Abstract:
Embodiments of the invention relate to injection mold components, assemblies, and molding system that include superhard materials. Such injection mold components, assemblies, and systems may decrease wear of certain injection mold components, which may result in improved productivity of the injection mold and molding systems that utilize such components.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 14/196,418 filed on 4 Mar. 2014, which is a continuation of U.S. patent application Ser. No. 13/463,471 filed on 3 May 2012 (now U.S. Pat. No. 8,702,412 issued on 22 Apr. 2014), which is a continuation-in-part of U.S. patent application Ser. No. 13/005,212 filed on 12 Jan. 2011 (now U.S. Pat. No. 8,512,023 issued on 20 Aug. 2013), the disclosure of each of which is incorporated herein, in its entirety, by this reference. 
    
    
     BACKGROUND 
     Injection molding processes have relatively widespread use and may be employed to produce a wide variety of parts. For instance, injection molded parts may range from only a few millimeters in size to parts that are several meters wide. Injection molding also may be used produce components that have various geometries, complexity of which may vary from simple to highly intricate in detail. Furthermore, injection molding processes may produce parts from various materials, including but not limited to thermoplastic polymers, aluminum alloys, zinc alloys, etc. 
     Oftentimes, molds used to manufacture injection molded parts (i.e., injection molds) may be relatively expensive. Consequently, injection molding is most commonly used to manufacture parts in large quantities. This may allow the cost of the injection mold to be amortized over thousands or even hundreds of thousands of molded parts. 
     Typical molds are constructed from metallic materials, such as steel, aluminum, brass, copper, etc. Usability of the mold may vary based on the materials used therein. For example, use of softer and/or less wear-resistant metals, which may exhibit increased wear in an injection mold, may lead to unusable parts produced by the mold. Ordinarily, material wear results from “cycling” the mold—i.e., closing the mold, injecting molten molding material, opening the mold, and/or ejecting or removing the parts. The rate and/or amount of wear may depend on the part geometry, molding material used in the process, frequency and number of cycles, and other factors present during the operation of the mold. 
     Additionally, an injection mold may include certain components that may exhibit more wear than other components, due to the nature of the operation of the mold. Thus, in some instances, a typical mold may require repair or replacement where increased wear may lead to failure of such components. 
     SUMMARY 
     Various embodiments of the invention are directed to injection mold assemblies and components that comprise a superhard material, as well as injection molding system that may utilize such injection mold assemblies and components. Superhard materials may be arranged and formed in any number of sizes and configurations. In some embodiments, superhard materials may be available in limited sizes. Hence, multiple segments may be used to enable forming desired surface sizes and configurations, notwithstanding possible limitations in the size of available superhard materials. Superhard materials also may be located along all or portion of one or more surfaces of the injection mold component, to form one or more wear-resistant surface, which may provide increased resistance to wear for such surfaces of the injection mold component. 
     According to one embodiment, an injection mold component for use in an injection mold includes a substrate and a superhard material bonded to the substrate that forms a wear-resistant surface. The wear-resistant surface is moveable within the injection mold, and/or the wear-resistant surface defines at least a portion of a conduit for communicating a molding material flows into the injection mold. 
     According to another embodiment, an injection mold assembly includes a first mold plate, a second mold plate, and one or more molding elements located on one or more of the first or second mold plates. The injection mold assembly also includes an injection mold component located on at least one of the first mold plate, on the second mold plate, or on the molding element. The injection mold component includes a superhard material forming at least a portion of a surface of the injection mold component, wherein the superhard material is bonded to a substrate. 
     According to yet another embodiment, an injection molding system includes an injection molding machine and an injection mold operably coupled to the injection molding machine. The injection mold includes a stationary portion, a moving portion, and one or more molding elements located on the stationary and/or on the moving portions. The injection mold also includes an injection mold component located on the stationary portion and/or on the moving portion. The injection mold component includes a superhard material forming a wear-resistant surface on the injection mold component. The superhard material is bonded to a substrate. The injection molding machine is configured to move the moving portion. The injection molding machine is also configured to inject molding material into the injection mold via a conduit at least partially defined by the wear-resistant surface of the injection mold component; or the wear-resistant surface is moveable within the injection mold. 
     Features from any of the disclosed embodiments may be used in combination with one another, without limitation. In addition, other features and advantages of the present disclosure will become apparent to those of ordinary skill in the art through consideration of the following detailed description and the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The drawings illustrate several embodiments of the invention, wherein identical reference numerals refer to identical or similar elements or features in different views or embodiments shown in the drawings. 
         FIG. 1  is a schematic cross-sectional view of an injection molding machine and an injection mold, which may utilize any of the injection mold components disclosed herein; 
         FIG. 2  is a cross-sectional view of an injection mold in accordance with one embodiment of the invention; 
         FIG. 3A  is a cross-sectional view of sprue bushing of an injection mold in accordance with one embodiment of the invention; 
         FIG. 3B  is a cross-sectional view of a sprue bushing of an injection mold in accordance with another embodiment of the invention; 
         FIG. 3C  is a cross-sectional view of a sprue bushing of an injection mold in accordance with yet another embodiment of the invention; 
         FIG. 3D  is a cross-sectional view of a hot runner system and various hot tips in accordance with one embodiment of the invention; 
         FIG. 3E  is a cross-sectional view of a gate insert of an injection mold in accordance with one embodiment of the invention; 
         FIG. 4A  is a cross-sectional view of a locating ring of an injection mold in accordance with one embodiment of the invention; 
         FIG. 4B  is a cross-sectional view of a locating ring of an injection mold in accordance with another embodiment of the invention; 
         FIG. 5A  is a cross-sectional view of an ejector sleeve of an injection mold in accordance with one embodiment of the invention; 
         FIG. 5B  is a cross-sectional view of an ejector sleeve of an injection mold in accordance with another embodiment of the invention; 
         FIG. 5C  is a cross-sectional view of an ejector sleeve of an injection mold in accordance with yet another embodiment of the invention; 
         FIG. 5D  is a cross-sectional view of a different embodiment of an ejector sleeve of an injection mold in accordance with one embodiment of the invention; 
         FIG. 5E  is a cross-sectional view of yet another embodiment of an ejector sleeve of an injection mold in accordance with one embodiment of the invention; 
         FIG. 6A  is a cross-sectional view of an undercut relief system of an injection mold in accordance with one embodiment of the invention; 
         FIG. 6B  is a cross-sectional view of the undercut relief system of  FIG. 6A  taken along line  6 B- 6 B thereof; 
         FIG. 6C  is a cross-sectional view of an undercut relief system of an injection mold in accordance with another embodiment of the invention; 
         FIG. 6D  is a cross-sectional view of an undercut relief system of an injection mold in accordance with yet another embodiment of the invention; 
         FIG. 6E  is a cross-sectional view of an undercut relief system of an injection mold in accordance with another embodiment of the invention; 
         FIG. 6F  is an isometric view of an undercut relief system of an injection mold in accordance with yet another embodiment of the invention; 
         FIG. 6G  is an isometric view of an undercut relief system of an injection mold in accordance with yet another embodiment of the invention; 
         FIG. 7A  is a cross-sectional view of a slide retainer in accordance with one embodiment of the invention; 
         FIG. 7B  is a cross-sectional view of a slide retainer in accordance with another embodiment of the invention; 
         FIG. 8A  is an isometric view of a rectangular two-plate interlock pair in an open position in accordance with one embodiment of this invention; 
         FIG. 8B  is an isometric view of a rectangular two-plate interlock pair in a closed position in accordance with another embodiment of this invention; 
         FIG. 8C  is a side view of a three-plate interlock pair in an open position in accordance with one embodiment of this invention; 
         FIG. 8D  is a side view of a three-plate interlock pair in a partially closed position in accordance with another embodiment of this invention; 
         FIG. 8E  is an isometric view of a tapered interlock pair in accordance with one embodiment of this invention; 
         FIG. 8F  is a side view of a tapered interlock pair in a closed position in accordance with another embodiment of this invention; 
         FIG. 8G  is an isometric view of a cylindrical tapered interlock pair in accordance with one embodiment of this invention; and 
         FIG. 8H  is a cross-sectional view of a cylindrical tapered interlock pair in a closed position in accordance with another embodiment of this invention. 
     
    
    
     DETAILED DESCRIPTION 
     Various embodiments of the invention are directed to injection mold assemblies and components that comprise a superhard material, as well as injection molding system that may utilize such injection mold assemblies and components. Superhard materials may be arranged and formed in any number of sizes and configurations. In some embodiments, superhard materials may be available in limited sizes. Hence, multiple segments may be used to enable forming desired surface sizes and configurations, notwithstanding possible limitations in the size of available superhard materials. Superhard materials also may be located along all or portion of one or more surfaces of the injection mold component, to form one or more wear-resistant surface, which may provide increased resistance to wear for such surfaces of the injection mold component. 
     There are numerous types of injection molding machines and techniques available for manufacturing injection molded parts. In particular, the injection molding machine may inject, for example, molten thermoplastics, thermosets, elastomers, aluminum alloys, and zinc alloys into an injection mold, to manufacture various parts from such materials or combinations thereof. Additionally, the injection molding machine may inject thermoplastics, thermosets, elastomers, or combinations thereof that incorporate metallic powder, thereby producing a “green” part, which may allow the manufacturer to make metal parts by removing the polymer material from the “green part” and sintering the metallic powder.  FIG. 1  illustrates an injection molding system  100 , which may include an injection molding machine  110  and an injection mold  120  (shown in a closed position). Although the particular configuration or operation of the injection molding machine  110  may vary in some regards with respect to other available machines or processes, the injection molding machine  110  may be a typical machine used for manufacturing injection molded parts. 
     The injection molding machine  110  may include a front platen  111  and a back platen  112 . The back platen  112  may move with respect to the front platen  111 , which may cause the injection mold  120  to open. In particular, the injection mold  120  may have a stationary portion  121  and a moving portion  122 , which may define a parting line  123  (i.e., the line (or one or more planes) along which the injection mold  120  splits to open). The stationary portion  121  of the injection mold  120  may be secured to the front platen  111  and the moving portion  122  may be secured to the back platen  112 . Accordingly, movement of the back platen  112  in a direction away from the front platen  111  may cause the moving portion  122  of the injection mold  120  to move away from the stationary portion  121 , thereby opening the injection mold  120  along the parting line  123 . Similarly, movement of the back platen  112  toward the front platen  111  may cause the injection mold  120  to close. 
     The injection molding machine  110  also may include a material hopper  113  and an injection system  114 , which may supply molten molding material into the injection mold  120 . More particularly, molding material (e.g., plastic pellets) may be added into the material hopper  113  and fed into the injection system  114 . In one embodiment, the injection system  114  may include a screw  115  that may rotate within a barrel. Optionally, one or more heaters  116  may surround the barrel to heat and/or at least partially or completely melt the molding material. 
     The melted molding material may be conveyed by the screw  115 , which may be a reciprocating screw, toward the injection mold  120 . The molten molding material may be injected into the injection mold  120  through an injection nozzle  117 . It should be noted that other configurations of the injection molding machine  110  may be used to manufacture molded parts. For instance, the injection system  114  may include a plunger, which may replace or may be incorporated into the screw  115 , and which may inject the molten molding material into the injection mold  120 . 
     Once the injection mold  120  is in a fully closed position (as shown in  FIG. 1 ), molten molding material may be injected into the injection mold  120 . More specifically, the molten material may fill a molding volume  131  within the injection mold  120 . Subsequently, as shown in  FIG. 2 , the molten molding material may cool and at least partially solidify to form a part corresponding to the molding volume  131 . When the molten molding material forming the part has cooled to a desired temperature, the injection mold  120  may be opened, by moving the back platen  112  away from the front platen  111  (as described above), and the part may be ejected or removed from the injection mold  120 . 
     To produce the part, the injection mold  120  may incorporate various molding elements, which may have necessary shapes and sizes to form a part  130 . For example, as illustrated in  FIG. 2 , the injection mold  120  may include one or more molding elements  140 , such as molding elements  140   a ,  140   b ,  140   c  (which may include a cavity, a core, a core pin, core inserts, etc.) that assemble to define the molding volume  131 . A “molding element” refers to any portion of the injection mold  120  that forms at least a portion of the part  130  (i.e., portion(s) of the injection mold  120  that define the molding volume  131 ). Thus, to produce multiple parts in a single cycle, the injection mold  120  may include multiple sets of molding elements  140 , which may be substantially identical (to produce the same parts) or may vary, for production of different parts in the single cycle. A “set of molding elements” refers to the molding elements  140  that, when combined, form or define the molding volume  131  (see  FIG. 1 ), which may accept molten material and form the part  130 . 
     As described above, the injection mold  120  may be secured in the injection molding machine  110 . More specifically, the injection mold  120  may be secured to the front platen  111  and back platen  112 . For instance, the nonmoving portion  121  of the injection mold  120  may have one or more clamping grooves that may accommodate clamps for securing the nonmoving portion  121  to the front platen  111  of the injection molding machine  110 . For example, the nonmoving portion  121  may include one or more plates, such as a first plate  121   a  and a top clamping plate  121   b , which may form such clamping grooves. The nonmoving portion  121  also may include an overhang that may accommodate clamps, bolt holes that may accept bolts for securing the nonmoving portion  121  to the front platen  111 , and/or other features that may be used to secure the nonmoving portion  121  to the front platen  111 , which should be appreciated by those skilled in the art. 
     The nonmoving portion  121  also may include a sprue bushing  150 , which may channel the molten molding material into the injection mold  120 . For example, the injection nozzle  117  may have a spherical tip which may contact a sphere of the same or similar radius on the sprue bushing  150 . Subsequently, the molten molding material may flow from the injection system  114  of the injection molding machine  110 , through the injection nozzle  117 , through the sprue bushing  150 , and into the injection mold  120 . In some instances, the nonmoving portion  121  also may include a locating ring  160 , which may aid in aligning the injection mold  120  and/or the sprue bushing  150  with the injection molding machine  110  as well as with the injection nozzle  117 . 
     The moving portion  122  of the injection mold  120  may be connected to the back platen  112  of the injection molding machine  110 . Similar to the nonmoving portion  121 , the moving portion  122  may incorporate a clamping groove or other features that may allow the manufacturer to connect the moving portion  122  of the injection mold  120  to the back platen  112  of the injection molding machine  110 . Furthermore, the moving portion  122  may include a second plate  122   a  that may secure or incorporate the molding element  140   b . The moving portion  122  of the injection mold  120  also may include a support plate  122   b , which may provide support to the second plate  122   a  and additional rigidity to the injection mold  120 . 
     Additionally, the moving portion  122  and the nonmoving portion  121  of the injection mold  120  may include leader pins and corresponding bushings (not shown), which may aid in aligning the moving portion  122  and the nonmoving portion  121  during the opening and closing of the injection mold  120 . In some embodiments, it may be desirable to provide additional alignment mechanisms, to further align the moving and the nonmoving portions  122 ,  121  of the injection mold  120  as well as to prevent undesirable movement of the nonmoving and moving portions  121 ,  122  during injection of the molding material. For example, as further described below, the injection mold  120  may include interlock pairs  280 , which may comprise male and corresponding female interlock portions. Furthermore, clearance between the male and the corresponding female interlock portions may be substantially smaller than the clearance between the leader pins and corresponding bushings. For instance, the clearance between the male and female interlocks may be in the range of 0.0002 inch to 0.0005 inch per side. 
     The injection mold  120  also may incorporate an ejection mechanism, which may eject the part  130  after the part  130  has cooled down to a desired temperature. In particular, the ejection mechanism may include an ejector housing  122   c  and ejector plates  122   d . For example, the ejector plates  122   d  may connect to an ejection system of the injection molding machine  110 , which may move the ejector plates  122   d  toward the front platen  111 . The ejector plates  122   d , in turn, may secure one or more ejector pins  170 , which may move together with the ejector plates  122   d  and eject the part  130  out of the injection mold  120 . 
     In some embodiments, as further described below, the injection mold  120  also may incorporate one or more ejector sleeves, such as ejector sleeves  220   a ,  220   b . More particularly, the ejector sleeve  220   a  may guide the ejector pin  170  through the molding element  140   b . Hence, a portion (e.g., a top surface) of the ejector sleeve  220   a  may contact the part  130  and may at least in part form the molding volume  131 . 
     In at least one embodiment, a core pin  140   c  may be secured in the ejector housing  122   c . The core pin  140   c  may at least in part define the molding volume  131  (e.g., the core pin  140   c  may form a hole in the part  130 ). The ejector sleeve  122   b  may provide additional uniformity during ejection of the part  130 . More specifically, the ejector plates  122   d  also may secure one or more ejector sleeves, such as the ejector sleeve  122   b , which may slide about the core pin  140   b , thereby aiding in ejection of the part  130 . 
     It should be appreciated that the injection mold  120  may include all, some, and/or additional molding elements, plates, and/or devices described herein. For instance, the injection mold  120  may have no ejector housing or ejector plates, and the manufacturer may choose to remove the parts with a robotic arm (or manually) to avoid ejector pin marks on the parts. Additionally or alternatively, the injection mold  120  may also include additional plates and/or devices, not described herein, which may be necessary for operation. For example, in lieu of ejector pins, the manufacturer may choose to use a stripper plate (where applicable), which may strip the part  130  from the molding element  140   b . Thus, it should be noted that components described herein may be used in the injection mold  120  of any configuration or design. 
     In some instances, the part  130  may include undercuts or undercutting portions, which may need to be relieved before the part  130  may be ejected from the injection mold  120 . In particular, one or more slides or lifters may be used to relieve undercuts and allow the part  130  to be ejected, as described in more detail below. A slide may move substantially orthogonally with respect to the undercut, thereby removing at least a portion of the molding element  140  away from the part  130 . A lifter may move in a direction of ejection (i.e., toward the front platen  111 ) and orthogonally to the undercut—thus, ejecting the part while relieving the undercut. 
     In at least one embodiment, one or more surfaces of one or more components comprising the injection mold  120  may include one or more layers of superhard material. More particularly, one or more layers of superhard material may form one or more wear-resistant surfaces on the injection mold components. An “injection mold component” refers to any component and/or element comprising an injection mold. Also, as used herein, the term “superhard,” or the phrase “superhard material,” refers to any material having a hardness that is at least equal to the hardness of tungsten carbide. Furthermore, element numbers denoted with letters “sm” identify superhard material in particular embodiments. It should be noted that so denoted superhard material may be any superhard material disclosed herein. Similarly, element numbers denoted with letters “wr” identify wear-resistant surface that may be formed by one or more layers of superhard material on a particular injection mold component. 
     In some embodiments, one or more substrates may be bonded to the injection mold components. The substrates may be a cobalt-cemented tungsten carbide substrate or other carbide substrate. Additionally, the layer of superhard material forming the wear-resistant surface may be natural diamond, polycrystalline diamond, polycrystalline cubic boron nitride, silicon carbide, diamond grains bonded together with silicon carbide, or any combination of the preceding materials. Furthermore, the superhard material may be thermally-stable diamond in which a catalyst material (e.g., iron, nickel, cobalt, or alloys thereof) has been at least partially depleted from a surface or volume of the polycrystalline diamond using, for example, a leaching process. A cemented carbide substrate (e.g., cobalt cemented, nickel cemented, cemented using alloys of cobalt, or cemented using alloys of nickel) may comprise any suitable carbide, such as tungsten carbide, tantalum carbide, vanadium carbide, niobium carbide, chromium carbide, titanium carbide, or combinations of the foregoing carbides. 
     In at least one embodiment, the superhard material includes one or more polycrystalline diamond compacts (PDCs). For instance, the substrate may comprise cobalt-cemented tungsten carbide and the layer of superhard material may include polycrystalline diamond. Such structures may be fabricated by subjecting diamond particles, placed on or proximate to a cobalt-cemented tungsten carbide substrate, to a high-pressure/high-temperature (HPHT) sintering process. The diamond particles with the cobalt-cemented tungsten carbide substrate may be HPHT sintered at a temperature of at least about 1000° Celsius (e.g., about 1100° C. to about 1600° C.) and a pressure of at least about 4 GPa (e.g., about 5 GPa to about 9 GPa) for a time sufficient to consolidate and form a coherent mass of bonded diamond grains. In such a process, the cobalt from the cobalt-cemented tungsten carbide substrate sweeps into interstitial regions between the diamond particles to catalyze growth of diamond between the diamond particles. More particularly, following HPHT processing, the superhard material may comprise a matrix of diamond grains that are bonded with each other via diamond-to-diamond bonding (e.g., sp 3  bonding), and the interstitial regions between the diamond grains may be at least partially occupied by cobalt or another catalyst, thereby creating a network of diamond grains with interposed cobalt or other catalyst, otherwise known as polycrystalline diamond (PCD). 
     In some embodiments, the catalyst used for forming the PCD superhard material may be a metal-solvent catalyst, such as cobalt, nickel, iron, or alloys thereof. A thermal stability of such PCD superhard material may be improved by leaching the metal-solvent catalyst from of the PCD. Leaching may be performed in a suitable acid, such as aqua regia, nitric acid, hydrofluoric acid, or combination thereof, so that the leach PCD superhard material is substantially free of metal-solvent catalyst. Furthermore, the PCD superhard material may be entirely or partially. Generally, a maximum leach depth may be greater than 250 μm. For example, the maximum leach depth may be greater than 300 μm to about 425 μm, greater than 350 μm to about 400 μm, greater than 350 μm to about 375 μm, about 375 μm to about 400 μm, or about 500 μm to about 650 μm. 
     The superhard material comprising the PCD also may allow operation of various components of the injection mold without lubricants. Thus, incorporating superhard material into injection mold components can avoid contamination of molded parts with lubricants, which, otherwise, may be required for proper operation of the injection mold in order to preserve the life of the injection mold components. In other words, incorporating PCD superhard material into the injection mold components may replace lubricants and may maintain the life and usefulness of the injection mold components. Lubricant-free operation may be particularly advantageous in molding medical products and/or components thereof (as well as other clean products and components), which may have more rigorous requirements of environment cleanliness than other molded products. 
     In one or more embodiments, the substrate may be omitted, and the injection mold components may include one or more layers of superhard materials such as cemented tungsten carbide or polycrystalline diamond. Also, the layer of superhard material (e.g., diamond) may be deposited, using chemical vapor deposition (CVD), physical vapor deposition, plasma-assisted chemical vapor deposition, or other deposition techniques. Example methods for depositing a superhard material are described in U.S. Pat. No. 7,134,868, the disclosure of which is incorporated by reference herein in its entirety. 
     The layer of superhard material may exhibit a substantially uniform thickness (i.e., with substantially uniform thickness) or a non-uniform thickness. Additionally or alternatively, the layer of superhard material may be continuous/contiguous or may be interrupted or formed from multiple segments. Furthermore, in some embodiments, a thickness of the layer of superhard material that forms a wear-resistant surface may be in the range of about 0.010 inches to about 0.200 inches. Additionally or alternatively, the thickness of the layer of superhard material may be in the range from about 0.020 inches to about 0.120 inches, about 0.040 inches to about 0.100 inches, and about 0.060 inches to about 0.090 inches. Moreover, the thickness of the superhard layer may be greater than about 0.200 inches. 
     In some embodiments, the superhard material may form more than one wear-resistant surface on a particular injection mold component. For example, as further described below, the superhard material may form two wear-resistant surfaces disposed at approximately 90° with respect to each other. Similarly, the superhard material may have one or more bonding surfaces. Furthermore, the boding surfaces also may be continuous or interrupted; for example, an entire surface of the superhard material may be bonded to the substrate or only a portion thereof. Hence, the superhard material may have more than one thickness measurements, depending on the number of bonding surfaces—e.g., the superhard material that has two bonding surfaces, and which forms two wear-resistant surfaces, may have two or more thickness measurements that correspond to the thicknesses between the respective bonding surfaces and a point on each of the wear-resistant surfaces. 
     The wear-resistant surface, formed by the superhard material, may have a reduced amount of wear from operation of the injection mold  120 , as compared to a surface that is not formed from superhard material. In some embodiments, the wear-resistant surface may at least in part for a surface of an injection mold component that contacts the molten molding material injected into the injection mold  120 . For example, such injection mold component may be the sprue bushing  150 , as illustrated in  FIGS. 3A-3C . The sprue bushing  150  may include a through-hole  151 , defined by inner wear-resistant surface  151   wr , which may allow the molten molding material to be injected from the injection molding machine  110  into the injection mold  120 . The sprue bushing  150  also may have a minor diameter  152 , a major diameter  153 , and a shoulder  154 , which may be formed between the minor and major diameters  152 ,  153 . One or more of the minor diameter  152 , the major diameter  153 , or the shoulder  154  may assist with locating the sprue bushing  150  in the injection mold  120 . 
     The sprue bushing  150  also may include a seal-off  155 , which may have a substantially hemispherical shape. Hence, the injection nozzle  117  of the injection molding machine  110  may press against the seal-off  155 , to create a sealed pathway for the molten molding material, from the injection system  114  into the injection mold  120 . As the material passes through the through-hole  151  of the sprue bushing  150 , the wear-resistant surface  151   wr  may provide an improved durability and wear resistance to the molten molding material, as compared to other materials. Similarly, repeated contact between the seal-off  155  and the injection nozzle  117  may wear or damage the surface of the seal-off  155 . 
     In one or more embodiments, the surface that defines the through-hole  151  may be at least partially formed by a wear-resistant surface  151   wr . In particular, a superhard material  150   sm  may form the wear-resistant surface  151   wr . Furthermore, the wear-resistant surface  151   wr  may span or cover only a portion of the through-hole  151  ( FIG. 3A ). In some embodiments, the superhard material  150   sm  that forms the wear-resistant surface  151   wr  may be disposed on an insert, which may be press-fitted into the sprue bushing  150 . Alternatively, the superhard material  150   sm  may be bonded to the sprue bushing  150  directly or through the substrate, as described above. 
     In at least one embodiment, the wear-resistant surface  151   wr  may span or cover the entire through-hole  151  ( FIGS. 3B and 3C ). Thus, in some embodiments, the wear-resistant surface  151   wr  may reduce wear (resulting from flow of molten molding material through the through-hole  151 ) on part of the through-hole  151  of the sprue bushing  150  ( FIG. 3A ). Alternatively, in other embodiments, the wear-resistant surface  151   wr  may reduce such wear along the entire surface of the through-hole  151  ( FIGS. 3B and 3C ). 
     Additionally or alternatively, the sprue bushing  150  also may have a wear-resistant surface  155   wr  disposed along the seal-off  155 . The wear-resistant surface  155   wr  may reduce the amount of wear associated with repeated contacts of the injection nozzle  117  with the seal-off  155 . Accordingly, the wear-resistant surface  155   wr  may extend life of the sprue bushing  150 . In some embodiments, at least a portion of the injection nozzle  117  may comprise superhard material. 
     The wear-resistant surface  155   wr  may cover the entire seal-off  155 . In other embodiments, the wear-resistant surface  155   wr  may cover only a portion of the seal-off  155 . Moreover, the same superhard material  150   sm  that may form the wear-resistant surface  151   wr  may also form the wear-resistant surface wear-resistant surface  155   wr . Alternatively, different separate bodies of superhard material may form the wear-resistant surfaces  151   wr  and  155   wr . Also, as described above, the superhard material  150   sm  may have varied and varying thicknesses. Furthermore, the superhard material  150   sm  also may cover a top of the sprue bushing  150 ; in other words, the superhard material  150   sm  may extend to the major diameter  153  of the sprue bushing  150  ( FIG. 3C ). 
     In some embodiments, as illustrated in  FIG. 3D , in lieu of or in addition to a sprue bushing, the manufacturer may use a hot runner system  180 , which may include a runner manifold  190  and one or more tip inserts  200 . The molten molding material may enter the hot runner system  180  through the sprue bushing. In some embodiments, the sprue bushing may incorporate one or more heating elements and may also include one or more wear-resistant surfaces, as described above. Alternatively, the injection nozzle  117  may seal off against the runner manifold  190  of the hot runner system  180 . Accordingly, the molten molding material from the injection molding machine  110  may directly enter the runner manifold  190  of the hot runner system  180  through the injection nozzle  117 . Generally, one or more embodiments may include one or more of the injection nozzles  117 , runner manifolds  190 , and tips inserts  200  comprising a superhard material. More particularly, any surface (or a portion thereof) of the injection nozzle injection nozzles  117 , runner manifolds  190 , and tips inserts  200  that contacts molten molding material may comprise a superhard material. 
     The hot runner system  180  may have one or more heater elements (not shown), which may help maintain the molding material in at least partially molten state within the hot runner system  180 . Similarly, the tip inserts  200  also may include heating elements  201  that may keep the molding material in at least partially molten state within the tip inserts  200 . The tip inserts  200  also may include an opening  202 , which may allow the molten molding material to flow into the molding volume  131  ( FIG. 1 ). In other words, the opening  202  may provide a channel for the molten molding material to flow from the runner manifold  190  of the hot runner system  180  into the molding volume  131 , defined by one or more molding elements  140  ( FIG. 1 ). 
     In some embodiments, the opening  202  may be at least partially defined by a wear-resistant surface  202   wr . As described above, a superhard material  200   sm  may form the wear-resistant surface  202   wr . Furthermore, the wear-resistant surface  202   wr  may span an entire length of the opening  202  or may only partially cover the surface of the opening  202 . For example, the wear-resistant surface  202   wr  may be disposed proximate to a connection point between the tip insert  200  and runner manifold  190  (i.e., proximate to the point where the molten molding material from the runner manifold  190  enters the tip insert  200 ). Alternatively, the wear-resistant surface  202   wr  may be disposed proximate a material exit point of the tip inserts  200  (i.e., proximate to the point where the material exits the tip insert  200  and enters the molding elements  140 . 
     Additionally, in at least one embodiment, the tip inserts  200  also may have an outer portion  203  that includes one or more wear-resistant surfaces  203   wr . For instance, the wear-resistant surface  203   wr  may be disposed proximate to an end (i.e., to the exit point) of the tip insert  200 . Moreover, the superhard material  200   sm  that forms the wear-resistant surface  202   wr  also may form the wear-resistant surfaces  203   wr . As described above, the superhard material  200   sm  that forms the wear-resistant surface  202   wr  and/or wear-resistant surfaces  203   wr  may be bonded to a substrate that is bonded to the tip inserts  200 , may be deposited onto a surface of the tip inserts  200 , and/or may form part of an insert that is bonded or mechanically secured to one or more of the tip inserts  200 . 
     In some instances, the part  130  ( FIG. 2 ) molded in the injection mold  120  may be direct-gated—i.e., a runner or the sprue bushing  150  may provide a direct pathway for the molten molding material into the molding volume  131 . Alternatively, the molding elements  140  may incorporate a tunnel gate  210 , illustrated in  FIG. 3E . Hence, a runner  212  may connect with the tunnel gate  210  and channel the molding material into the molding volume  131  ( FIG. 1 ). As described above, flow of the molten molding material may wear the surfaces of the  210  and/or runner  212 . Furthermore, as the injection mold  120  opens and/or as the part  130  is ejected from the molding element  140   a  or molding element  140   b , the molding material in the tunnel gate  210  may be sheared off by an edge  211  of the tunnel gate  210 . Thus, repetitive shearing of the molding material by the edge  211  of the tunnel gate  210  may wear, dull, and/or damage the edge  211 , which may result in subnormal damage to the final part  130 . 
     In at least one embodiment, the surface of the tunnel gate  210  may include a wear-resistant surface  210   wr , which may be formed by a superhard material  210   sm . The wear-resistant surface  210   wr  may cover the entire surface of the tunnel gate  210  or only a portion thereof. In some embodiments, the edge  211  of the tunnel gate  210  also may comprise superhard material. Moreover, the superhard material  210   sm  material that forms the wear-resistant surface  210   wr , also may form the edge  211  of the tunnel gate  210 . 
     Similar to the above-described superhard material, the superhard material  210   sm  forming the wear-resistant surface  210   wr  and/or the edge  211  of the tunnel gate  210  may be bonded to a substrate that is bonded to the injection mold component (e.g., to an injection mold plate and/or to one of the molding elements  140 ). The superhard material  210   sm  also may be bonded directly to the injection mold component. Alternatively, the tunnel gate  210 , at least partially, may be formed by a gate insert. Accordingly, the gate insert may incorporate the superhard material. In particular, the gate insert may comprise a substrate to which a superhard material may be bonded; the gate insert also may comprise steel or other metallic material to which the substrate with the superhard material  210   sm  may be bonded; or the gate insert may comprise steel or other metallic material and a bonded superhard material  210   sm.    
     In one or more embodiments, the injection mold  120  may include injection mold components that have surfaces in contact with other injection mold components (e.g., sliding surfaces that incorporate one or more wear-resistant surface formed by superhard material). For example, as illustrated in  FIGS. 4A and 4B , the locating ring  160  ( FIG. 2 ) may include a locating inside diameter  161  that may fit over the major diameter  153  of the sprue bushing  150 . Accordingly, the locating ring  160  may be aligned with the sprue bushing  150 . Hence, the locating ring  160  may be used to align the injection mold  120  within the injection molding machine  110 , such that the injection nozzle  117  of the injection molding machine  110  may substantially align with the sprue bushing  150 . 
     In particular, in one embodiment, the locating ring  160  may have an outside diameter  163  that may fit into an opening of substantially the same diameter in the front platen  111  of the injection molding machine  110 . Thus, a peripheral surface  162  of the locating ring  160  may contact the surface (or a portion thereof) of the corresponding opening in the front platen  111  of the injection molding machine  110 . In some embodiments, the surface defining the peripheral surface  162  may be formed as or may incorporate a wear-resistant surface  163   wr , which may be formed by superhard material  160   sm . Accordingly, the wear-resistant surface  163   wr  may have less wear and or deterioration from repeated contact with the corresponding opening in the front platen  111  (as compared with a steel surface forming the outside diameter  163 ). 
     Additionally, the surface of the locating inside diameter  161  of the locating ring  160  may contact the surface of the sprue bushing  150  that defines the major diameter  153 . In some embodiments, the surface of the locating inside diameter  161  may be formed as or may incorporate a wear-resistant surface  161   wr , which may be formed by one or more layers of superhard material  160   sm . Accordingly, the wear-resistant surface  161   wr  may exhibit reduced wear or deterioration. It should be noted that the same superhard material  160   sm  may form the wear-resistant surface  161   wr  and wear-resistant surface  163   wr.    
     In some instances, a surface of an injection mold component (sliding surface) may have relative sliding motion in contact with a surface of another injection mold component (stationary surface). In other words, the surface of a first injection mold component may slide in contact with the surface of a second injection mold component (one or both surfaces may be moving during such sliding motion). For example, as described above, the ejector pins  170  may be moved by the ejector plates  122   d  toward the front platen  111  of the injection molding machine  110 , thereby ejecting the part  130  out of the injection mold  120 . As the ejector pins  170  move, the outside surface of the ejector pins  170  (e.g., surface of the outside diameter of the ejector pins  170 ) may slide or contact with the surface of corresponding openings in the molding elements  140  (e.g., in the molding element  140   b ). 
     The contact between the opening and the ejector pins  170  may wear the ejector pins  170  and/or the openings in the molding elements  140 . Such wear may result in flashing—i.e., molten molding material flowing between the surfaces of the ejector pins  170  and the corresponding openings in the molding elements  140 . For instance, as illustrated in  FIGS. 2, 5A-5E , the molding elements  140  may incorporate an ejector sleeve  220  (e.g., ejector sleeves  220   a ,  220   b  shown in  FIG. 2 ), which may have one or more wear-resistant surfaces or surface segments. Such ejector sleeve  220  may be secured in one or more of the molding elements  140  (e.g., in the molding element  140   b ) and may, in part, form one or more surfaces of the molding elements  140  that at least in part defines the molding volume  131  ( FIG. 1 ). 
     The ejector pins  170  may pass through an opening  221  of the ejector sleeve  220  and eject the part  130 . Alternatively, the ejector sleeve  220  may be secured to the ejector plates  122   d  and the opening  221  may fit around a core pin (e.g., the core pin may be secured in the ejector housing  122   c ). Accordingly, in some embodiments, such ejector sleeve  220  also may, at least in part, move toward the front platen  111  of the injection molding machine  110  to eject the part  130 . In additional or alternative embodiments, the ejector pin  170  also may include a superhard material  170   sm . For example, a tip of the ejector pin  170  may incorporate superhard material  170   sm , which may form a wear-resistant surface  170   wr.    
     In one or more embodiments, the opening  221  may include a fitted portion  222  and a relieved portion  223 . The fitted portion  222  may have a close fit with the ejector pins  170  or with the core pin, as applicable. For instance, the ejector pin  170  may be a cylindrical pin. Hence, the opening  221  may have a substantially cylindrical shape. Furthermore, ejector sleeve  220  may have a clearance between the internal diameter of the opening  221  and the outside diameter of the ejector pin  170  in the range of about 0.01 mm to about 0.15 mm. The relieve portion  223  of the opening  221  may have a clearance that is greater than 0.15 mm between the internal diameter of the opening  221  and the outside diameter of the ejector pin  170 . 
     Whether stationary with respect to the ejector pins  170  (e.g., secured to the molding element  140   b ) or movable with respect to a core pin (e.g., secured in the ejector plates  122   d ), the ejector sleeve  220  may include a wear-resistant surface  221   wr , which may be formed by a superhard material  220   sm . The wear-resistant surface  221   wr  may extend along and cover the entire fitted portion  222  or a part of the fitted portion  222  of the opening  221 . The wear-resistant surface  221   wr  also may cover the entire relieved portion  223  or a part of the relieved portion  223  of the opening  221 . 
     Furthermore, the superhard material  220   sm  that forms the wear-resistant surface  221   wr  may have various thicknesses, as described above. For example, the superhard material  220   sm  may have a thickness that is less than the distance from the wear-resistant surface  221   wr  to an outer dimension of the ejector sleeve  220  (e.g., a thickness defined between the inside diameter of the opening  221  and an outside diameter  225  of the ejector sleeve  220 ). The superhard material  220   sm  may be bonded to the ejector sleeve  220  in the same manner as described above in connection with other injection mold components. 
     Additionally, as described above, a portion of the ejector sleeve  220  may form part of one or more molding elements  140 . In particular, a front face  224  of the ejector sleeve  220  may form part of the molding element  140   b , which may contact at least a portion of the part  130  ( FIG. 2 ). Thus, the front face  224  may experience wear caused by the flow of molten molding material in contact with the front face  224 . Accordingly, the ejector sleeve  220  also may include a wear-resistant surface  224   wr . The same superhard material  220   sm  that may form the wear-resistant surface  221   wr , also may form the wear-resistant surface  224   wr . The wear-resistant surface  224   wr  may cover all or a portion of the front face  224  of the ejector sleeve  220  and/or ejector pin  170 . 
     Additionally, as described above, thickness of the superhard material  220   sm  may vary, at least in part, based on the direction of the measurement. For instance, the thickness of the same superhard material  220   sm  may be measured from the wear-resistant surface  221   wr  as well as from wear-resistant surface  224   wr . Moreover, thickness of the superhard material  220   sm  may be measured only from one of the wear-resistant surfaces  221   wr ,  224   wr . More specifically, thickness of the superhard material  220   sm  (as measured from the wear-resistant surface  224   wr ) may be such as to cover part of the fitted portion  222  of the opening  221  ( FIG. 5B ). Alternatively, thickness of the superhard material  220   sm  may be such as to cover all of the fitted portion  222  and part of the relieved portion  223  of the opening  221  ( FIG. 5E ). 
     As described above, the ejector sleeve  220 , such as the ejector sleeve  220   b  ( FIG. 2 ) may move with respect to the core pin. In addition to contact that may occur between the ejector sleeve  220  and the core pin, the outside diameter  225  of the ejector sleeve  220  also may slide in contact with one or more molding elements  140  (e.g., within an opening of the molding element  140   b ). Accordingly, the surface formed by the outside diameter  225  of the ejector sleeve  220  may experience wear associated with such sliding. In at least one embodiment, a wear-resistant surface  225   wr , which may cover all or part of the surface formed by the outside diameter  225  of the ejector sleeve  220 , may reduce such wear ( FIGS. 5B and 5E ). Furthermore, the wear-resistant surface  225   wr  may be formed by the same body superhard material  220   sm  that may form the wear-resistant surface  221   wr  and/or wear-resistant surface  224   wr.    
     As described above, in some instances, the molding elements  140  may form or may have undercutting portions, such that the undercut must be relieved in order to eject the part  130  from the injection mold  120 . For example, as illustrated in  FIGS. 6A-6G , the injection mold  120  may include an undercut relief system  230 . In at least one embodiment, the undercut relief system  230  may include a slide body  240  and a heel lock  250 . The slide body  240  may secure one or more of the molding elements  140  (e.g., a core  140   d ). 
     The core  140   d  may form an undercutting portion of the part  130 . For example, the core  140   d  may form a hole or a ledge in the part  130 . Before ejecting the part  130 , the slide body  240  may move the core  140   d  out of the formed hole, thereby allowing the part  130  to be ejected. While the injection mold  120  is in the closed position, an angular portion  251  of the heel lock  250  may contact a corresponding angular portion  241  of the slide body  240 , which may aid in maintaining the slide body  240  in a desired position. 
     Accordingly, to relieve or release the undercutting portion, such as the core  140   d , when the injection mold  120  opens, an angle pin  260  may force the slide body  240  to move away from the part  130  (before the part  130  is ejected from the injection mold  120 ). More specifically, as the injection mold  120  opens, the moving portion  122  (which may include the second plate  122   a  and the support plate  122   b ) move away from the nonmoving portion  121  (which may include the first plate  121   a  and the top clamping plate  121   b ). The part  130  and the slide body  240  may remain on the moving portion  122 ; the slide body  240  may be restricted from movement away from the moving portion  122  by one or more gibs (not shown; see  FIG. 6B-6G ), which may guide the slide body  240 . The slide body  240  also may have a single degree of freedom of motion, to slide away from the part  130  (e.g., along the second plate  122   a ). Thus, as the slide body  240  moves away from the nonmoving portion  121 , which secures the angle pin  260 . Hence, as the slide body  240  moves with respect to the angle pin  260 , the slide body  240  is forced to slide away from the part  130 . 
     In at least one embodiment, the angular portion  241  of the slide body  240  may have a wear-resistant surface that covers the entire or a part of the angular portion  241 . For example, a superhard material  240   sm , as described above, may form all or part of the surface of the angular portion  241 . Accordingly, the surface of the angular portion  241  may have reduced wear (compared with another material, such as steel) from contact with the angular portion  251 . 
     Additionally or alternatively, the heel lock  250  also may incorporate a superhard material  250   sm , which may form a wear-resistant surface on at least a part of the surface of the angular portion  251 . In some embodiments, the wear-resistant surface of the angular portion  251  may have a lower hardness than the wear-resistant surface of the angular portion  241 . Alternatively, the wear-resistant surface of the angular portion  251  may have substantially the same or higher hardness than the wear-resistant surface of the angular portion  241 . 
     Furthermore, the angular portion  241  of the slide body  240  or the angular portion  251  of the heel lock  250  may at least partially incorporate a wearing surface. As used herein, the term “wearing” surface refers to a surface that comprises a material that is softer than the superhard material of the wear-resistant surface that is in contact with the wearing surface. Suitable materials for the wearing surface include steel, brass, bronze, copper alloys, aluminum alloys, polytetrafluoroethylene (PTFA), combinations thereof, or other suitable material. Accordingly, the wearing surface may aid in reducing the amount of wear experienced by the wear-resistant surface. For example, the wearing surface may comprise material that is softer than the superhard material that comprises the wear-resistant surface. Thus, a softer wearing surface may absorb more energy generated by friction at an interface between the wear-resistant surface and a contacting surface (e.g., the wearing surface) than by a harder contacting surface. In some embodiments, the wearing surface also may have a reduced coefficient of friction (as compare to other suitable materials). To illustrate, the angular portion  241  of the slide body  240  may include a wear-resistant surface comprising superhard material (as described above), and the angular portion  251  may have a wearing surface, which may wear more quickly or easily than the wear-resistant surface of the angular portion  241 , and which may increase the life of the wear-resistant surface of the angular portion  241 . 
     In some embodiments, the wearing surface may be removable and replaceable. For example, the wearing surface may comprise an insert that incorporates material that is softer than the wear-resistant surface that contacts the wearing surface. Hence, once the wearing surface has worn beyond an acceptable level, the insert comprising the wearing surface may be removed and replaced. 
     Furthermore, as the slide body  240  moves toward and away from the part  130  (or the molding elements  140  that at least in part form the part  130 ), the slide body  240  may be guided by one or more gibs  280  ( FIGS. 6B-6G ). One should note that, as described above in connection with  FIG. 6A , the cross-sectional view in  FIG. 6A  shows a cross-section that does not pass through the gibs  280 ; by contrast, cross-sectional views shown in  FIGS. 6B-6E  show a cross-section that is orthogonal to the cross-section shown in  FIG. 6A , and which passes through the gibs  280 . In particular, the gibs  280  may have one or more surfaces that may prevent the slide body  240  from lifting off from a surface upon which the slide body  240  slides (e.g., a slide surface  290 ). For instance, the gibs  280  may have one or more retaining surfaces  281  (see  FIG. 6F ), which may restrict lifting off of the slide body  240 . The slide body  240  also may have one or more shoulder surfaces  243 , which may interface (or interfere) with the retaining surfaces  281  of the gibs  280 . 
     Additionally or alternatively, the gibs  280  may have one or more surfaces that may control the direction of movement of the slide body  240 , and which may limit deviation of the slide body  240  from such direction. In particular, the gibs  280  may have one or more side surfaces  282 ,  283 , which may contact with one or more side surfaces  244 ,  245  of the slide body  240 . Accordingly, the side surfaces  244 ,  245  of the slide body  240  may move in sliding contact with the side surfaces  282 ,  283  of the gibs  280 , thereby guiding the slide body  240  along a desired path. 
     In one or more embodiments, one or more of the side surfaces  244 ,  245  may incorporate wear-resistant surfaces, which may cover the portion of side surfaces  244 ,  245  positioned within the gib  280   s  (e.g.,  FIG. 6D ). It should be noted that  FIG. 6D  illustrates different examples of wear-resistant surfaces on the slide body  240  and on the gibs  280 , which are shown differently on the left and the right sides of an assembly of the slide body  240  and gibs  280 . The wear-resistant surfaces also may cover only a portion of one or more of the side surfaces  244 ,  245  (e.g.,  FIGS. 6B, 6C, and 6E ). Accordingly, the side surfaces  244 ,  245  that incorporate, at least in part, the wear-resistant surfaces may experience reduced wear from the sliding in contact with the side surfaces  282  and/or  283  (as compared with a different material, such as steel). As described above, the wear-resistant surfaces incorporated into the side surfaces  244 ,  245  may be formed by a superhard material  240   sm , which may be bonded to the slide body  240  through a substrate, directly, or may form part of an insert secured to the slide body  240 . 
     Additionally or alternatively, the one or more of the side surfaces  282 ,  283  also may incorporate one or more wear-resistant surfaces, which may cover the side surfaces  282 ,  283  entirely or partially. In some embodiments, the wear-resistant surfaces formed on or incorporated into the side surfaces  282 ,  283  may have substantially the same hardness as the wear-resistant surface formed on or incorporated into the side surfaces  244 ,  245 . In other embodiments, the wear-resistant surfaces formed as or incorporated into the side surfaces  282 ,  283  may be softer than the wear-resistant surface formed as or incorporated into the side surfaces  244 ,  245 . Furthermore, the wear-resistant surfaces formed on or incorporated into the side surfaces  282 ,  283  also may be harder than the wear-resistant surface formed on or incorporated into the side surfaces  244 ,  245 . 
     Moreover, the one or more wear-resistant surfaces that form one or more of the side surfaces  244 ,  245  or the side surfaces  282 ,  283 , may be continuous or interrupted, as illustrated in  FIGS. 6B-6G . For instance, as the gibs  280  may have multiple wear-resistant surfaces  281   wr  and/or side surfaces  282   wr ,  283   wr  that may at least partially form the retaining surfaces  281  and/or side surfaces  282 ,  283 . In one or more embodiments, the wear-resistant surfaces  281   wr ,  282   wr ,  283   wr , or combinations thereof may comprise discrete surface segments, formed by multiple discrete layers or bodies of superhard material. Alternatively, the wear-resistant surfaces  281   wr ,  282   wr ,  283   wr , or combinations thereof may be formed by a single layer or body of superhard material that has variable thickness to form raised portions, forming the wear-resistant surfaces  281   wr ,  282   wr , and/or  283   wr.    
     In one or more embodiments, one or more of the side surfaces  282 ,  283  of the gibs  280  may incorporate or may be formed as wearing surfaces, which have a substantially lower hardness than the wear-resistant surfaces. Thus, one or more of the side surfaces  244 ,  245  that may be formed as or incorporate wear-resistant surfaces may experience further reduced wear. Alternatively, the side surfaces  244 ,  245  of the slide body  240  may be formed as or may incorporate wearing surfaces, which may come into contact with wear-resistant surfaces formed as or incorporated into the side surfaces  282 ,  283 . 
     Additionally or alternatively, the slide body  240  may have a bottom sliding surface  246 , which may slide in contact or across a top surface  291  of a slide plate  290 . The slide plate  290  may be incorporated into or secured to a plate comprising the nonmoving portion  121  or moving portion  122  of the injection mold  120 . The slide plate  290  also may be incorporated into or secured to one or more of the molding elements  140 . 
     The bottom sliding surface  246  of the slide body  240  may be formed as or may incorporate a wear-resistant surface  246   wr . Similar to the wear-resistant surfaces described above, the wear-resistant surface  246   wr  may be formed from a single body or multiple bodies or layers of superhard material. Moreover, the bottom sliding surface  246  may be continuous or interrupted, and the wear-resistant surface  246   wr  may cover the entire bottom sliding surface  246  or only a part of the bottom sliding surface  246  of the slide body  240  ( FIGS. 6B-6E ). 
     The top surface  291  of the slide plate  290  also may incorporate or may be formed as a wear-resistant surface (formed by a superhard material  290   sm ). In at least one embodiment, a wear-resistant surface  291   wr  may be incorporated into or may at least partially form the top surface  291  of the slide plate  290 . For example, the wear-resistant surface  291   wr  may cover the entire or only a portion of the top surface  291 . For example, the wear-resistant surface  291   wr  may comprise discrete surface segments ( FIG. 6G ). Alternatively, the wear-resistant surface  291   wr  may comprise a unitary on continuous surface, which may be substantially level or may have raised and/or lowered portions therein. 
     To move the slide body  240 , in some embodiments, the injection mold  120  may include the angle pin  260 , which may pull the slide body  240  away from the part  130  as the injection mold  120  opens ( FIG. 6A ). More specifically, the angle pin  260 , which may remain stationary while the moving portion  122  moves away from the nonmoving portion  121 , may guide the slide body  240  away from the part  130 , as the moving portion  122  (including the slide body  240 ) moves away from the nonmoving portion  121 . Alternatively, other mechanisms may be used to move the slide body  240  away from the part  130 . For instance, the slide body  240  may be moved by a cylinder (e.g., a hydraulic cylinder). Thus, as shown in  FIG. 6A , the slide body  240  may have the opening  242 , which may accommodate the angle pin  260  therein. 
     In at least one embodiment, the surface of the opening  242  and/or of the angle pin  260  may include a wear-resistant surface. For example, the wear-resistant surface may cover the entire or a part of the surface of the opening  242  in the slide body  240 . The wear-resistant surface of the opening  242  may reduce the amount of wear experienced by the opening  242  from repeated entry, exit, and/or sliding movement of the angle pin  260  against the surface of the opening  242  of the slide body  240 . The wear-resistant surface of the opening  242  may be formed by a superhard material  240   sm , which may be bonded to a substrate (such substrate may in turn be bonded to the slide body  240 ), to the slide body  240  directly, or may comprise an insert that is secured to the slide body  240 . 
     Additionally, the undercut relief system  230  also may include a slide retainer  270 , which may secure the slide body  240  (e.g., when the injection mold  120  is in the open position). For example, as illustrated in  FIGS. 7A and 7B , the slide retainer  270  may include a slide plate  271 , and a retention ball  272  and a spring  274  (i.e., a spring-loaded retention ball  272 ). As the slide body  240  moves away from the part  130  (or the corresponding molding elements  140  forming at least a portion of the part  130 ), the slide plate  271  moves past the spring loaded retention ball  272 . Once the spring loaded retention ball  272  reaches a detent  275  on the slide plate  271 , the retention ball  272  may maintain the slide plate  271  (and consequently the slide body  240 ) in a fixed position. 
     In some instances, movement of the retention ball  272  across (and in contact with) a bottom surface of the slide plate  271  may wear the bottom surface  273  of the slide plate  271 . In at least one embodiment, the bottom surface  273  of the slide plate  271  may include or may be formed by a wear-resistant surface formed by superhard material  270   sm . Furthermore, the wear-resistant surface may cover (or form) the entire or only a part of the bottom surface  273  of the slide plate  271 , as shown in  FIG. 7A . Also, superhard material  270   sm , which may form one or more wear-resistant surfaces, may be continuous across the entire bottom surface  273  of the slide plate  271  or may be interrupted. Moreover, as shown in  FIG. 7B , superhard material  270   sm  may comprise an insert, which may be secured to the slide body  240  (e.g., with mechanical fasteners such as screws or using bonding techniques, such as welding, brazing, etc.). In some embodiments, the insert may comprise the superhard material  270   sm  bonded to a substrate ( FIG. 7B ). Alternatively, the entire insert may comprise superhard material—i.e., the superhard material  270   sm  may be an insert secured to the slide body  240 . 
     As described above, the injection mold  120  may include one or more interlock pairs  280  ( FIG. 2 ). For example, as illustrated in  FIGS. 8A and 8B , the injection mold may include one or more rectangular two-plate interlock pairs  280   a  or interlock pairs having another suitable shape. More particularly, the rectangular single side interlock pair  280   a  comprise a male interlock  281   a  and a female interlock  282   a . The male interlock  281   a  may have a protrusion  283   a , which may enter and substantially align with a recess  284   a  within the female interlock  282   a . The protrusion  283   a  and/or the recess  284   a  may respectively incorporate superhard material  283   sm ,  284   sm . Accordingly, the protrusion and  283   a  and the recess  284   a  also may include wear resistant surfaces  283   wr ,  284   wr , respectively. 
     As described above, the interlock pair, such as the rectangular single side interlock pair  280   a  may include small clearance on each side, between the protrusion and the recess of the respective male and female interlock portions. For instance, such clearance may be in one of the following ranges 0.0002 inches to 0.0005 inches 0.0005 inches to 0.001 inches, and 0.001 inches to 0.005 inches. Thus, as the injection mold closes, sides of the protrusion and the recess may slide in contact one with the other. In particular, the wear-resistant surface  283   wr  may slide in contact with the wear-resistant surface  284   wr , as the protrusion  283   a  enters the recess  284   a.    
     In one or more embodiments, superhard material  283   sm  and  284   sm  may form the wear-resistant surfaces  283   wr ,  284   wr  that may define the entire surface of the protrusion and the recess (as shown in  FIGS. 8A and 8B ) or portions thereof. Additionally or alternatively, the superhard material  283   sm  may form wear-resistant surfaces  283   wr  only on the sides of the protrusion  283   a , as shown in  FIG. 8A . Similarly, the superhard material  284   sm  may form wear-resistant surface  284   wr  only on the sides of the recess  284 . 
     In additional or alternative embodiments, the superhard material  283   sm ,  284   sm , may form the entire protrusion  283  and recess  284 , as shown in  FIG. 8B . Thus, the superhard material  283   sm ,  284   sm  may form other wear-resistant surfaces, in addition to the side surfaces of the protrusion  283  and the recess  284 . For instance, the part material  284   sm  may form a bottom wear-resistant surface  284   wr  of the recess  284 . Furthermore, as described above, superhard material  283   sm ,  284   sm  may comprise one or more inserts, which may be secured within the male interlock  281   a  and/or the female interlock  282   a.    
     In at least one embodiment, the injection mold may include a three-plate interlock pair  280   b , as shown in  FIGS. 8C and 8D , which may align three plates of the injection mold. Accordingly, the three-plate interlock pair  280   b  may include a male interlock  281   b , which may enter into two opposing female interlocks  282   b . More specifically, the male interlock  281   b  may include two opposing protrusions  283   b , which may enter into recesses  284   b  of the female interlocks  282   b . Similar, as described above in connection with the rectangular two-plate interlock pairs  280   a  ( FIGS. 8A and 8B ), the three-plate interlock pair  280   b  may incorporate superhard material  283   sm ,  284   sm , which may form wear-resistant surfaces  283   wr ,  284   wr  of the protrusions  283  and recesses  284 , respectively. 
     Thus, the superhard material  283   sm ,  284   sm  may form wear-resistant surfaces  283   wr ,  284   wr  only on the respective sides of the protrusions  283  and recesses  284  that contact one another ( FIG. 8C ). Additionally or alternatively, the superhard material  283   sm ,  284   sm  also may form wear-resistant surfaces  283   wr ,  284   wr  on other sides and/or portions of the male and female interlocks  281 ,  282 . For instance, as shown in  FIG. 8D , the superhard material  283   sm ,  284   sm  may form the entire protrusion  283  and/or recess  284 , respectively. 
     The injection mold also may include tapered interlocks. For instance, as shown in  FIGS. 8E and 8F , the injection mold may incorporate one or more tapered interlock pairs  280   c . More specifically, the tapered interlock pair  280   c  may comprise a male interlock  281   c  and a corresponding female interlock  282   c . The male interlock  281   c  may include a tapered protrusion  283   c  that may enter a corresponding tapered recess  284   c  in the female interlock. In one or more embodiments, the tapered interlock pair  280   c  may include superhard material  283   sm ,  284   sm , which may form wear-resistant surfaces  283   wr ,  284   wr . Additionally, the superhard material  283   sm ,  284   sm  may form only the surfaces  283   wr ,  284   wr  of the respective protrusion  283   c  and recess  284   c  that may contact one another when the tapered interlock pair  280   c  closes, as described above (see also  FIG. 8E ). The superhard material  283   sm ,  284   sm  also may form the protrusion  283   c  and/or the recess  284   c  ( FIG. 8F ). 
     In further embodiments, the tapered interlock pair may be a cylindrical tapered interlock pair  280   d , as shown in  FIGS. 8G and 8H . Similarly, the cylindrical tapered interlock pair  280   d  may comprise a male and female interlocks  281   d ,  282   d , which may have a corresponding protrusion  283   d  and recess  284   d . Also, the protrusion  283  and recess  284  may include superhard material  283   sm ,  284   sm , respectively, which may form wear-resistant surfaces  283   wr ,  284   wr . As described above, the wear-resistant surfaces  283   wr ,  284   wr  may form only the one or more surfaces of the respective protrusion and recess  283 ,  284  that may contact one another when the cylindrical tapered interlock pair  280   d  closes ( FIG. 8G ). Additionally or alternatively, the superhard material  283   sm ,  284   sm  may form the respective protrusion and/or recess  283 ,  284  ( FIG. 8H ). 
     While various aspects and embodiments have been disclosed herein, other aspects and embodiments are contemplated. The various aspects and embodiments disclosed herein are for purposes of illustration and are not intended to be limiting. Additionally, the words “including,” “having,” and variants thereof (e.g., “includes” and “has”) as used herein, including the claims, shall be open ended and have the same meaning as the word “comprising” and variants thereof (e.g., “comprise” and “comprises”).