Metal injection molding multiple dissimilar materials to form composite electric machine rotor and rotor sense parts

Abstract

A method for forming composite motor parts of two or more dissimilar materials by injection molding. Two or more different powder materials are injected under heat and pressure into cavities of a cylindrical-shaped mold and allowed to solidify to form a composite green compact. The final part may be used in machines of the type including permanent magnet, synchronous reluctance, switch reluctance and induction machines.

What is claimed is:  
     
         1 . A method for injection molding composite rotor components, the method comprising: 
 injecting a ferromagnetic powder material from a first injection unit under heat and pressure into a first mold cavity, and allowing the ferromagnetic material to solidify;    injecting a non-ferromagnetic powder material from a second injection unit under heat and pressure into a second mold cavity adjacent the ferromagnetic material, and allowing the non-ferromagnetic material to solidify to thereby produce a composite injection molded rotor component.    
     
     
         2 . The method of  claim 1 , wherein the ferromagnetic powder material is soft ferromagnetic powder metal or hard ferromagnetic powder metal.  
     
     
         3 . The method of  claim 1 , wherein the ferromagnetic powder material is a soft ferromagnetic powder metal selected from the group consisting of Ni, Fe, Co and alloys thereof.  
     
     
         4 . The method of  claim 1 , wherein the ferromagnetic powder material is a soft ferromagnetic high purity iron powder with a minor addition of phosphorus.  
     
     
         5 . The method of  claim 1 , wherein the non-ferromagnetic powder material is an austenitic stainless steel.  
     
     
         6 . The method of  claim 1 , wherein the non-ferromagnetic powder material is an AISI 8000 series steel.  
     
     
         7 . The method of  claim 1 , wherein the ferromagnetic and non-ferromagnetic powder materials are each combined with a binder prior to injecting.  
     
     
         8 . The method of  claim 7 , further comprising the steps of: 
 ejecting the composite component from the mold;    subjecting the composite component to debinding to provide a composite part which is essentially free of binder; and    sintering the composite part.    
     
     
         9 . The method of  claim 1 , wherein the first and second injection units are part of a single injection molding machine, with each unit positioned to inject the respective powder material into the respective first and second mold cavity of a single mold.  
     
     
         10 . The method of  claim 1 , wherein the first and second injection units are part of separate injection molding machines, and a single mold having the first and second mold cavities is transferred sequentially to each machine for injecting the respective powder material into the respective first and second mold cavity.  
     
     
         11 . The method of  claim 1 , wherein the first mold cavity is in a first mold and the second mold cavity is in a second mold, and wherein the ferromagnetic powder material is injected into and solidified in the first mold cavity, then removed and inserted into the second mold, and the non-ferromagnetic powder material is injected into and solidified in the second mold cavity.  
     
     
         12 . The method of  claim 1 , further comprising injecting one or more additional powder materials into one or more additional mold cavities, each additional powder material having a different composition than the ferromagnetic and non-ferromagnetic powder materials, to form a composite injection molded component of at least three or more different materials.  
     
     
         13 . The method of  claim 12 , wherein the ferromagnetic powder material is a soft ferromagnetic metal and one additional powder material is a hard ferromagnetic powder metal thereby forming a permanent magnet rotor component.  
     
     
         14 . The method of  claim 12 , wherein the ferromagnetic powder material is a hard ferromagnetic metal and one additional powder material is a plastic filler material thereby forming a rotor sense ring component.  
     
     
         15 . The method of  claim 1 , wherein the non-ferromagnetic powder material is injected concurrently with the ferromagnetic powder material.  
     
     
         16 . The method of  claim 1 , wherein the non-ferromagnetic powder material is injected after the ferromagnetic powder material is allowed to solidify.  
     
     
         17 . The method of  claim 1  further comprising mounting the composite component on a shaft to form a powder metal rotor assembly.  
     
     
         18 . A method for injection molding composite rotor components, comprising the steps of: 
 preparing at least two different feedstocks, each feedstock comprising a mixture of a powder material and a binder, the powder materials being selected from the group consisting of hard ferromagnetic, soft ferromagnetic and non-ferromagnetic;    feeding each feedstock to a respective injection unit;    melting the feedstocks; and    molding the feedstocks into a composite compact of desired shape comprising at least two different materials by injecting melted feedstock from each injection unit under heat and pressure into a respective portion of a mold, and allowing the feedstocks to solidify.    
     
     
         19 . The method of  claim 18 , further comprising the steps of: 
 ejecting the compact from the mold;    subjecting the compact to debinding to provide a part which is essentially free of binder; and    sintering the part.    
     
     
         20 . The method of  claim 18 , wherein each feedstock is injected into the respective portion of a single mold to form the composite compact.  
     
     
         21 . The method of  claim 20 , wherein the injection units form a single injection molding machine, with each unit positioned to inject feedstock into the respective portion of the single mold.  
     
     
         22 . The method of  claim 21 , wherein all feedstocks are injected concurrently.  
     
     
         23 . The method of  claim 21 , wherein the feedstocks are injected sequentially.  
     
     
         24 . The method of  claim 20 , wherein each injection unit is part of a separate injection molding machine, and the single mold is transferred sequentially to each machine for injecting the respective feedstock into the respective portion of the single mold.  
     
     
         25 . The method of  claim 18 , comprising repeating the steps of injecting one melted feedstock into the respective portion of the mold and allowing the feedstock to solidify, followed by transferring the solidified feedstock to another mold, until each feedstock has been injected, to thereby form the composite compact.  
     
     
         26 . The method of  claim 18 , wherein the soft ferromagnetic powder metal is Ni, Fe, Co or an alloy thereof.  
     
     
         27 . The method of  claim 18 , wherein the soft ferromagnetic powder metal is high purity iron powder with a minor addition of phosphorus.  
     
     
         28 . The method of  claim 18 , wherein the non-ferromagnetic powder metal is an austenitic stainless steel.  
     
     
         29 . The method of  claim 18 , wherein the non-ferromagnetic powder metal is an AISI 8000 series steel.  
     
     
         30 . The method of  claim 18 , further comprising mounting the composite component on a shaft to form a powder metal rotor assembly.  
     
     
         31 . The method of  claim 18 , wherein a first feedstock is a soft ferromagnetic powder metal injected into an inner annular region of a cylinder-shaped mold, and a second feedstock is a non-ferromagnetic powder metal injected into discrete regions within an outer annular region of the mold so as to leave spaces between each discrete region, and a third feedstock is a hard ferromagnetic powder metal injected into the spaces between the discrete regions of the outer annular region of the mold, whereby upon solidifying a composite powder metal component for a surface permanent magnet machine is formed having an inner annular magnetically conducting segment and an outer annular segment of a plurality of alternating polarity permanent magnets separated by magnetically non-conducting segments.  
     
     
         32 . The method of  claim 18 , wherein a first feedstock is a soft ferromagnetic powder metal injected into an inner annular region of a cylinder-shaped mold, and a second feedstock is a hard ferromagnetic powder metal injected into an outer annular region of the mold, whereby upon solidifying a composite powder metal component for a surface permanent magnet machine is formed having an inner annular magnetically conducting segment and an outer annular permanent magnet ring.  
     
     
         33 . The method of  claim 18 , wherein a first feedstock is a soft ferromagnetic powder metal injected into an inner annular region of a cylinder-shaped mold, and a second feedstock is a non-ferromagnetic powder metal injected into discrete regions within an outer annular region of the mold so as to leave spaces between each discrete region, whereby upon solidifying a composite powder metal component for a surface permanent magnet machine is formed having an inner annular magnetically conducting segment and an outer annular segment of a plurality of spaces separated by magnetically non-conducting segments, the method further comprising affixing pre-fabricated magnets in the spaces in an arrangement of alternating polarity.  
     
     
         34 . The method of  claim 18 , wherein a first feedstock is a non-ferromagnetic powder metal injected into discrete regions within an annular region of the mold so as to leave spaces between each discrete region, and a second feedstock is a hard ferromagnetic powder metal injected into the spaces between the discrete regions of the annular region of the mold, whereby upon solidifying a composite powder metal component for a surface permanent magnet machine is formed having an annular segment of a plurality of alternating polarity permanent magnets separated by magnetically non-conducting segments.  
     
     
         35 . The method of  claim 18 , wherein a first feedstock is a soft ferromagnetic powder metal injected into an inner annular region of a cylinder-shaped mold, a second feedstock is a non-ferromagnetic powder metal injected into discrete first regions within an outer annular region of the mold so as to leave spaces between each discrete first region, and wherein the first feedstock is further injected into two discrete second regions between the first regions so as to leave a radially inner circumferentially extending space and a radially extending space between the two discrete regions, and wherein the second feedstock is further injected into the radially extending spaces, and a third feedstock is a hard ferromagnetic powder metal injected into the radially inner circumferentially extending spaces between the discrete first regions of the mold, whereby a composite powder metal component for a circumferential type interior permanent magnet machine is formed having an inner annular magnetically conducting segment and an outer permanent magnet segment of a plurality of alternating polarity permanent magnets separated by magnetically non-conducting barrier segments and radially embedded by magnetically conducting segments with intermediate magnetically non-conducting bridge segments.  
     
     
         36 . The method of  claim 18 , wherein a first feedstock is a soft ferromagnetic powder metal injected into an inner annular region of a cylinder-shaped mold, a second feedstock is a non-ferromagnetic powder metal injected into discrete first regions within an outer annular region of the mold so as to leave spaces between each discrete first region, and wherein the first feedstock is further injected into two discrete second regions between the first regions so as to leave a radially inner circumferentially extending space and a radially extending space between the two discrete regions, and wherein the second feedstock is further injected into the radially extending spaces, whereby a composite powder metal component for a circumferential type interior permanent magnet machine is formed having an inner annular magnetically conducting segment and an outer permanent magnet segment of a plurality of circumferentially extending spaces separated by magnetically non-conducting barrier segments and radially embedded by magnetically conducting segments with intermediate magnetically non-conducting bridge segments, the method further comprising affixing pre-fabricated magnets in the circumferentially extending spaces in an arrangement of alternating polarity.  
     
     
         37 . The method of  claim 18 , wherein a first feedstock is a non-ferromagnetic powder metal injected into discrete first regions within an annular region of the mold so as to leave spaces between each discrete first region, and wherein a second feedstock is a soft ferromagnetic powder metal injected into two discrete second regions between the first regions so as to leave a radially inner circumferentially extending space and a radially extending space between the two discrete regions, and wherein the first feedstock is further injected into the radially extending spaces, and a third feedstock is a hard ferromagnetic powder metal injected into the radially inner circumferentially extending spaces between the discrete first regions of the mold, whereby a composite powder metal component for a circumferential type interior permanent magnet machine is formed having an outer permanent magnet segment of a plurality of alternating polarity permanent magnets separated by magnetically non-conducting barrier segments and radially embedded by magnetically conducting segments with intermediate magnetically non-conducting bridge segments.  
     
     
         38 . The method of  claim 18 , wherein a first feedstock is a non-ferromagnetic powder metal injected into an inner annular region of a cylinder-shaped mold, a second feedstock is a soft ferromagnetic powder metal injected into discrete first regions within an outer annular region of the mold so as to leave spaces between each discrete first region, and wherein the first feedstock is further injected into discrete radially outer second regions between the first regions so as to leave a radially inner radially extending space between each of the adjacent first regions, and a third feedstock is a hard ferromagnetic powder metal injected into the radially extending spaces between the discrete first regions of the mold, whereby a composite powder metal component for a spoke type interior permanent magnet machine is formed having an inner annular magnetically non-conducting segment and an outer annular segment of a plurality of alternating polarity permanent magnets separated by magnetically conducting segments and embedded by magnetically non-conducting segments.  
     
     
         39 . The method of  claim 18 , wherein a first feedstock is a non-ferromagnetic powder metal injected into an inner annular region of a cylinder-shaped mold, a second feedstock is a soft ferromagnetic powder metal injected into discrete first regions within an outer annular region of the mold so as to leave spaces between each discrete first region, and wherein the first feedstock is further injected into discrete radially outer second regions between the first regions so as to leave a radially inner radially extending space between each of the adjacent first regions, whereby a composite powder metal component for a spoke type interior permanent magnet machine is formed having an inner annular magnetically non-conducting segment and an outer annular segment of a plurality of radially extending spaces separated by magnetically conducting segments and embedded by magnetically non-conducting segments, the method further comprising affixing pre-fabricated magnets in the radially extending spaces in an arrangement of alternating polarity.  
     
     
         40 . The method of  claim 18 , wherein a first feedstock is a soft ferromagnetic powder metal injected into discrete first regions within an annular region of the mold so as to leave spaces between each discrete first region, and wherein a second feedstock is a non-ferromagnetic powder metal injected into discrete radially outer second regions between the first regions so as to leave a radially inner radially extending space between each of the adjacent first regions, and a third feedstock is a hard ferromagnetic powder metal injected into the radially extending spaces between the discrete first regions of the mold, whereby a composite powder metal component for a spoke type interior permanent magnet machine is formed having an annular segment of a plurality of alternating polarity permanent magnets separated by magnetically conducting segments and embedded by magnetically non-conducting segments.  
     
     
         41 . The method of  claim 18 , wherein a first feedstock is a soft ferromagnetic powder metal injected into a first region of a cylinder-shaped mold to form a pattern of a plurality of equally spaced axially extending slots adjacent an exterior circumferential surface of the mold, and a second feedstock is a non-ferromagnetic powder metal injected into a plurality of discrete second regions of the mold in a radially outer portion of each slot adjacent the exterior circumferential surface of the mold, whereby a composite powder metal component for an induction machine is formed having a magnetically conducting segment and a plurality of magnetically non-conducting segments enclosing slot openings.  
     
     
         42 . The method of  claim 18 , wherein a first feedstock is a soft ferromagnetic powder metal injected into one or more discrete first regions in a cylinder-shaped mold, and a second feedstock is a non-ferromagnetic powder metal injected into one or more discrete second regions in the mold, the discrete second regions in alternating relation with the first discrete regions, whereby a composite powder metal component for a synchronous reluctance machine is formed having one or more magnetically conducting segments alternating with one or more magnetically non-conducting segments.  
     
     
         43 . The method of  claim 18 , wherein a first feedstock is a soft ferromagnetic powder metal injected into a first region in a cylinder-shaped mold, the first region having a yoke and teeth configuration, and a second feedstock is a non-ferromagnetic powder metal injected into discrete second regions in the mold, the discrete second regions positioned between the teeth of the first region, whereby a composite powder metal component for a switched reluctance machine is formed having a magnetically conducting segment and a plurality of magnetically non-conducting segments.  
     
     
         44 . A method of making a powder metal rotor component for a surface permanent magnet machine, the method comprising: 
 injecting a soft ferromagnetic powder metal from a first injection unit under heat and pressure into an inner annular region of a cylinder-shaped mold;    injecting a non-ferromagnetic powder metal from a second injection unit under heat and pressure into discrete regions within an outer annular region of the mold so as to leave spaces between each discrete region;    injecting a hard ferromagnetic powder metal from a third injection unit under heat and pressure into the spaces between the discrete regions of the outer annular region of the mold to provide an arrangement of alternating polarity permanent magnets; and    allowing the powder metals to solidify to thereby form a composite powder metal component having an inner annular magnetically conducting segment and an outer annular segment of a plurality of alternating polarity permanent magnets separated by magnetically non-conducting segments.    
     
     
         45 . The method of  claim 44 , wherein the soft ferromagnetic powder metal is Ni, Fe, Co or an alloy thereof.  
     
     
         46 . The method of  claim 44 , wherein the soft ferromagnetic powder metal is high purity iron powder with a minor addition of phosphorus.  
     
     
         47 . The method of  claim 44 , wherein the non-ferromagnetic powder metal is an austenitic stainless steel.  
     
     
         48 . The method of  claim 44 , wherein the non-ferromagnetic powder metal is an AISI 8000 series steel.  
     
     
         49 . The method of  claim 44 , further comprising mounting the composite component on a shaft to form a powder metal rotor assembly.  
     
     
         50 . The method of  claim 44 , wherein the powder metals are each combined with a binder prior to injecting.  
     
     
         51 . The method of  claim 50 , further comprising the steps of: 
 ejecting the composite component from the mold;    subjecting the composite component to debinding to provide a composite part which is essentially free of binder; and    sintering the composite part.    
     
     
         52 . A method of making a powder metal rotor component for a circumferential type interior permanent magnet machine, the method comprising: 
 injecting a soft ferromagnetic powder metal from a first injection unit under heat and pressure into an inner annular region of a cylinder-shaped mold;    injecting a non-ferromagnetic powder metal from a second injection unit under heat and pressure into discrete first regions within an outer annular region of the mold so as to leave spaces between each discrete first region;    injecting the soft ferromagnetic powder metal from the first injection unit under heat and pressure into discrete second regions between the first regions so as to leave a radially inner circumferentially extending space and optionally leaving a radially extending space through each discrete second region;    optionally injecting the non-ferromagnetic powder metal from the second injection unit under heat and pressure into the radially extending spaces;    injecting a hard ferromagnetic powder metal from a third injection unit under heat and pressure into the radially inner circumferentially extending spaces between the discrete first regions of the outer annular region of the mold to provide an arrangement of alternating polarity permanent magnets; and    allowing the powder metals to solidify to thereby form a composite powder metal component having an inner magnetically conducting segment and an outer permanent magnet segment of a plurality of alternating polarity permanent magnets separated by magnetically non-conducting barrier segments and radially embedded by magnetically conducting segments with optional intermediate magnetically non-conducting bridge segments.    
     
     
         53 . The method of  claim 52 , wherein the soft ferromagnetic powder metal is Ni, Fe, Co or an alloy thereof.  
     
     
         54 . The method of  claim 52 , wherein the soft ferromagnetic powder metal is high purity iron powder with a minor addition of phosphorus.  
     
     
         55 . The method of  claim 52 , wherein the non-ferromagnetic powder metal is an austenitic stainless steel.  
     
     
         56 . The method of  claim 52 , wherein the non-ferromagnetic powder metal is an AISI 8000 series steel.  
     
     
         57 . The method of  claim 52 , further comprising mounting the composite component on a shaft to form a powder metal rotor assembly.  
     
     
         58 . The method of  claim 52 , wherein the powder metals are each combined with a binder prior to injecting.  
     
     
         59 . The method of  claim 58 , further comprising the steps of: 
 ejecting the composite component from the mold;    subjecting the composite component to debinding to provide a composite part which is essentially free of binder; and    sintering the composite part.    
     
     
         60 . A method of making a powder metal rotor component for a spoke type interior permanent magnet machine, the method comprising: 
 injecting a non-ferromagnetic powder metal from a first injection unit under heat and pressure into an inner annular region of a cylinder-shaped mold;    injecting a soft ferromagnetic powder metal from a second injection unit under heat and pressure into discrete first regions within an outer annular region of the mold so as to leave spaces between each discrete first region;    injecting the non-ferromagnetic powder metal from the first injection unit under heat and pressure into discrete radially outer second regions between the first regions so as to leave a radially inner radially extending space between each of the adjacent first regions;    injecting a hard ferromagnetic powder metal from a third injection unit under heat and pressure into the radially extending spaces between the discrete first regions of the outer annular region of the mold to provide an arrangement of alternating polarity permanent magnets; and    allowing the powder metals to solidify to thereby form a composite powder metal component having an inner annular magnetically non-conducting segment and an outer annular segment of a plurality of alternating polarity permanent magnets separated by magnetically conducting segments and embedded by magnetically non-conducting segments.    
     
     
         61 . The method of  claim 60 , wherein the soft ferromagnetic powder metal is Ni, Fe, Co or an alloy thereof.  
     
     
         62 . The method of  claim 60 , wherein the soft ferromagnetic powder metal is high purity iron powder with a minor addition of phosphorus.  
     
     
         63 . The method of  claim 60 , wherein the non-ferromagnetic powder metal is an austenitic stainless steel.  
     
     
         64 . The method of  claim 60 , wherein the non-ferromagnetic powder metal is an AMSI 8000 series steel.  
     
     
         65 . The method of  claim 60 , further comprising mounting the composite component on a shaft to form a powder metal rotor assembly.  
     
     
         66 . The method of  claim 60 , wherein the powder metals are each combined with a binder prior to injecting.  
     
     
         67 . The method of  claim 66 , further comprising the steps of: 
 ejecting the composite component from the mold;    subjecting the composite component to debinding to provide a composite part which is essentially free of binder; and    sintering the composite part.    
     
     
         68 . A method of making a powder metal rotor component for an induction machine, the method comprising: 
 injecting a soft ferromagnetic powder metal from a first injection unit under heat and pressure into a first region of a cylinder-shaped mold to form a pattern of a plurality of equally spaced axially extending slots adjacent an exterior circumferential surface of the cylinder-shaped mold;    injecting a non-ferromagnetic powder metal from a second injection unit under heat and pressure into a plurality of discrete second regions of the mold in a radially outer portion of each slot adjacent the exterior circumferential surface, thereby forming closed slot openings; and    allowing the powder metals to solidify to thereby form a composite powder metal component having a magnetically conducting segment and a plurality of magnetically non-conducting segments enclosing slot openings.    
     
     
         69 . The method of  claim 68 , wherein the soft ferromagnetic powder metal is Ni, Fe, Co or an alloy thereof.  
     
     
         70 . The method of  claim 68 , wherein the soft ferromagnetic powder metal is high purity iron powder with a minor addition of phosphorus.  
     
     
         71 . The method of  claim 68 , wherein the non-ferromagnetic powder metal is an austenitic stainless steel.  
     
     
         72 . The method of  claim 68 , wherein the non-ferromagnetic powder metal is an MISI 8000 series steel.  
     
     
         73 . The method of  claim 68 , further comprising mounting the composite component on a shaft to form a powder metal rotor assembly.  
     
     
         74 . The method of  claim 68 , wherein the powder metals are each combined with a binder prior to injecting.  
     
     
         75 . The method of  claim 74 , further comprising the steps of: 
 ejecting the composite component from the mold;    subjecting the composite component to debinding to provide a composite part which is essentially free of binder; and    sintering the composite part.    
     
     
         76 . A method of making a powder metal rotor component for a synchronous reluctance machine, the method comprising: 
 injecting a soft ferromagnetic powder metal from a first injection unit under heat and pressure into one or more discrete first regions in a cylinder-shaped mold;    injecting a non-ferromagnetic powder metal from a second injection unit under heat and pressure into one or more discrete second regions in the mold, the discrete second regions in alternating relation with the discrete first regions; and    allowing the powder metals to solidify to thereby form a composite powder metal component having one or more magnetically conducting segments and one or more magnetically non-conducting segments.    
     
     
         77 . The method of  claim 76 , wherein the soft ferromagnetic powder metal is Ni, Fe, Co or an alloy thereof.  
     
     
         78 . The method of  claim 76 , wherein the soft ferromagnetic powder metal is high purity iron powder with a minor addition of phosphorus.  
     
     
         79 . The method of  claim 76 , wherein the non-ferromagnetic powder metal is an austenitic stainless steel.  
     
     
         80 . The method of  claim 76 , wherein the non-ferromagnetic powder metal is an AISI 8000 series steel.  
     
     
         81 . The method of  claim 76 , further comprising mounting the composite component on a shaft to form a powder metal rotor assembly.  
     
     
         82 . The method of  claim 76 , wherein the powder metals are each combined with a binder prior to injecting.  
     
     
         83 . The method of  claim 82 , further comprising the steps of: 
 ejecting the composite component from the mold;    subjecting the composite component to debinding to provide a composite part which is essentially free of binder; and    sintering the composite part.    
     
     
         84 . A method of making a powder metal rotor component for a switched reluctance machine, the method comprising: 
 injecting a soft ferromagnetic powder metal from a first injection unit under heat and pressure into a first region in a cylinder-shaped mold, the first region having a yoke and teeth configuration;    injecting a non-ferromagnetic powder metal from a second injection unit under heat and pressure into discrete second regions in the mold, the discrete second regions positioned between the teeth of the first region; and    allowing the powder metals to solidify to thereby form a composite powder metal component having a magnetically conducting segment and a plurality of magnetically non-conducting segments.    
     
     
         85 . The method of  claim 84 , wherein the soft ferromagnetic powder metal is Ni, Fe, Co or an alloy thereof.  
     
     
         86 . The method of  claim 84 , wherein the soft ferromagnetic powder metal is high purity iron powder with a minor addition of phosphorus.  
     
     
         87 . The method of  claim 84 , wherein the non-ferromagnetic powder metal is an austenitic stainless steel.  
     
     
         88 . The method of  claim 84 , wherein the non-ferromagnetic powder metal is an AISI 8000 series steel.  
     
     
         89 . The method of  claim 84 , further comprising mounting the composite component on a shaft to form a powder metal rotor assembly.  
     
     
         90 . The method of  claim 84 , wherein the powder metals are each combined with a binder prior to injecting.  
     
     
         91 . The method of  claim 90 , further comprising the steps of: 
 ejecting the composite component from the mold;    subjecting the composite component to debinding to provide a composite part which is essentially free of binder; and    sintering the composite part.    
     
     
         92 . A method of making a powder metal rotor sense ring, the method comprising: 
 injecting a powder filler material from a first injection unit under heat and pressure into an inner annular region of a cylinder-shaped mold;    injecting a non-ferromagnetic powder metal from a second injection unit under heat and pressure into discrete regions within an outer annular region of the mold so as to leave spaces between each discrete region;    injecting a hard ferromagnetic powder metal from a third injection unit under heat and pressure into the spaces between the discrete regions of the outer annular region of the mold to provide an arrangement of alternating polarity permanent magnets; and    allowing the powders to solidify to thereby form a composite powder metal component having an inner annular filler segment and an outer annular segment of a plurality of alternating polarity permanent magnets separated by magnetically non-conducting segments.    
     
     
         93 . The method of  claim 92 , wherein the non-ferromagnetic powder metal is an austenitic stainless steel.  
     
     
         94 . The method of  claim 92 , wherein the non-ferromagnetic powder metal is an AISI 8000 series steel.  
     
     
         95 . The method of  claim 92 , further comprising mounting the composite component on a shaft to form a powder metal rotor assembly.  
     
     
         96 . The method of  claim 92 , wherein the powder metals are each combined with a binder prior to injecting.  
     
     
         97 . The method of  claim 96 , further comprising the steps of: 
 ejecting the composite component from the mold;    subjecting the composite component to debinding to provide a composite part which is essentially free of binder; and    sintering the composite part.    
     
     
         98 . A composite injection molded rotor component for a rotor assembly comprising a first region of an injection molded soft ferromagnetic powder metal, a second region of an injection molded non-ferromagnetic powder metal, and optionally a third region of an injection molded hard ferromagnetic powder metal.