Glass device for changing the apparent density in a metal casting

Abstract

A casting system includes a casting for an automobile, the casting having an interior section. A plurality of center portions are each positioned in one of a plurality of regions of the interior section, the interior section being completely encased by metal of the casting. An insert member is positioned in each of the plurality of center portions, the insert member having a melting point that is higher than a melting point of the metal of the casting that the insert member displaces.

Description

Technical Field

[0001] This disclosure relates to metal casting, particularly the casting of aluminum components. Background Technology

[0002] In automotive component casting, casting molds filled with sand are typically produced to create the geometry of the cast parts. After the casting operation is complete, it is often difficult to remove all the sand from the as-cast parts, especially for parts with complex geometries, such as automotive cast wheels or aluminum cast wheels. Therefore, casting sand removal paths are incorporated where possible to make sand removal more reproducible. However, sand casting is not a viable option for locations within as-cast parts with complex geometries where no path for sand removal is available after casting. Therefore, alternative casting processes are desired.

[0003] It is also desirable to reduce or minimize the overall volume and weight of casting materials such as aluminum to reduce the weight and cost of cast parts without compromising their strength. It has been found that placing voids within cast parts can save weight and cost; however, voids left within cast parts can create stress zones in the finished parts under load.

[0004] Therefore, although current automotive casting systems achieve their intended purpose, new and improved metal casting systems are still needed. Summary of the Invention

[0005] According to several aspects, the casting system includes a casting for an automobile, the casting having an internal section. Multiple central portions are each positioned in one of multiple regions within the internal section, the internal section being completely enclosed by the metal of the casting. Insert members are positioned in various portions of the multiple central portions. The melting point of the insert member is higher than the melting point of the metal of the casting that the insert member displaces.

[0006] In another aspect of this disclosure, the insert defines a glass material, and the casting defines a casting wheel.

[0007] In another aspect of this disclosure, the insert member includes a length that maximizes the volume of the plurality of central portions; and the insert member is spaced inwardly from the raised edge of the casting wheel by a distance and is positioned at a depth from the outer surface of the casting wheel.

[0008] In another aspect of this disclosure, the insert member includes a first tapered end and an opposing second tapered end to help position and hold the insert member within the mold cavity prior to the metal pouring of the casting wheel.

[0009] In another aspect of this disclosure, the insertion member includes a first lead screw extending outward from a first tapered end and a second lead screw extending outward from a second tapered end.

[0010] In another aspect of this disclosure, the first lead screw and the second lead screw are held in position in the final as-cast state of the casting wheel.

[0011] In another aspect of this disclosure, the insert member includes an internal hole filled with at least one filler material.

[0012] In another aspect of this disclosure, at least one filler material has a density different from that of the metal of the casting replaced by the insert member, and a higher melting point than the metal of the casting replaced by the insert member, in order to produce a locally lower apparent density within the casting.

[0013] In another aspect of this disclosure, the density of the insert is less than or equal to the density of the metal of the casting of the same volume that the insert replaces.

[0014] In another aspect of this disclosure, the casting includes a cylindrical hub fixed to a star-shaped section, and wherein the casting defines a cast wheel having a plurality of spokes defining an inner section, each of the plurality of spokes having one of a plurality of central portions.

[0015] According to several aspects, the casting comprises a cast wheel for automobiles, comprising multiple spokes, each spoke being substantially identical to the other spokes and equidistant from successive spokes to maintain a uniform weight distribution. Each spoke extends inward from a raised bead in a star-shaped section to a centrally located axle receiving portion. The central portion of each spoke is completely encased in the metal of the spokes. Inserts of glass material are positioned within the central portion, the melting point of which is higher than the melting point of the metal of the cast wheel to which the insert is displaced.

[0016] In another aspect of this disclosure, each insert member in the insert member includes an internal hole filled with at least one filler material.

[0017] In another aspect of this disclosure, the density of the filler material differs from that of the metal in the casting wheel to create a locally lower apparent density within the casting wheel.

[0018] In another aspect of this disclosure, the filler material includes one of polymers, agricultural waste, and by-products.

[0019] In another aspect of this disclosure, the insert member is permanently retained in position throughout the service life of the casting wheel, and the insert member is held in a specific position.

[0020] In another aspect of this disclosure, the insertion member includes at least one metal wire extending outward from an end of the insertion member to act as a retaining member for holding the insertion member in a specific position.

[0021] In another aspect of this disclosure, the insert member is sealed to ensure that the filling material within the cavity of the insert member does not contaminate the metal of the casting wheel. Prior to sealing, air present within the insert member is evacuated to a lower internal pressure to allow the filling material to vent due to the heat of casting.

[0022] According to several aspects, a method for producing a locally lower apparent density within a cast wheel includes: casting a cast wheel for an automobile, comprising a plurality of spokes, each of the plurality of spokes being substantially identical to the other spokes; extending each of the plurality of spokes inward from a raised bead in a star-shaped section to a centrally located axle receiving portion; completely enclosing the central portion of each of the spokes by means of metal from the spokes; and positioning an insert member in each portion of the central portion, the insert member defining a glass material having a melting point higher than the melting point of the cast wheel metal displaced by the insert member, and the insert member being permanently retained in position and held in a specific location for the service life of the cast wheel.

[0023] In another aspect of this disclosure, the method further includes at least one wire extending outward from the end of the insert member to act as a retaining member that holds the insert member in a specific position after casting the casting wheel.

[0024] In another aspect of this disclosure, the method further comprises: positioning a filler material within a cavity of an insert member; sealing the insert member to ensure that the filler material within the cavity does not contaminate the metal of the casting wheel; and evacuating air present within the insert member to a lower internal pressure before sealing the insert member, so as to allow the filler material to vent due to the heat of casting.

[0025] Further applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for illustrative purposes only and are not intended to limit the scope of this disclosure.

[0026] This article includes the following solutions.

[0027] Option 1. A casting system, including: Castings for automobiles, the castings having internal sections; Multiple central portions, each positioned within one of multiple regions of the internal segment, the internal segment being completely enclosed by the metal of the casting; and An insert member is positioned in each of the plurality of central portions, the insert member having a higher melting point than the melting point of the metal of the casting that the insert member displaces.

[0028] Option 2. The casting system according to Option 1, wherein the insert member defines a glass material and the casting defines a casting wheel.

[0029] Option 3. The casting system according to Option 2, wherein: The insertion member includes a length that maximizes the volume of the plurality of central portions; and The insertion member is spaced inward from the raised edge of the casting wheel by a certain distance and is positioned at a depth from the outer surface of the casting wheel.

[0030] Option 4. The casting system according to Option 2, wherein the insert member includes a first tapered end and an opposing second tapered end to help position and hold the insert member within the mold cavity before the metal is poured into the casting wheel.

[0031] Option 5. The casting system according to Option 4, wherein the insertion member comprises a first lead screw extending outward from the first tapered end and a second lead screw extending outward from the second tapered end.

[0032] Option 6. The casting system according to Option 5, wherein the first lead screw and the second lead screw are held in position in the final as-cast state of the casting wheel.

[0033] Option 7. The casting system according to Option 1, wherein the insert member includes an internal hole filled with at least one filler material.

[0034] Option 8. The casting system according to Option 7, wherein the density of the at least one filler material is different from the density of the metal of the casting replaced by the insert member, and the melting point of the at least one filler material is higher than the melting point of the metal of the casting replaced by the insert member, so as to produce a locally lower apparent density within the casting.

[0035] Option 9. The casting system according to Option 1, wherein the density of the insert member is less than or equal to the density of the metal of the casting of the same volume replaced by the insert member.

[0036] Option 10. The casting system according to Option 1, wherein the casting includes a cylindrical hub fixed to a star-shaped section, and wherein the casting defines a cast wheel having a plurality of spokes defining the inner section, each of the plurality of spokes having one of the plurality of central portions.

[0037] Option 11. Castings, including: A cast wheel for automobiles comprises a plurality of spokes, each of which is substantially the same as the other spokes and is equidistant from successive spokes to maintain a uniform weight distribution of the cast wheel. The multiple spokes extend inward from the raised bead of the star-shaped section to the centrally located axle receiving portion; The central portion of each of the plurality of spokes is completely encased in the metal of the plurality of spokes; and The glass insert is positioned in each of the central portions of the central portion, and the melting point of the insert is higher than the melting point of the metal of the casting wheel that the insert displaces.

[0038] Option 12. The casting according to Option 11, wherein the insert member includes an internal hole filled with at least one filler material.

[0039] Option 13. The casting according to Option 12, wherein the density of the filler material is different from the density of the metal of the casting wheel, so as to produce a locally lower apparent density within the casting wheel.

[0040] Option 14. The casting according to Option 12, wherein the filler material comprises one of a polymer material, agricultural waste, and scrap.

[0041] Option 15. The casting according to Option 11, wherein the insertion member is permanently retained in position during the service life of the casting wheel, and the insertion member is held in a specific position.

[0042] Option 16. The casting according to Option 15, wherein the insertion member includes at least one metal wire extending outward from an end of the insertion member to act as a retaining member holding the insertion member in the particular position.

[0043] Option 17. The casting according to Option 11, wherein: The insertion member is sealed to ensure that the filling material within the cavity of the insertion member does not contaminate the metal of the casting wheel; and Prior to sealing, the air present within the insert is evacuated to a lower internal pressure to allow the filler material to vent due to the heat of casting.

[0044] Option 18. A method for producing locally lower apparent density within a casting wheel, comprising: Casting a wheel for automobiles comprising multiple spokes, each of the multiple spokes being substantially identical to the other spokes in the multiple spokes; Each of the plurality of spokes extends inward from the raised bead in the star-shaped section to the centrally located axle receiving portion; The metal of the plurality of spokes completely encloses the central portion of each of the plurality of spokes; and The insert member is positioned in each of the central portions of the central portion, the insert member defining a glass material having a melting point higher than the melting point of the metal of the wheel to which the insert member is displaced, so that the insert member is permanently retained in position and held in a specific location for the service life of the wheel.

[0045] Option 19. The method according to Option 18 further includes at least one wire extending outward from the end of the insert member to act as a retaining member for holding the insert member in the particular position after the casting wheel has been cast.

[0046] Option 20. The method according to Option 18 further comprises: Position the filling material within the cavity of the insert member; Seal the insertion member to ensure that the filling material within the cavity does not contaminate the metal of the wheel; and Before sealing the insert, the air present in the insert is evacuated to a lower internal pressure to allow the filler material to vent due to the heat of casting. Attached Figure Description

[0047] The accompanying drawings described herein are for illustrative purposes only and are not intended to limit the scope of this disclosure in any way.

[0048] Figure 1 It is a frontal perspective view of a wheel casting according to an exemplary aspect, the casting having multiple glass devices embedded within it; Figure 2 Is Figure 1 The elevation view of the cross section obtained at section 2; Figure 3 This is a front elevation view of the glass device disclosed herein; Figure 4 yes Figure 3 A cross-sectional end perspective view of the glass device; Figure 5 This is a front perspective view of another glass device disclosed herein; Figure 6 Is Figure 5 Frontal elevation view of the cross section obtained at point 6 of the section; Figure 7 This is a front perspective view of another glass device disclosed herein; and Figure 8 Is Figure 7 The frontal elevation view of the cross section obtained at point 8 of the section. Detailed Implementation

[0049] The following description is merely exemplary and is not intended to limit this disclosure, its application, or its uses.

[0050] refer to Figure 1 The casting system 10, according to an exemplary aspect, provides a casting, which may be, for example, a cast wheel 12 for an automobile. The cast wheel 12 includes a plurality of spokes having defined internal sections, including a first spoke 14, a second spoke 16, a third spoke 18, a fourth spoke 20, a fifth spoke 22, and a sixth spoke 24 in a defined orientation. The number of spokes may be more or less than the depicted six spokes, as determined by the wheel designer, and may include a ten (10) spoke design as shown, also including spokes 24a, 24b, 24c, and 24d. Each of the spokes is substantially identical to the other spokes and is equidistant from successive spokes to maintain a uniform weight distribution, which provides rotational balance for the cast wheel 12. Each spoke extends inward from the raised bead 26 of the star-shaped section 28 to a centrally located axle receiving portion 30. The star-shaped section 28 is secured to a cylindrical hub 32.

[0051] It is known that during vehicle operation, the dynamic load on the wheel is high within the cylindrical hub 32 and lowest in the center portions 34 of the individual spokes, which define areas of internal sections completely enclosed by the metal of the casting. Eliminating the metal in the center portions 34 can be beneficial to minimize the overall weight and cost of the wheel, for example, by leaving voids in the cast spokes that define the center portions 34. The center portions 34 are completely enclosed by the metal of the spokes. Because wheel casting of metals such as aluminum or magnesium typically uses a sand casting process, sand is used to create voids. Therefore, a channel must be provided to remove the sand from the cast part after the casting process is complete to allow for voids to appear in the cast part. Enclosed areas within the spokes, such as the center portions 34, do not readily allow for the removal of sand from the center portions 34 after the casting operation.

[0052] Therefore, it is desirable to place a permanently retained fixed-volume element at the central portion 34 as a substitute for sand. (Reference) Figures 2 to 8 The melting point of the fixed-volume element, as shown and described in more detail, should be higher than that of the metal it replaces, and its density should be less than or equal to that of a wheel metal of the same volume, such as aluminum or magnesium.

[0053] refer to Figure 2 And refer again Figure 1To reduce the overall weight and cost of the casting wheel 12, a fixed-volume element defines an insert member 36, which is positioned within the respective central portions of the central portion 34. The melting point of the insert member 36 is higher than the melting point of the metal of the casting it displaces. The insert member 36 has a length 38 that maximizes the volume of the central portion 34. Each insert member in the insert member 36 is spaced inwardly from the raised edge 40 of the casting wheel 12 by a distance 42 and is positioned at a depth 44 below the outer surface 46 of the casting wheel 12. The insert member 36 is typically thicker than the wall thickness 48 of the cylindrical hub 32, therefore the insert member 36 is not placed within the wall of the cylindrical hub 32.

[0054] refer to Figure 3 According to several aspects, the insert member 36 has a body made of, for example, a glass material with a melting point higher than the metal being replaced, such as aluminum or magnesium. The glass material can be made from post-consumer mixed-color glass that is not currently being recycled or reused. The glass material can also be a ceramic material or produced from virgin materials. The shape of the insert member 36 can be described as having a glass cylindrical body portion 50, as shown in the image. Figure 3 The ampoule shown is as per reference. Figure 4 The tubular body portion shown, as referenced Figure 5 The capsule shown, and as referenced Figure 7 The ring-shaped object shown.

[0055] Continue to refer to Figure 3 To help position and hold the insert member 36 within the mold cavity before metal pouring, the insert member 36 may include a first tapered end 52 and an opposing second tapered end 54. Further holding capability can be provided by a first lead screw 56 extending outward from the first tapered end 52 and a second lead screw 58 extending outward from the second tapered end 54. The first tapered end 52, the second tapered end 54, the first lead screw 56, and the second lead screw 58 are retained in position in the final as-cast state of the casting wheel 12.

[0056] refer to Figure 4 And refer again Figures 1 to 3 The insert member 36 may also define a hollow glass sleeve 60 having a wall thickness 62 defining an internal orifice 64, which can maintain an internal pressure less than or greater than ambient pressure. The internal orifice 64 may also be filled with at least one filler material 66 having a density different from the cast metal and a higher melting point than the metal being replaced, to create a locally lower apparent density within the casting wheel 12. The internal orifice 64 of the insert member 36 is sealed within to prevent crushing of the insert member 36 during mold assembly and subsequent metal pouring. The filler material 66 may have a lower or higher density than the cast material. According to several aspects, the filler material 66 may be, but is not limited to, the following materials: • Polymer materials – such as abrasive forms of marine plastics, paint waste plastics, plastic scraps from PET or PA spinning, or recycled polyamide (PPA). • Agricultural waste – such as coconut husks, corn stalk fibers, animal hair, dried coffee grounds, walnut shell residue, cocoa shell residue, or rice husk waste. • Industrial waste materials - such as waste mold sand, ground metal oxides / slag / residue, or lint from automatic recycling machines.

[0057] refer to Figure 5 Insertion member 36 can also define vitreous capsule 68.

[0058] refer to Figure 6 And refer again Figure 5 The vitreous capsule 68 may include a first outer wall 70 and a second outer wall 72 facing each other. A first end wall 74 is opposite to the second end wall 76, and both end walls are oriented transversely to the outer walls. A closed cavity 78 is formed, similar to the reference [reference / ... Figure 4 The described internal hole 64 can be filled with at least one filler material 80, which has a different density than the cast metal and a higher melting point than the metal being replaced, to produce a locally lower apparent density within the casting wheel 12.

[0059] refer to Figure 7 The insert member 36 may also define the glass ring 82. The glass ring 82 includes a hollow central hole that does not contain any filling material.

[0060] refer to Figure 8 And refer again Figure 7 The glassy annulus 82 comprises a circular body 86 having a closed cavity 88. The closed cavity 88 may contain a filler material 90 with a density different from the casting material and a higher melting point than the metal being replaced, in order to create a locally lower apparent density within the casting wheel 12.

[0061] Materials that can be used in the systems and methods of this disclosure are presented in Table 1 below, which compares the properties of these materials with those of aluminum, a common material used in the manufacture of automobile wheels.

[0062] Table 1 The casting system 10 and method disclosed herein for producing locally lower apparent density within a casting wheel provide the use of a glass device positioned within an ampoule, capsule, annulus, or cylinder, the glass device having an inert, waste material filler having a melting point higher than the metal being replaced, to produce locally lower apparent density within the casting. The casting is designed such that an insert 36 is permanently retained in position throughout the life of the casting and holds the insert 36 in a specific location. The insert 36 may be hollow or filled with a material of a different density than the casting material (e.g., aluminum or magnesium). The insert 36 is designed such that the filler (if used) does not interact with the molten metal during the casting operation. The filler material may consist of materials typically considered to be waste from agricultural, industrial scraps, or post-consumer plastics or packaging. To reduce casting mass, the density of the filler is lower than the density of the metal being replaced, to produce locally lower apparent density in the finished casting. Localized reductions in density decrease excess casting mass and divert waste from landfills, thereby improving the sustainability of the casting process. Using denser waste can also be used to alter the resonant frequency of the casting, thus reducing structural noise.

[0063] The insert member 36 is sealed to ensure that the filler material, if present, does not contaminate the casting material. Air present within the insert member 36 can be evacuated to a lower internal pressure before sealing to allow the filler material to escape due to heat from the casting process. Alternatively, the air can be replaced with a gas that prevents the filler material from escaping due to heat from the casting process.

[0064] The casting is designed to hold the glass device in a specific position within the casting throughout its lifespan. This is accomplished, in several ways, using wires or rods, which are referenced below. Figure 3 The first rod 56 and the second rod 58 described are compatible alloys added to the tapered ends 52, 54 of the insert member 36, which subsequently engage with the forming cavity during a subsequent casting process to position the insert member 36. According to several aspects, a single wire can replace the first rod 56 and the second rod 58 and extend completely through the insert member 36. The tapered ends 52, 54 of the insert member 36 can also be designed such that the shape of the insert member 36 itself functions in the same manner as the first rod 56 and the second rod 58. The insert member 36 can be used with current core-setting techniques for semi-permanent molds or sand casting. The insert member 36 can also be used with low-pressure and high-pressure die casting techniques.

[0065] The systems and methods of this disclosure use one or more insert members 36 to alter the apparent density of the metal casting in local areas by replacing a portion of the cast metal corresponding to the volume of the insert member 36 with a different, cheaper, and lower-density material.

[0066] Reducing the mass of parts is desirable, as is ensuring the sustainability of the parts production process. The systems and methods disclosed herein help achieve sustainability goals by altering the density of low-stress regions of castings by replacing large quantities of material with one or more low-density materials that would otherwise be discarded, thereby reducing the mass of casting material required.

[0067] The systems and methods disclosed herein offer several advantages. These systems, comprising glass insert members 36, provide for reducing the amount of metal used in castings, resulting in both cost and mass savings, achieved by utilizing a lower apparent density. Another advantage is the utilization of waste stream materials to achieve a lower apparent density, which helps these components achieve sustainability and landfill reduction goals.

[0068] The description in this disclosure is merely exemplary in nature, and variations thereof without departing from the essential points of this disclosure are intended to fall within its scope. Such variations should not be considered as departing from the spirit and scope of this disclosure.

Claims

1. A casting system for automobiles, comprising: A casting for the automobile, the casting having internal sections and defining a casting wheel; Multiple central portions, each located in one of multiple regions of the internal segment, the internal segment being completely enclosed by the metal of the casting; as well as An insert member, positioned within each of the plurality of central portions and defining a body of glass material, wherein the melting point of the insert member is higher than the melting point of the metal of the casting to which the insert member displaces. The insertion member includes an internal cavity filled with at least one filling material, and The density of the at least one filler material is different from the density of the metal of the casting replaced by the insert member, and the melting point of the at least one filler material is higher than the melting point of the metal of the casting replaced by the insert member, so as to create a locally lower apparent density within the casting. The filling material includes agricultural waste.

2. The casting system according to claim 1, wherein: The insertion member includes a length that maximizes the volume of the plurality of central portions; and The insertion member is spaced inward from the raised edge of the casting wheel by a certain distance and is positioned at a depth from the outer surface of the casting wheel.

3. The casting system according to claim 1, wherein, The insert member includes a first tapered end and an opposite second tapered end to help position and hold the insert member within the mold cavity before the metal is poured into the casting wheel.

4. The casting system according to claim 3, wherein, The insertion member includes a first lead screw extending outward from the first tapered end and a second lead screw extending outward from the second tapered end.

5. The casting system according to claim 4, wherein, The first lead screw and the second lead screw are held in position in the final casting state of the casting wheel.

6. The casting system according to claim 1, wherein, The insertion member is defined as one of a glass hollow sleeve, a glass capsule, or a glass annulus.

7. The casting system according to claim 1, wherein, The density of the insert is less than or equal to the density of the metal of the casting of the same volume replaced by the insert.

8. The casting system according to claim 1, wherein, The casting includes a cylindrical hub fixed to a star-shaped section, and wherein the casting defines a cast wheel having a plurality of spokes defining the inner section, each of the plurality of spokes having one of the plurality of central portions.

9. A casting for automobiles, comprising: The cast wheel provided for the automobile comprises a plurality of spokes, each of the plurality of spokes being substantially the same as the other spokes of the plurality of spokes and being equidistant from successive spokes of the plurality of spokes to maintain a uniform weight distribution of the cast wheel; The multiple spokes extend inward from the raised bead of the star-shaped section to the centrally located axle receiving portion; The central portion of each of the plurality of spokes is completely encased in the metal of the plurality of spokes; as well as The glass insert is positioned in each of the central portions of the central portion, and the melting point of the insert is higher than the melting point of the metal of the casting wheel that the insert displaces. The insertion member includes an internal cavity filled with at least one filling material, and The density of the filler material differs from the density of the metal in the casting wheel, thereby creating a locally lower apparent density within the casting wheel. The filling material includes agricultural waste.

10. The casting according to claim 9, wherein, The insertion member is defined as one of a glass hollow sleeve, a glass capsule, or a glass annulus.

11. The casting according to claim 9, wherein, During the service life of the casting wheel, the insertion member is permanently retained in position and is held in a specific location.

12. The casting according to claim 11, wherein, The insertion member includes at least one metal wire extending outward from the end of the insertion member to act as a retaining member for holding the insertion member in the specific position.

13. The casting according to claim 9, wherein: The insertion member is sealed to ensure that the filling material within the cavity of the insertion member does not contaminate the metal of the casting wheel; as well as Prior to sealing, the air present within the insert is evacuated to a lower internal pressure to allow the filler material to vent due to the heat of casting.

14. A method for producing a locally lower apparent density within a casting wheel, comprising: Casting a wheel for automobiles comprising multiple spokes, each of the multiple spokes being substantially identical to the other spokes in the multiple spokes; Each of the plurality of spokes extends inward from the raised bead in the star-shaped section to the centrally located axle receiving portion; The metal of the plurality of spokes completely encloses the central portion of each of the plurality of spokes; as well as The insert member is positioned in each of the central portions of the central portion, the insert member defining a body of glass material having a melting point higher than that of the metal of the wheel to which the insert member is displaced, so that the insert member is permanently retained in position and held in a specific location for the service life of the wheel. The insertion member includes an internal cavity filled with at least one filling material. The density of the filler material differs from the density of the metal in the casting wheel, thereby creating a locally lower apparent density within the casting wheel. The filling material includes agricultural waste.

15. The method of claim 14, further comprising at least one wire extending outwardly from an end of the insert member to act as a retaining member holding the insert member in the particular position after the casting wheel has been cast.

16. The method of claim 14, further comprising: Position the filling material within the cavity of the insert member; Seal the insertion member to ensure that the filling material within the cavity does not contaminate the metal of the wheel; and Before sealing the insert, the air present in the insert is evacuated to a lower internal pressure to allow the filler material to vent due to the heat of casting.

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