WO2003013768A1

WO2003013768A1 - Method and apparatus for manufacturing multi-material powder metal components

Info

Publication number: WO2003013768A1
Application number: PCT/US2002/024497
Authority: WO
Inventors: Terry M. Cadle; Joel H. Mandel
Original assignee: Gkn Sinter Metals, Inc.
Priority date: 2001-08-03
Filing date: 2002-08-02
Publication date: 2003-02-20
Also published as: EP1412114A1; MXPA04001040A; CA2454652A1

Abstract

A method and apparatus for forming an object from first (105) and second powder metal (PM) (115) materials are disclosed. The method includes providing first and second surfaces to form a first cavity having a first opening, filling the first cavity with the first PM material (105) through the first opening, and compacting the first PM material (105) by way of a third surface that covers the first opening. The material additionally includes moving the second surface to create a second cavity bounded at least in part by the compacted first PM material (105), filling the second cavity with the second PM material (115) through a second opening, and compacting both the second PM material (115) and the compacted first PM material (105) by way of the third surface that covers both the first opening and the second opening.

Description

METHOD AND APPARATUS FOR MANUFACTURING MULTI-MATERIAL POWDER METAL COMPONENTS

CROSS-REFERENCE TO RELATED APPLICATION [0001] This application claims the benefit of U.S. provisional patent application number 60/309,893 entitled "Multi-Material Segmented Powder Metal Components" filed on August 3, 2001.

STATEMENT OF FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT [0002] Not applicable.

BACKGROUND OF THE INVENTION [0003] Referring to Fig. 1(a) (Prior Art), one of many electric motor designs incorporates an assembly 10 of plates/laminations 20 made of a soft magnetic material (usually mild steel) that alternate with other plates/laminations 30 made of a conducting material (usually copper) . The common arrangement of the plates 20,30 in the assembly 10 is in the form of a thick walled hollow cylinder. The plates 20,30 are held together by some means, for example by use of an adhesive. Assembly of the plates 20,30 is a complex, tedious and costly procedure. Additionally, in certain embodiments in which the thin plates 20,30 are made of stamped low carbon steel and stamped copper sheet, the iron stampings must be electrically insulated from the copper, which requires a special coating on the iron.

[0004] In the embodiments where the plates 20,30 are of uniform thickness such as shown in Fig. 1(b) (Prior Art), there are air gaps 40 between the adjacent plates that increase towards an outer diameter 50 of the assembly 10. These air gaps 40 can be filled with a polymer. Nevertheless, the air gaps 40 significantly detract from the magnetic flux carrying capacity of the assembly 10 since the polymer does not carry the magnetic flux. This effect can reduce the flux carrying potential of the assembly 10 by up to 40% compared to a no-gap design. [0005] In other embodiments of the assembly 10, the plates 20,30 are wedge-shaped segments 60 as shown in Fig. 1(c) (Prior Art) . In such embodiments, the air gaps are eliminated and so the magnetic flux carrying capacity is markedly improved. Unfortunately, the difficulties and costs of manufacturing the wedge-shaped segments 60 are high, particularly due to the special shape of the segments. Additionally, there are significant problems associated with the handling and orientation of the segments during storage and assembly.

[0006] The present inventors realized that conventional powder-metal technologies could potentially present a solution to the difficulties and costs associated with manufacturing electric motor stators employing such specially-shaped wedge-shaped segments. One experimental approach that was tried by the present inventors involved compacting copper powder into wedge-shaped segments, and then compacting polymer-coated iron powder into wedge- shaped segments, to produce individual mating segment shapes that could be assembled into the electric motor stator .

[0007] While this use of powder metals to form the wedge-shaped components 60 was originally thought to be a significant step forward in electric motor technology, insofar as it facilitated the manufacture of the specially-shaped segments 60, it did not overcome the major problem of handling and assembling the individual segments. In particular, this remained a problem because of the large number of wedge-shaped segments that are often used in electric motor stators, for example, 266 segments (e.g., 133 segments of copper and 133 segments of low carbon steel).

[0008] An alternate powder-metal technique that was pursued by the present inventors involved the use of a powder-filling device with wedge-shaped slit openings intended to be filled, alternately, with the copper and iron powders. By pouring the two powders simultaneously through these alternating slits into a suitable hollow cylinder-shaped forming die, and then compacting the powders contained in that die, it was hoped that the resulting electric motor stator would have the desired structure with the alternating copper and iron wedge- shaped segments 60. However, attempts to do this at even a very simple level proved to be impractical and resulted in an unacceptable cross-blending of the iron and copper powders in the different segment regions of the stator. [0009] The present inventors additionally attempted to manufacture an electric motor stator with the desired alternating wedge-shaped segments 60 using a powder-metal process in which separator punches were used to keep the copper and iron powders separate during a two-stage powder-filling and compaction sequence. Figs. 2 (A) -2 (G) show this process being applied in simplified form to manufacture a simple two-material component 125 having an outer annular section concentric about an inner cylindrical section (rather than to an electric motor stator with multiple wedge-shaped segments) . [0010] As shown in Figs. 2 (A) -2(G), this process (when employed to manufacture the simple component) employs a powder compaction tool 65 that includes a die 70, first and second lower punches 75 and 80, a separator punch 90, and a top punch 95. The punches 75, 80, 90 and 95 and the die 70 are moved by mechanical or hydraulic power when installed in a powder metal compacting press (not shown) . [0011] From a starting position at Fig. 2(A) at which the die 70 and punches 75,80 and 90 are all level with one another, the process commences at a first step shown in Fig. 2(B) by lowering the first punch 75 with respect to the die 70 and filling the resulting cavity with a first of the powder metals 105, e.g., copper. Next, at a second step shown in Fig. 2(C), the second punch 80 is also lowered with respect to the die 70 and the resulting cavity is filled with a second of the powder metals 115, e.g., iron .

[0012] Then, at a third step shown in Fig. 2(D), the separator punch 90 in between the two types of powder metals 100,105 is lowered with respect to the die 70 so that the two types of powder metals come into contact with one another. As shown, some settling occurs as the separator punch 90 is withdrawn. Next, at a fourth step shown in Fig. 2(E), the top punch 95 is lowered onto the powder metals 100,105 and applies pressure to compact the powder metals and form the solid two-material component 125. Finally, at a fifth step shown in Fig. 2(F) the die 70 is lowered relative to the punches 75,80 and 90 (or the punches are raised relative to the die) to expel the component 125 out of the die so that the component can be removed (as shown in Fig. 2(G)).

[0013] In the embodiment of Figs. 2 (A) -2(G), the die 70 forms the outer diameter of the final part. The two punches 75 and 80 move to form the cavities into which the first and second powder materials are filled, respectively, and assist in compressing these materials as shown in Fig. 2(E). The separator punch 90 keeps the two powder materials apart during the two powder-filling operations in Figs. 2(B) and 2(C) . Due to the compaction occurring in Fig. 2(E), an outer, annular section 135 formed by the first powder metal 105 is integrally joined to an inner, cylindrical section 145 formed by the second powder metal 115 along the interface between the sections .

[0014] Although the process of Figs. 2 (A) -2(G) was successfully applied to produce the simple component 125 having an outer annular section 135 concentric about an inner cylindrical section 145, the process could not be successfully implemented to manufacture a multi-segmented compact such as the electric motor stators. To begin, it was found that, despite the presence of the separator punch 90 during the powder-filling steps, significant cross-blending of the powders occurred as the separator punch 90 was lowered. In the case of electric motor stators, this cross-blending of the two powder materials will substantially detract from the performance of the electric motors employing the stators.

[0015] Further, as discussed above, the number of wedge- shaped segments 60 in electric motor stators often numbers in the hundreds. Consequently, to employ the process of Figs. 2 (A) -2 (G) in the manufacture of such stators, hundreds of lower punches such as the punches 75,80 and similarly large numbers of the separator punches such as the punch 90 are necessary. A compaction tool employing such a large number of punches is both excessively large and difficult and costly to produce. [0016] It would therefore be advantageous if a new process could be developed for manufacturing electric motor stators with wedge-shaped segments made from two different materials that was simpler and more cost- effective than the existing processes or experimental processes described above. It would be particularly advantageous if a new process was developed for manufacturing such electric motor stators through the use of powder metal technologies, in which the number of punches used to form the component was not excessive and in which the different powder metals did not overly mix with one another during the process.

SUMMARY OF THE INVENTION [0017] In the present invention, a powder metal material is compacted with a light compaction pressure to have sufficient compacted strength to stand alone within the compaction tooling when the punches used to hold the material together are removed. Further, the material when so compacted is capable of receiving, within cavities in the material, a second material without significant disintegration of the compacted material upon receiving the second material (or mixing of the two materials) .

[0018] In accordance with the present invention, a multi-material segmented component is formed from two metal powders, for example, copper and polymer-coated iron for the alternating segments of an electric motor stator, respectively (or an electric motor rotor) . In practicing the invention, a component to be formed from two (or more) different powder metal materials is made by first precompacting one of the materials into a shape that defines a cavity into which one of the other powder metals is filled. The first powder material is precompacted to a low density, which is less than its final density, but enough compaction pressure is applied to give it sufficient structural integrity to hold its shape when cavity forming punches are withdrawn and the other powder is filled into the resulting cavity or cavities. Precompaction is followed by the withdrawal of one or more punches to form one or more cavities within the precompacted material, which in turn is followed by filling of the cavities with one or more other powder materials. Following that, all of the materials are simultaneously compacted to the final density of the compact .

[0019] In a preferred form, the present invention is applied to form an electric motor stator (or rotor) in which a cavity-forming punch is in the shape of one of the two sets of wedge-shaped segments. Upon precompression of one of the powders which is filled into the regions formed between the segments of the cavity forming punch, the cavity-forming punch is withdrawn, which results in cavities that are ready to be filled with the other powder. Following that, both powders are simultaneously compressed to their final compaction densities and the finished compact is ejected from the die. The invention provides a technique for making powder metal products of two or more different powder metal materials in which separator punches are not needed and/or in which the individual segments can be relatively small or thin.

[0020] In particular, the present invention relates to a method of forming an object from first and second powder metal materials. The method includes providing first and second surfaces to form a first cavity having a first opening, and filling the first cavity with the first powder metal material through the first opening. The method further includes compacting the first powder metal material sufficiently so as to maintain the shape of the first cavity by way of a third surface that covers the first opening, and moving the second surface to create a second cavity bounded at least in part by the compacted first powder metal material. The method additionally includes filling the second cavity with the second powder metal material through a second opening, and compacting both the second powder metal material and the compacted first powder metal material by way of a third surface that covers both the first opening and the second opening.

[0021] The present invention additionally relates to an apparatus for forming a component from first and second powder materials. The apparatus includes a die forming a first surface that defines at least in part a first cavity, and a first punch capable of being moved with respect to the die, where the first punch forms a second surface that defines at least in part the first cavity when the first punch is in a first position with respect to the die. The apparatus additionally includes a second punch forming a third surface, where the second punch is lowered to compact a first material placed within the first cavity when the first punch defines the first cavity. After the first material has been compacted by the second punch, the first punch is moved to a second position with respect to the die so that a second cavity is formed at least in part by an exposed surface of the first material that formerly interfaced the first punch. After the second cavity is formed, the second punch is able to be lowered to compact both the first material and a second material placed within the second cavity. [0022] The present invention further relates to an apparatus for forming a component from first and second powder metal materials. The apparatus includes a die for providing an outer surface that in part defines a first cavity, and a first punch for providing a retractable inner surface that in part defines the first cavity, where a second cavity is formed when the inner surface is retracted. The apparatus also includes a second punch moveable relative to the first and second cavities and to apply pressure successively to first and second powder metal materials within the first and second cavities, respectively. [0023] These and other objects and advantages of the invention will be apparent to those skilled in the art from the detailed description and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS [0024] Fig. 1(A) is a perspective view of a Prior Art stator for an electric motor;

[0025] Fig. 1(B) is a detail view of uniform thickness plates that are used in certain Prior Art embodiments of electric motor stators such as that shown in Fig 1 (a) ; [0026] Fig. 1(C) is a detail view of plates that are wedge-shaped segments that are used in other Prior Art embodiments of electric motor stators;

[0027] Figs. 2 (A) -2(G) are schematics showing a sequence of steps of an experimental technique for performing multi-material compaction using a separator punch; [0028] Figs. 3 (A) -3(G) are schematics showing a sequence of steps of a multi-material compaction technique in accordance with an embodiment of the present invention; [0029] Fig. 4 is a perspective, exploded view of several components of a tool used to perform the technique of Figs. 3 (A) -3(G) to produce an electric motor stator, including segments of a cavity-forming punch disassembled from a portion of a die, in accordance with an embodiment of the present invention; and

[0030] Fig. 5 is a sectional view of the tool of Fig. 4 with a cavity-forming punch retracted.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [0031] Referring to Figs. 3 (A) -3 (G) , a new process for manufacturing components from multiple powder-metal materials is shown. The new process is applicable, as discussed with reference to Figs. 4 and 5, to the manufacture of complicated components such as electric motor stators. However, the process is first shown in Figs. 3 (A) -3(G) being performed in simplified form to manufacture a simple two-material component 225 similar to the component 125 discussed with reference to Figs. 2 (A) -2(G), in order to highlight the differences between the present inventive process and the process of Figs. 2 (A)-2 (G) .

[0032] As shown in Figs. 3 (A) -3(G), the new process (when employed to manufacture the simple component 225) employs a power compaction tool 165 that includes a die 170, first and second lower punches 175 and 180, and a top punch 195. The die 170 and the punches 175, 180 and 195 are moved by mechanical or hydraulic power when installed in a powder metal compacting press (not shown) . [0033] From a starting position shown in Fig. 3(A) at which the die 170 and the punches 175, 180 are all level with one another, the process commences at a first step shown in Fig. 3(B) by lowering the first punch 175 with respect to the die 170 and filling the resulting cavity with a first of the powder metals 205, e.g., copper. Next, at a second step shown in Fig. 3(C), the top punch 195 is lowered and lightly compacts the powder metal 205. The die 170 is also lowered to stay level with the second punch 180, which moves downward under the pressure of the top punch 195. However, the first punch 175 remains constant in its position as the top punch 195 moves downward so that the powder metal 205 is compacted. From other reference points, the first punch 175 moves upward toward the top punch 195, or the two punches 175, 195 move toward one another.

[0034] Next, at a third step shown in Fig. 3(D), the top punch 195 is raised and the second punch 180 is lowered to expose a cavity 190 formed within the compacted powered material 205. At a fourth step shown in Fig. 3(E), a second of the powder materials 215 is filled into the cavity 190. Then, at a fifth step shown in Fig. 3(F), the top punch 195 is lowered under power, while the die 170 and first and second punches 175, 180 are held stationary so that both the first and second powder materials 205, 215 are compacted (from a different vantage point, the first and second punches 175, 180 are raised relative to the top punch 195, or all of the punches are moved together) . Finally at a sixth step shown in Fig. 3(G), the top punch 195 is raised, and the die 170 is lowered relative to the first and second punches 175, 180 (or the punches are raised relative to the die) , causing the finished component 225 to be ejected from the die so that it can be slid off of the tool 165 and so that the process can begin again. [0035] The new process of Figs. 3 (A) -3(G) has at least two advantages in comparison with the process of Figs. 2 (A) -2(G). First the new process successfully creates the component 225 out of the two powder materials 205, 215 without significant mixing of the two materials. That is, the precompaction of the first material 205 prevents significant mixing of the first and second materials 205,215 when the second material is added in Fig. 3(E). Thus, the process of Figs. 3 (A) -3 (G) is much more suitable for crafting components such as electric motor stators in which it is important for the different sections of the components made from different materials to be separate from one another. Second, the process of Figs. 3 (A) -3 (G) does not require separator punches such as the punch 90 of Figs. 2 (A) -2(G). Thus, the tool 165 is simpler, smaller and more cost-effective than the tool 65.

[0036] Turning to Figs. 4 and 5, tool components are shown (in simplified form) that can be used to apply the new process of Figs. 3 (A) -3(G) to form an electric motor stator having the alternating wedge-shaped segments 60 of copper and iron. The tool components will include an inner punch 301 (see Fig. 5) similar to the punches 80 and 180 of Figs. 2 and 3, respectively, which defines the inner diameter of the stator. Additionally, the tool components will include a die 270 that both has a wall 275 to define the outer diameter of the stator (a portion of which is shown in phantom in Fig. 5) , and also includes a slotted bottom 280. Further, the tool components will also include a punch 290 that is similar to the punch 175 of Figs. 3 (A) -3(G), but which has projections 295 that are in the shape of one of the two sets of wedge-shaped segments 60, for example, the copper segments. Three such punch projections 295 of this punch 290, referred to herein as the cavity-forming punch, are shown in Fig. 4, and six such projections are shown in Fig. 5, it being understood that these spaced segments would continue for 360 degrees in an actual tool for forming stators. By using a single punch 290 that includes all of the punch projections 295, there are no longer problems associated with the use of many punches in forming the many wedge-shaped components 60 of an electric motor stator. However, in alternate embodiments, the punch projections 295 can be separate from one another (as individual punches) rather than be part of the single punch 290, or several of the projections 295 can be mounted on one punch, with others of the projections being mounted on other punches. [0037] Specifically, the cavity-forming punch 290 is employed in conjunction with the die 270 to form the stator with the wedge-shaped segments 60 as follows. As shown in Figs. 4-5, the cavity-forming punch projections 295 are wedge-shaped to match the shape of the wedge- shaped segments 60. In operation, the projections 295 are disposed about an axis 300 (see Fig. 4) of the die 270 and around the inner punch 301 (Fig. 5) so as to define the entire array of spaced wedge-shaped segments 60. The punch segments 295 are first inserted through close fitting slots 310 in the bottom 280 of the die 270. The slots 310 would be in the same spaced array as the punch projections 295, centered on the axis 300. One of the powder materials (e.g., coated iron) is then poured into cavities formed between the projections 295 of the cavity-forming punch 290, and also defined by the wall 275 of the die 270 and the inner punch 301, while the projections 295 extend into the die. The powder within these radial cavities is then lightly compacted to just enough pressure to enable the powder material to be free standing. This compaction is performed by a top punch 303 (see Fig. 5) similar to the top punches 95,195 of Figs. 2 and 3. As the top punch 303 compresses the material in between the projections 295, the projections may move downward somewhat.

[0038] Once the first powder material has been compacted, the projections 295 can be withdrawn from the die 270 through the slots 310 in the bottom 280 of the die 270. Upon withdrawal of the projections 295 so that upper ends 315 of the projections are flush with the upper surface of the bottom 280 of the die 270 (as shown in Fig. 5), the remaining second powder material (e.g., copper powder) can be poured into the resulting cavities in between the precompacted wedge-shaped segments formed by the first powder material. Then the top punch 303 is again lowered to simultaneously compress both powder materials to their final compaction density, with the bottom 280 of the die 270 and the upper ends 315 of the projections 295 supporting the bottom of the compact. Finally, upon finishing the compaction process, the finished stator can be ejected out of the tooling components (e.g., by lifting the stator by again raising the projections 295 through the slots 310 or by lowering the die 270) . [0039] The types of powder materials used in the process of Figs. 4-5 can affect its efficiency. In a preferred embodiment, the iron powder in particular is a special formulation that is known in the powder metal industry as "coated iron powder." In the case of fabricating electric motor stators, the polymer coating on every iron particle provides the essential magnetic insulation between the iron and the copper segments when they are assembled. This coating also insulates each iron particle from its neighbors, restricting stray electrical currents known as "eddy currents" that can cause power loss and over-heating. By adjusting the loose-filling (apparent) density of one of the powders by means of adding an organic wax powder, a compatible combination was arrived at. It is generally preferable to preco press the wedge-shaped segments 60 that are of the greater thickness (if all of the segments are not of identical thickness) , in this case, the coated iron segments .

[0040] Also, while the ejection of the compacted stator or other component at the end of the process (e.g., as shown in Fig. 3(G)) presented a problem due to friction, the use of a dry powder die-wall spray lubricant as taught in U.S. Patent No. 6,190,605, which is hereby incorporated by reference, solves this problem. The present invention in this manner provides a process capable of being utilized to manufacture the multi- segmented magnetic stator component in a single shot compaction cycle.

[0041] While the foregoing illustrates and describes the preferred embodiments of this invention, it is to be understood that the invention is not limited to the precise construction herein disclosed. The invention can be embodied in other forms without departing from the spirit or essential attributes of the invention. For example, more than two different materials could be used to form the segments of the compact. Practice of the invention with respect to two materials can be termed duplex powder metallurgy, while practice of the invention with respect to multiple (more than two) materials can be termed multi-material powder metallurgy. Also, the inventive process can be employed not only with respect to electric motor stators as shown, but other motor components such as rotors, as well as a variety of other components made from two or more different materials. Accordingly, reference should be made to the following claims, rather than to the foregoing specification, as indicating the scope of the invention.

Claims

CLAIMS We claim:

1. A method of forming an object from first and second powder metal materials, the method comprising: providing first and second surfaces to form a first cavity having a first opening; filling the first cavity with the first powder metal material through the first opening; compacting the first powder metal material sufficiently so as to maintain the shape of the first cavity by way of a third surface that covers the first opening; moving the second surface to create a second cavity bounded at least in part by the compacted first powder metal material; filling the second cavity with the second powder metal material through a second opening; compacting both the second powder metal material and the compacted first powder metal material by way of a third surface that covers both the first opening and the second opening.

2. The method of claim 1, further comprising: moving the third surface to expose the first and second openings, which together form an overall opening; and ejecting a compacted component formed from the compacted first and second powder metal materials out of the overall opening.

3. The method of claim 1, further comprising: providing a fourth surface, wherein the first cavity is formed by the first surface, second surface and fourth surface; wherein, during the compacting of the first powder metal material, the first, second and third surfaces move with respect to the fourth surface, causing the first cavity to be reduced in size to form a reduced first cavity, and thus causing the first powder metal material to be compacted.

4. The method of claim 3 wherein, during the compacting of both the second powder metal material and the compacted first powder metal material, the third surface moves with respect to the first, second and fourth surfaces, causing an overall cavity comprising the reduced first cavity and the second cavity to be reduced in size.

5. The method of claim 1, wherein the first surface is a die that includes an outer cylindrical wall and a plurality of bottom radial spoke surfaces extending from the outer cylindrical wall inward.

6. The method of claim 5, wherein the second surface is a punch that includes a plurality of radial spoke wall portions that, along bottom edges, interface radial edges of the bottom radial spoke surfaces and extend upwards along the outer cylindrical wall.

7. The method of claim 6, wherein the first cavity includes a plurality of radial segments respectively positioned in between the respective radial spoke wall portions, the bottom radial spoke surfaces, the outer cylindrical wall, and an additional inner cylindrical wall .

8. The method of claim 6, wherein the moving of the second surface includes withdrawing the plurality of radial spoke wall portions downward through radial slots formed between the radial edges of the bottom radial spoke surfaces, until radial top surfaces of the radial spoke wall portions are parallel with the bottom radial spoke surfaces.

9. The method of claim 8, wherein the first powder metal material is coated iron, and the second powder metal material is copper.

10. The method of claim 9, wherein the compacted first and second powder metal materials form a stator with alternating copper and iron wedges.

11. An apparatus for forming a component from first and second powder materials, the apparatus comprising: a die forming a first surface that defines at least in part a first cavity; a first punch capable of being moved with respect to the die, wherein the first punch forms a second surface that defines at least in part the first cavity when the first punch is in a first position with respect to the die; and a second punch forming a third surface; wherein the second punch is lowered to compact a first material placed within the first cavity when the first punch defines the first cavity; wherein, after the first material has been compacted by the second punch, the first punch is moved to a second position with respect to the die so that a second cavity is formed at least in part by an exposed surface of the first material that formerly interfaced the first punch; and wherein, after the second cavity is formed, the second punch is able to be lowered to compact both the first material and a second material placed within the second cavity.

12. The apparatus of claim 11, wherein the die includes an outer cylindrical wall and a plurality of bottom radial spoke surfaces extending from the outer cylindrical wall inward.

13. The apparatus of claim 12, wherein the first punch includes a plurality of radial spoke wall portions that, along bottom edges, interface radial edges of the bottom radial spoke surfaces and extend upwards along the outer cylindrical wall.

14. The apparatus of claim 13, wherein the first cavity includes a plurality of radial segments respectively positioned in between the respective radial spoke wall portions, the bottom radial spoke surfaces, the outer cylindrical wall, and an additional inner cylindrical wall.

15. The apparatus of claim 14, wherein the moving of the second surface includes withdrawing the plurality of radial spoke wall portions downward through radial slots formed between the radial edges of the bottom radial spoke surfaces, until radial top surfaces of the radial spoke wall portions are parallel with the bottom radial spoke surfaces .

16. The apparatus of claim 15, wherein the first powder material is coated iron, and the second powder material is copper.

17. The apparatus of claim 16, wherein the compacted first and second powder materials form a stator with alternating copper and iron wedges.

18. The apparatus of claim 11, further comprising a third punch capable of being moved in relation to both the die and the first punch, wherein the first cavity is defined in part by the third punch when the third punch is lowered in relation to the die and the first punch.

19. The apparatus of claim 11, wherein the component is ejected from the apparatus by lifting the second punch, raising the first punch in relation to the die, and causing the component to slide off of the apparatus .

20. An apparatus for forming a component from first and second powder metal materials, the apparatus comprising: a die for providing an outer surface that in part defines a first cavity; a first punch for providing a retractable inner surface that in part defines the first cavity, wherein when the inner surface is retracted, a second cavity is formed; and a second punch moveable relative to the first and second cavities and to apply pressure successively to first and second powder metal materials within the first and second cavities, respectively.

21. The apparatus of claim 20, further comprising means for defining a hollow interior of the component.