness of the thicker shim  607 ) was below the maximum allowed. 
   Ejection pins  365  and other submold parts are individually measured to determine whether reconditioning is needed. Often, these other parts are constructed of a hardened material and require reconditioning less frequently. If the pins  365  are found to be excessively worn, they are replaced. Guide holes for the pins are also measured for wear. If excessive wear in the guide holes is found, the holes are reconditioned. Either larger ejection pins are used for the guide holes of now larger diameter, or inserts (not shown) are placed in the guide holes so that the same ejection pins can be used. 
   The mold  3  of the present invention retains the flexibility for the customer to reconfigure the mold should market conditions require, for instance, a larger number of objects to be produced in a given time. If a higher output of objects is needed, it is not necessary to construct an entirely new mold. Instead, the virtual cavity can be used to create additional submolds that are received in the same mold plate. A different number of partitions can be used to provide more submold receptacle sections to receive a greater number of submolds. In addition, or as an alternative, the submold with submold components can be reconfigured to make more parts. In any event, the customer does not have to incur the full costs associated with creating an entirely new mold. Of course, if all available space in the mold plate is already filled, the cost of making a new mold will have to be incurred. However, even then the pre-existence of the virtual cavity data will make the construction of the second mold more efficient and less costly than with conventional molds. 
   Referring now to  FIG. 20 , mating pairs of submolds of a second embodiment are shown to comprise an ejection side submold  651  and a static side submold  653  (the reference numerals designating their subjects generally). The submolds  651 ,  653  are shown side-by-side rather than in opposed relation as they would be in use. The static side submold  653  has substantially the same construction as the static side submolds  97 ,  99 ,  101  and  103  of the first embodiment and can be mounted directly on the clamp plate  89  of the static side mold member  15 . The static side submold  653  has multiple cavities  655  each having an associated runner channel  657  and runner channel shutoff valve  659 . The ejection side submold  651  is similar to the ejection side submolds  27 ,  29 ,  31 ,  33 , except that it has a modular height feature, as will be described. The ejection side submold  651  includes a fifth ejector device (generally indicated at  663 ) comprising an ejector bar plate  665 , a pin retainer plate  667 , ejection pins  669 , return pins  671  ( FIG. 22 ) and return springs  672 . A support pillar  673  extends through the ejector bar plate  665 , pin retainer plate  667  and attaches to the underside of the cavity block  677 . In addition to providing support for the submold  651  in use, the support pillar  673  attaches the fifth ejector device  663  the submold. 
   The submold  651  further includes a mold block  675  comprising a cavity block  677  and a modular wall  679  (all numerals indicating their subjects generally). The cavity block  677  is made of a solid piece of material and has cavities  681  formed in it for shaping a portion of a molded object. The cavity block  677  is also formed with runner channels  683  and corresponding runner channel shutoff valves  685 . The wall  679  engages the underside of the cavity block  677 . When placed in the submold receptacle  77  of the mold member  13 , the underside of the wall  679  engages support ledges  71 ,  223   a ,  225  of the support plate  37 , the primary portion  131  and one of the secondary partitions  133 ,  135  that may be mounted in the submold receptacle  77  (not shown in  FIGS. 21–24 ). The wall  679  comprises multiple (four in the illustrated embodiment) wall members  687  that form a rectangle with an open center (see  FIG. 22 ). The wall members  687  engage respective ledges  71 ,  223   a ,  225  and are secured to the ledges by threaded fasteners. It will be understood that the number of wall members  687  making up the wall  679  can be other than described without departing from the scope of the present invention. Moreover, the wall may be formed by a solid block of material. 
   Referring to  FIGS. 23 and 24 , the same basic assembly is used to construct submolds (designated  651 ′ and  651 ″, respectively) having cavity blocks  677 ′,  677 ″ of different heights. Although each cavity block  677 ,  677 ′,  677 ″ has the same arrangement of cavities  681 ,  681 ′,  681 ″, cavity blocks having different cavities may be (and most likely would be) used in the different submolds. The cavity block  677 ′ of submold  651 ′ shown in  FIG. 23  is thicker than the cavity block  677  of the submold  651  of  FIG. 21 . Accordingly, the wall  679 ′ has wall members  687 ′ which are shorter so that the overall height of the submold remains the same.  FIG. 24  illustrates the submold  651 ″ having a thinner cavity block  677 ″ than the cavity block  677  of the submold  651  ( FIG. 21 ). The wall  679 ″ of submold  651 ″ is higher than the wall  679  of submold  651  to compensate for the difference. Again, the overall height of the submold  651 ″ remains the same as the submold  651  through use of different modular wall members  687 ″. When the objects to be molded are small and only relatively shallow mold cavities are required in the cavity block, it is permissible to use thinner cavity blocks. The walls  679 ,  679 ′,  679 ″ use less material (e.g., aluminum) than a solid mold block, and therefore is less costly to construct. The same walls  679 ,  679 ′,  679 ″ can be used with many different cavity blocks (not shown). Moreover, none of the walls  679 ,  679 ′,  679 ″ are used when the cavity block (not shown) is the full height. The support pillars  673 ,  673 ′,  673 ″ have extensions  673 A,  673 B,  673 C corresponding to the heights of the respective walls  679 ,  679 ′,  679 ″ so that the support pillars can extend to the cavity blocks  677 ,  677 ′,  677 ″. Only a minimum of material must be dedicated to any particular cavity block. Similar modular walls could be used for submolds (not shown) mounted on the static side mold member  15  without departing from the scope of the present invention. 
     FIG. 25  illustrates a modified version of the submold of  FIGS. 21 and 22 . The same parts from FIGS.  21  and  22  are indicated by the same reference numerals. A modified ejector bar plate  665   a  and pin retainer plate  667   a  are indicated by the same reference numerals plus the letter “a”. More specifically, the pin retainer plate  667   a  comprises a frame  691  and a center portion  692  that can be separated from the frame. The center portion  692  has pin guide holes  693  which line up with the ejection holes (not shown) in the cavities  681   a  of the particular cavity block  677   a  used in the submold  651   a . The ejector bar plate  665   a  has a center recess  695  what receives part of the center portion  692  when the plates  665   a ,  667   a  are assembled in use. Thus, the parts of the submold  651   a  other than the cavity block  677  are completely modular for use with other cavity blocks (not shown) having different arrangements of cavities. 
   When introducing elements of the present invention or the preferred embodiment(s) thereof, the articles “a”, “an”, “the” and “said” are intended to mean that there are one or more of the elements. The terms “comprising”, “including” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements. The use of terms indicating a particular orientation (e.g., “top”, “bottom”, “side”, etc.) is for convenience of description and does not require and particular orientation of the item described. 
   As various changes could be made in the above without departing from the scope of the invention, it is intended that all matter contained in the above description and shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.