Patent Publication Number: US-11642720-B2

Title: Integral core bumpers

Description:
FIELD 
     The present disclosure relates to airfoils for gas turbine engines, and in particular, to ceramic cores having integral bumpers. 
     BACKGROUND 
     In gas turbine engines, airfoils, such as rotor blades and stator vanes may include internal cavities in which cooling air is introduced to convectively cool the airfoil. Internal cavities may be formed by a ceramic core during the manufacturing process for airfoils. Bumpers can be added to ceramic cores to keep the ceramic core centered in a casting during manufacturing. 
     SUMMARY 
     A casting core assembly is disclosed herein. The casting core assembly may comprise: a casting core having an outer surface; a bumper disposed on the outer surface, the bumper comprising a receptacle; and a metal apparatus partially disposed in the receptacle of the bumper, a portion of the metal apparatus extending outward from the bumper. 
     In various embodiments, the metal apparatus is a pin. The pin may comprise a proximal end and a distal end disposed opposite the proximal end, and wherein the proximal end is disposed at a depth below the outer surface of the casting core. The metal apparatus may be a sphere. The bumper may be integral to the casting core. The metal apparatus may be coupled to the bumper by at least one of an adhesive or a mechanical lock. The metal apparatus may be configured to merge into an airfoil casting. 
     A method of manufacturing a casting assembly is disclosed herein. The method may comprise: forming a casting core having an outer surface; inserting a pin into the outer surface of the casting core; injecting ceramic composite around the pin; and heating the casting core, the injected ceramic composite and the pin. 
     In various embodiments, heating the casting core may further comprise forming a casting core assembly including a bumper assembly. The method may further comprise: injecting a wax around the casting core and the bumper assembly. The wax may enclose the bumper assembly. The method may further comprise forming an external shell around the wax. The forming the external shell may further comprise dipping the wax into a ceramic matrix slurry. The method may further comprise heating the casting assembly and removing the wax from the casting assembly. 
     A method of manufacturing a casting assembly is disclosed herein. The method may comprise: forming a casting core having a bumper disposed on an outer surface of the casting core, the bumper comprising a receptacle; inserting a metal apparatus into the receptacle of the bumper; and coupling the metal apparatus to the bumper. 
     In various embodiments, the coupling the metal apparatus is via at least one of a mechanical lock and an adhesive. The method may further comprise injecting wax around the casting core, the bumper, and the metal apparatus. The method may further comprise forming an external shell around the injected wax. The method may further comprise heating the casting assembly. The metal apparatus may be selected from a group consisting of a pin and a sphere. 
     The foregoing features and elements may be combined in various combinations without exclusivity, unless expressly indicated otherwise. These features and elements as well as the operation thereof will become more apparent in light of the following description and the accompanying drawings. It should be understood, however, the following description and drawings are intended to be exemplary in nature and non-limiting. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The subject matter of the present disclosure is particularly pointed out and distinctly claimed in the concluding portion of the specification. A more complete understanding of the present disclosure, however, may best be obtained by referring to the detailed description and claims when considered in connection with the figures, wherein like numerals denote like elements. 
         FIG.  1    illustrates an exemplary gas turbine engine, in accordance with various embodiments; 
         FIG.  2    illustrates an exemplary air foil having an internal cooling passage, in accordance with various embodiments; 
         FIG.  3    illustrates a cast core for casting an airfoil, in accordance with various embodiments; 
         FIG.  4    illustrates a cast core including a bumper assembly, in accordance with various embodiments; 
         FIG.  5 A  illustrates a cross-sectional view of a casting assembly prior to casting, in accordance with various embodiments; 
         FIG.  5 B  illustrates a cross-sectional view of a casting assembly after wax removal and prior to casting, in accordance with various embodiments; 
         FIG.  6    illustrates a cast core including a bumper assembly, in accordance with various embodiments; 
         FIG.  7 A  illustrates a cross-sectional view of a casting assembly prior to casting, in accordance with various embodiments; 
         FIG.  7 B  illustrates a cross-sectional view of a casting assembly after wax removal and prior to casting, in accordance with various embodiments; 
         FIG.  8    illustrates a method of manufacturing a cast core assembly, in accordance with various embodiments; and 
         FIG.  9    illustrates a method of manufacturing a cast core assembly, in accordance with various embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     All ranges and ratio limits disclosed herein may be combined. It is to be understood that unless specifically stated otherwise, references to “a,” “an,” and/or “the” may include one or more than one and that reference to an item in the singular may also include the item in the plural. 
     The detailed description of various embodiments herein makes reference to the accompanying drawings, which show various embodiments by way of illustration. While these various embodiments are described in sufficient detail to enable those skilled in the art to practice the disclosure, it should be understood that other embodiments may be realized and that logical, chemical, and mechanical changes may be made without departing from the spirit and scope of the disclosure. Thus, the detailed description herein is presented for purposes of illustration only and not of limitation. For example, the steps recited in any of the method or process descriptions may be executed in any order and are not necessarily limited to the order presented. Furthermore, any reference to singular includes plural embodiments, and any reference to more than one component or step may include a singular embodiment or step. Also, any reference to attached, fixed, connected, or the like may include permanent, removable, temporary, partial, full, and/or any other possible attachment option. Any reference related to fluidic coupling to serve as a conduit for cooling airflow and the like may include permanent, removable, temporary, partial, full, and/or any other possible attachment option. Additionally, any reference to without contact (or similar phrases) may also include reduced contact or minimal contact. Cross hatching lines may be used throughout the figures to denote different parts but not necessarily to denote the same or different materials. 
     As used herein, “aft” refers to the direction associated with the exhaust (e.g., the back end) of a gas turbine engine. As used herein, “forward” refers to the direction associated with the intake (e.g., the front end) of a gas turbine engine. 
     A first component that is “radially outward” of a second component means that the first component is positioned at a greater distance away from the engine central longitudinal axis than the second component. A first component that is “radially inward” of a second component means that the first component is positioned closer to the engine central longitudinal axis than the second component. In the case of components that rotate circumferentially about the engine central longitudinal axis, a first component that is radially inward of a second component rotates through a circumferentially shorter path than the second component. The terminology “radially outward” and “radially inward” may also be used relative to references other than the engine central longitudinal axis. A first component that is “radially outward” of a second component means that the first component is positioned at a greater distance away from the engine central longitudinal axis than the second component. As used herein, “distal” refers to the direction outward, or generally, away from a reference component. As used herein, “proximal” refers to a direction inward, or generally, towards the reference component. 
     The next generation turbofan engines are designed for higher efficiency and use higher pressure ratios and higher temperatures in the high pressure compressor than are conventionally experienced. These higher operating temperatures and pressure ratios create operating environments that cause thermal loads that are higher than the thermal loads conventionally experienced, which may shorten the operational life of current components. 
     The present disclosure relates to casting core assemblies. Casting core assemblies may comprise a casting core and a bumper assembly. The bumper assembly may comprise a bumper and a metal apparatus. The bumper extends from an outer surface of the casting core and may be integral to the casting core. The bumper may comprise a receptacle. The metal apparatus may be disposed within the receptacle of the bumper. The metal apparatus may be coupled to the bumper while the casting core is being formed or the casting core assembly may be formed and the metal apparatus may be coupled to the receptacle via an adhesive or a mechanical lock. The casting core assembly may eliminate the hand work of inserting a metal apparatus into wax patterns and blending them off post cast. The bumper assembly may allow repeatable positioning of an airfoil because it&#39;s a component of the casting core assembly. The bumper assembly may eliminate holes produced through an airfoil and/or between ribs during casting. 
     Referring now to  FIG.  1   , an exemplary gas turbine engine  20  is shown, in accordance with various embodiments. Gas turbine engine  20  may be a two-spool turbofan that generally incorporates a fan section  22 , a compressor section  24 , a combustor section  26  and a turbine section  28 . In operation, fan section  22  can drive coolant (e.g., air) along a bypass-flow path B while compressor section  24  can drive coolant along a core-flow path C for compression and communication into combustor section  26  then expansion through turbine section  28 . Although depicted as a turbofan gas turbine engine  20  herein, it should be understood that the concepts described herein are not limited to use with turbofans as the teachings may be applied to other types of turbine engines including three-spool architectures. 
     Gas turbine engine  20  may generally comprise a low speed spool  30  and a high speed spool  32  mounted for rotation about an engine central longitudinal axis A-A′ relative to an engine static structure  36  via several bearing systems  38 ,  38 - 1 , and  38 - 2 . It should be understood that various bearing systems  38  at various locations may alternatively or additionally be provided, including for example, bearing system  38 , bearing system  38 - 1 , and bearing system  38 - 2 . 
     Low speed spool  30  may generally comprise an inner shaft  40  that interconnects a fan  42 , a low-pressure compressor  44  and a low-pressure turbine  46 . Inner shaft  40  may be connected to fan  42  through a geared architecture  48  that can drive fan  42  at a lower speed than low speed spool  30 . Geared architecture  48  may comprise a gear assembly  60  enclosed within a gear housing  62 . Gear assembly  60  couples inner shaft  40  to a rotating fan structure. High speed spool  32  may comprise an outer shaft  50  that interconnects a high-pressure compressor  52  and high-pressure turbine  54 . Airfoils  55  coupled to a rotor of high-pressure turbine may rotate about the engine central longitudinal axis A-A′ or airfoils  55  coupled to a stator may be rotationally fixed about engine central longitudinal axis A-A′. 
     A combustor  56  may be located between high-pressure compressor  52  and high-pressure turbine  54 . Mid-turbine frame  57  may support one or more bearing systems  38  in turbine section  28 . Inner shaft  40  and outer shaft  50  may be concentric and rotate via bearing systems  38  about the engine central longitudinal axis A-A′, which is collinear with their longitudinal axes. As used herein, a “high-pressure” compressor or turbine experiences a higher pressure than a corresponding “low-pressure” compressor or turbine. 
     The core airflow along core-flow path C may be compressed by low-pressure compressor  44  then high-pressure compressor  52 , mixed and burned with fuel in combustor  56 , then expanded over high-pressure turbine  54  and low-pressure turbine  46 . Mid-turbine frame  57  includes airfoils  59 , which are in the core airflow path. Turbines  46 ,  54  rotationally drive the respective low speed spool  30  and high speed spool  32  in response to the expansion. 
     Gas turbine engine  20  may be, for example, a high-bypass ratio geared aircraft engine. In various embodiments, the bypass ratio of gas turbine engine  20  may be greater than about six (6). In various embodiments, the bypass ratio of gas turbine engine  20  may be greater than ten (10). In various embodiments, geared architecture  48  may be an epicyclic gear train, such as a star gear system (sun gear in meshing engagement with a plurality of star gears supported by a carrier and in meshing engagement with a ring gear) or other gear system. Geared architecture  48  may have a gear reduction ratio of greater than about 2.3 and low-pressure turbine  46  may have a pressure ratio that is greater than about five (5). In various embodiments, the bypass ratio of gas turbine engine  20  is greater than about ten (10:1). In various embodiments, the diameter of fan  42  may be significantly larger than that of the low-pressure compressor  44 . Low-pressure turbine  46  pressure ratio may be measured prior to inlet of low-pressure turbine  46  as related to the pressure at the outlet of low-pressure turbine  46  prior to an exhaust nozzle. It should be understood, however, that the above parameters are exemplary of various embodiments of a suitable geared architecture engine and that the present disclosure contemplates other turbine engines including direct drive turbofans. 
     Airfoil  55  may be an internally cooled component of gas turbine engine  20 . Trip strips may be located in internal cooling cavities of internally cooled engine parts. Internally cooled engine parts may be discussed in the present disclosure in terms of airfoils. However, the present disclosure applies to any internally cooled engine component (e.g., blade outer air seals, airfoil platforms, combustor liners, blades, vanes, or any other internally cooled component in a gas turbine engine). 
     With reference to  FIG.  2   , an airfoil  100  is shown with cooling passage  108 , in accordance with various embodiments. Although an airfoil is shown, the present disclosure applies to any internally cooled part (e.g., blade outer air seals, airfoil platforms, combustor components, etc.). Airfoil  100  has a pressure side  102 , a leading edge  104 , and a trailing edge  106 . Airfoil  100  also includes top  111  and suction side  113 . Pressure side  102  surface is partially cutaway to illustrate cooling passages  108  defined be internal walls of airfoil  100 . Hot air flowing through a gas turbine engine may first contact leading edge  104 , flow along pressure side  109  and/or suction side  113  and leave airfoil at trailing edge  106 . 
     In various embodiments, material  107  may define internal passages such as cooling passage  108 . Cooling passage  108  is oriented generally in a direction from platform  112  and attachment  114  towards top  111  (i.e., a radial direction when airfoil  100  is installed in a turbine). Airfoil  100  may contain multiple cooling passages or chambers similar to cooling passage  108  oriented in various directions with varying hydraulic diameters. The internal cooling passages may be interconnected. Multiple cooling features may appear in the internal cooling passages, as illustrated in further detail below. 
     With reference to  FIG.  3   , a cast core  200 , in accordance with various embodiments, is illustrated. Cast core  200  may be used in casting airfoil  100  to define internal features. Cast core  200  may define features aft of leading edge  104  and up to trailing edge  106  in airfoil  100 . Cast core  200  may extend beyond trailing edge  106  of airfoil  100  during the casting process to define aft cooling openings. Cast core  200  may define cooling passage  108  of airfoil  100  and cooling features therein. In that regard, both airfoil  100  and cast core  200  may have the cooling passages and cooling features described herein. 
     The features of cast core  200  may be negatives of the cooling features described below with respect to an airfoil  100 . Stated another way, cavities, openings, passages, and the like of airfoil  100  may be defined by material in cast core  200 . Cooling features and pedestals of airfoil  100  that are defined by material in airfoil  100  as described herein may be formed as passages and openings in cast core  200 . Thus, the features described below as bumpers and cooling passages may describe the structure of an airfoil  100  and/or a cast core  200 . 
     Cast core  200  may be placed in a mold, and the material to form a component (e.g., airfoil  100 ) may be deposited in the mold. Cast core  200  may be removed from the component, leaving cavities and the desired cooling features in the component. Airfoil  100  (as well as other components using fluid turbulation) may be made from an austenitic nickel-chromium-based alloy such as that sold under the trademark Inconel® which is available from Special Metals Corporation of New Hartford, N.Y., USA, or other materials capable of withstanding exhaust temperatures. 
     With reference to  FIG.  4   , a cast core  200  including a bumper assembly  300 , in accordance with various embodiments, is illustrated. Cast core  200  comprises an outer surface  202  and a bumper assembly  300  extending outward from outer surface  202 . In various embodiments, bumper assembly  300  is integral to the cast core  200 . Bumper assembly  300  comprises a bumper  310  and a pin  320 . The pin  320  may be disposed partially within the bumper  310 . 
     In various embodiments, the bumper  310  comprises a fillet  312  coupling a proximal edge  313  of bumper  310  to the outer surface  202  of the cast core  200 . The fillet  312  may reduce stress concentrations during the casting process. In various embodiments, bumper  310  is a truncated cone  314  extending from proximal edge  313  to distal edge  315 . The bumper  310  further comprises a receptacle  316  extending from distal edge  315  into the cast core  200 . Receptacle  316  may be a recess and may comprise a cylindrical shape. In various embodiments, the receptacle  316  may have a depth past outer surface  202  of the cast core  200 . In various embodiments, the bumper  310  is integral to the cast core  200 . The bumper may be made from ceramic composite, or any other material known in the art. Similarly, the cast core may be made from ceramic composite, or any other material known in the art. 
     The pin  320  may comprise a proximal end  322  and a distal end  324 . In various embodiments, proximal end  322  is disposed within, and surrounded by, receptacle  316  of bumper  310 . In various embodiments, distal end  324  of pin  320  may be at a first height measured perpendicular to outer surface  202  of the cast core  200  that is greater than a second height of the bumper  310 . In various embodiments, pin  320  is made from any metal alloy known in the art, such as platinum, or the like. In various embodiments, pin  320  is cylindrical in shape. 
     In various embodiments, pin  320  may be coupled to bumper  310  by inserting the pin  320  into cast core  200  to a depth below outer surface  202 . Next, bumper  310  may be injected partially around the pin  320  to form receptacle  316  and capture the pin  320  within bumper  310 . The bumper  310  may then be hardened with the cast core  200  to couple the pin  320  and the bumper  310  to the cast core  200 . In various embodiments, bumper  310  may be integral to cast core  200 . The bumper  310  may comprise the receptacle  316 . The pin  320  may be inserted into the receptacle  316  and coupled via an adhesive or a mechanical lock. By integrating the pin  320  into the cast core  200 , the manual process of inserting a pin into a wax pattern and blending the pin  320  off post casting may be eliminated. 
     With reference to  FIG.  5 A , a cross-sectional view of a casting assembly  400  prior to casting, in accordance with various embodiments, is illustrated. In various embodiments, the casting assembly  400  comprises an external shell  410 , a core assembly  420 , and wax  430  disposed between the core assembly  420  and the external shell  410 . In various embodiments, external shell  410  comprises an outer surface  412  and an inner surface  414  disposed opposite the outer surface. In various embodiments, casting assembly  400  comprises a cast core  200  and a bumper assembly  300 . In various embodiments, distal end  324  of pin  320  is disposed between 0.000 inches and 0.006 inches (0.000 cm and 0.015 cm) from inner surface  414  of external shell  410 , or between 0.002 inches and 0.006 inches (0.005 cm and 0.015 cm), or between 0.003 inches and 0.005 inches (0.008 cm and 0.013 cm). In various embodiments, distal end  324  of pin  320  contacts inner surface  414  of external shell  410 . 
     In various embodiments, the external shell  410  is made of ceramic composite, or any other material known in the art. In various embodiments, the core assembly  420  is manufactured. Then, the core assembly  420  is placed into a wax die. Wax  430  is then injected around the core assembly  420 . The external pattern of airfoil  100  is produced by the injected wax  430 . The mold assembly comprising the core assembly  420  and the wax  430  is then placed on a tree assembly. The tree assembly is then dipped into ceramic to make external shell  410  outside of the wax  430  and resulting in casting assembly  400 . Next, the casting assembly  400  is heated and the wax  430  is melted and removed from the casting assembly  400  resulting in casting assembly  401 , as shown in  FIG.  5 B . 
     In various embodiments, with reference to  FIG.  5 B , after the wax  430  has been removed from the casting assembly, distal end  324  of pin  320  may abut external shell  410 . During casting, a metal alloy is dispersed through the space between the inner surface  414  of external shell  410  and core assembly  420 . The bumper assembly  300  may allow repeatable positioning on an airfoil  100  (from  FIG.  2   ), since the pin  320  may merge into the finished casting of the airfoil  100  and/or may eliminate a hole through the airfoil  100  and/or between ribs of the airfoil  100 . 
     With reference to  FIG.  6   , a cast core  500  including a bumper assembly  505 , in accordance with various embodiments, is illustrated. Cast core  500  comprises an outer surface  502  and a bumper assembly  505  extending outward from outer surface  502 . In various embodiments, bumper assembly  505  is integral to the cast core  500 . Bumper assembly  505  comprises a bumper  510  and a sphere  520 . The sphere  520  may be disposed partially within the bumper  310 . Although depicted as a sphere  520  in  FIG.  6   , and a pin  320  in  FIGS.  4  and  5   , any metallic apparatus partially disposed in a bumper of a cast core and protruding away from the bumper of the cast core is within the scope of this disclosure. 
     In various embodiments, the bumper  510  comprises a fillet  512  coupling a proximal edge  513  of bumper  510  to the outer surface  502  of the cast core  500 . The fillet  512  may reduce stress concentrations during the casting process. In various embodiments, bumper  510  is a truncated cone  514  extending from proximal edge  513  to distal edge  515 . The bumper  510  further comprises a receptacle  516  extending from distal edge  515  into the bumper  510 . Receptacle  516  may be a recess and may comprise a semi-spherical shape. In various embodiments, the receptacle  516  may have a depth less than a height measured perpendicular to outer surface  502  from outer surface  502  to distal edge  515 . In various embodiments, the bumper  510  is integral to the cast core  500 . The bumper may be made from ceramic composite, or any other material known in the art. Similarly, the cast core may be made from ceramic composite, or any other material known in the art. 
     In various embodiments, the bumper  510  may comprise the receptacle  516 . The sphere  520  may be inserted into the receptacle  516  and coupled via an adhesive or a mechanical lock. By integrating the sphere  520  into a bumper assembly  505  of a cast core  500 , the manual process of inserting a pin into a wax pattern and blending the pin off post casting may be eliminated. 
     With reference to  FIG.  7 A , a cross-sectional view of a casting assembly  600  prior to casting, in accordance with various embodiments, is illustrated. In various embodiments, the casting assembly  600  comprises an external shell  610 , a core assembly  620 , and a wax disposed between the core assembly  620  and the external shell  610 . In various embodiments, external shell  610  comprises an outer surface  612  and an inner surface  614  disposed opposite the outer surface  612 . In various embodiments, casting assembly  600  comprises a casting core  500  and a bumper assembly  505 . In various embodiments, a distal end  524  of sphere  520  between 0.000 inches and 0.006 inches (0.000 cm and 0.015 cm) from inner surface  614  of external shell  610 , or between 0.002 inches and 0.006 inches (0.005 cm and 0.015 cm), or between 0.003 inches and 0.005 inches (0.008 cm and 0.013 cm). In various embodiments, distal end  524  of sphere  520  contacts inner surface  614 . In various embodiments, 25%-75% of a surface area of sphere  520  is disposed within receptacle  516  of bumper  510 , or between 35% and 65% of the surface area, or between 40% and 60% of the surface area. 
     In various embodiments, the external shell  610  is made of ceramic composite, or any other material known in the art. In various embodiments, the core assembly  620  is manufactured. Then, the core assembly  620  is placed into a wax die. Wax  630  is then injected around the core assembly  620 . The external pattern of airfoil  100  (from  FIG.  2   ) is produced by the injected wax  630 . The mold assembly comprising the core assembly  620  and the wax  630  is then placed on a tree assembly. The tree assembly is then dipped into ceramic to make external shell  610  outside of the wax  630  and resulting in casting assembly  600 . Next, the casting assembly  600  is heated and the wax  630  is melted and removed from the casting assembly  600  resulting in casting assembly  601 , as shown in  FIG.  7 B . 
     In various embodiments, with reference to  FIG.  5 B , after the wax  630  has been removed from the casting assembly, distal end  524  of sphere  520  may abut external shell  610 . During casting, a metal alloy is dispersed through the space between the inner surface  614  of external shell  610  and core assembly  620 . The bumper assembly  505  may allow repeatable positioning on an airfoil  100  (from  FIG.  2   ), since the sphere  520  may merge into a finished casting of the airfoil  100  and/or may eliminate a hole through the airfoil  100  and/or between ribs of the airfoil  100 . 
     With reference now to  FIG.  8   , a method of manufacturing a casting core assembly, in accordance with various embodiments, is illustrated. The method comprises forming a casting core having an outer surface (step  802 ). The casting core may be made of a ceramic matrix, or any other material known in the art. Next, a pin may be inserted into the outer surface of the casting core (step  804 ). A ceramic composite may be injected around the pin and form a bumper assembly on the outer surface of the casting core (step  806 ). In various embodiments, the casting core assembly may be as illustrated in  FIGS.  4  and  5   . Next, the casting core assembly may be heated forming a solid casting core assembly that couples the pin to the casting core assembly (step  808 ). Then, the casting core assembly may be placed in a wax die and wax may be injected around the casting core assembly (step  810 ). In various embodiments, the wax may enclose the bumper assembly within it. 
     In various embodiments, the method may further comprise forming an external shell around the injected wax (step  812 ). Forming the external shell may be done by placing the casting core assembly and wax on a mold with a tree assembly and dipping the casting core assembly and wax into a ceramic matrix slurry. The ceramic matrix slurry may be heated to harden the external shell resulting in a casting assembly as illustrated in  FIG.  5 A . In various embodiments, the method further comprises heating the casting assembly (step  814 ). Next, the wax may be removed as it becomes liquified during step  814  (step  816 ). In various embodiments, the casting assembly from  FIG.  5 B  may be produced by step  816 . 
     With reference now to  FIG.  9   , a method of manufacturing a casting core assembly, in accordance with various embodiments, is illustrated. The method comprises forming a casting core having a bumper disposed on an outer surface (step  902 ). In various embodiments, the bumper may be in accordance with  FIGS.  4 - 7 B . The bumper may comprise a truncated cone and a receptacle disposed at an outer surface of the truncated cone. The casting core and bumper may be made of a ceramic matrix, or any other material known in the art. The method further comprises inserting a metal apparatus into the receptacle of the bumper (step  904 ). The metal apparatus may be a pin, a sphere, or any other metal apparatus known in the art. In various embodiments, the metal apparatus is made of platinum. The method may further comprise coupling the metal apparatus to the bumper (step  906 ). The metal apparatus may be coupled to the bumper by an adhesive and/or a mechanical lock. After the metal apparatus is coupled to the bumper a casting core assembly, as illustrated in  FIGS.  4 - 7 B  may be formed. The method further comprises injecting wax around the casting core and bumper assembly (step  908 ). This may be done by placing the casting core assembly in a wax die injecting the wax around the casting core assembly. In various embodiments, the wax may enclose the bumper assembly within it. 
     In various embodiments, the method may further comprise forming an external shell around the injected wax (step  912 ). Forming the external shell may be done by placing the casting core assembly and wax on a mold with a tree assembly and dipping the casting core assembly and wax into a ceramic matrix slurry. The ceramic matrix slurry may be heated to harden the external shell resulting in a casting assembly as illustrated in  FIG.  5 A  of  FIG.  7 A . In various embodiments, the method further comprises heating the casting assembly (step  914 ). Next, the wax may be removed as it becomes liquified during step  914  (step  916 ). In various embodiments, the casting assembly from  FIG.  5 B  may be produced by step  916 . 
     Benefits and other advantages have been described herein with regard to specific embodiments. Furthermore, the connecting lines shown in the various figures contained herein are intended to represent exemplary functional relationships and/or physical couplings between the various elements. It should be noted that many alternative or additional functional relationships or physical connections may be present in a practical system. However, the benefits, advantages, and any elements that may cause any benefit or advantage to occur or become more pronounced are not to be construed as critical, required, or essential features or elements of the disclosure. The scope of the disclosure is accordingly to be limited by nothing other than the appended claims, in which reference to an element in the singular is not intended to mean “one and only one” unless explicitly so stated, but rather “one or more.” Moreover, where a phrase similar to “at least one of A, B, or C” is used in the claims, it is intended that the phrase be interpreted to mean that A alone may be present in an embodiment, B alone may be present in an embodiment, C alone may be present in an embodiment, or that any combination of the elements A, B and C may be present in a single embodiment; for example, A and B, A and C, B and C, or A and B and C. 
     Systems, methods and apparatus are provided herein. In the detailed description herein, references to “various embodiments”, “one embodiment”, “an embodiment”, “an example embodiment”, etc., indicate that the embodiment described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described. After reading the description, it will be apparent to one skilled in the relevant art(s) how to implement the disclosure in alternative embodiments. 
     Furthermore, no element, component, or method step in the present disclosure is intended to be dedicated to the public regardless of whether the element, component, or method step is explicitly recited in the claims. No claim element is intended to invoke 35 U.S.C. 112(f) unless the element is expressly recited using the phrase “means for.” As used herein, the terms “comprises”, “comprising”, or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.