Abstract:
An improvement in apparatus and methods of making electrical machines, utilizing a combination of additive manufacturing techniques to create, in particular, small, high efficiency stators, but also useful for making complex rotor structures.

Description:
BACKGROUND 
       [0001]    The present invention relates to the production of electric machines such as induction motors or generators. Known induction motors use multiple windings of conductive wire within a magnetic case to form a stator section and apply alternating current to these windings to cause a rotor within the stator section to turn. Induction generators work in the opposite way, where the rotor is turned and induces current in the windings. In both induction motors and generators, a magnetizing current is supplied to the rotor by the stator. This comes about due to slip between the rotor coils, often a “squirrel cage” coil configuration, and the rotating field produced by the stator. If the rotor turns faster than the stator field, mechanical power from the rotor is converted to real electrical power in the stator, and vice versa. 
       SUMMARY 
       [0002]    A method of laminating a stack of sheet material, wherein the sheet material is cut and unwanted portions are removed, and additive manufacturing devices are used to build up structures of conducting and insulating materials within slots manufactured in at least some of the sheet materials in the stack. Further, the invention includes a stack of laminated sheet materials with additively manufactured portions, where adjacent sheets include conductive portions which are in electrical contact with one another. In some embodiments, this stack of laminated sheet materials forms an induction machine. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0003]      FIG. 1  is a perspective view of a machine used to create electrical machines such as induction machines. 
           [0004]      FIG. 2A  is a cross-sectional view of a laser engineered net shaping device using powder material. 
           [0005]      FIG. 2B  is a side view of an electron beam melting device using a metal wire. 
           [0006]      FIG. 3  is a perspective view of a machine used to create induction machines, with several layers of the induction machine completed. 
           [0007]      FIG. 4  is a perspective cutaway of a stator. 
           [0008]      FIG. 5  is a cross-sectional view of an additively manufactured component, showing a pattern of additively manufactured conductive windings encased in additively manufactured insulator regions encased in sheet material. 
           [0009]      FIG. 6  is an exploded view of multiple layers of a laminated stack, showing a simplified winding structure. 
       
    
    
     DETAILED DESCRIPTION 
       [0010]    In general, the present invention allows for high efficiency induction machines to be constructed that have efficiency comparable to or greater than the efficiencies obtained by permanent magnet machines, without the use of rare earth materials. Induction machines, including induction motors and induction generators, convert electrical energy to or from mechanical energy by rotating a rotor slightly slower or faster, respectively, than a rotating magnetic field produced by alternating currents applied to stator windings. In the case of an induction motor, the rotating magnetic field generated by these windings causes the rotor to rotate and deliver useful mechanical power at a rotor angular speed slightly less than the angular speed of the stator field. 
         [0011]      FIG. 1  is a perspective view of rapid manufacturing system  10 .  FIG. 1  further shows sheet material supply and take-up rolls, and a portion of sheet material on the working surface. The sheet material is coated on both sides with an insulator, for example iron oxide or glass material that has a coefficient of thermal expansion similar to that of the sheet material. Rapid manufacturing system  10  includes movable support  14 , laser  16 , minor  18 , movable optical head  20 , heated roller  22 , guides  24 , laser additive manufacturing apparatus  26 , and electron beam melting apparatus  28 . Also shown are sheet material  30 , supply roll  32 , and take-up roll  34 . 
         [0012]    Movable support  14  is any solid foundation capable of holding a stack of laminated layers (not shown). Movable support  14  may include a sacrificial, disposable or removable portion, such that objects which are laminated onto support may be removed from rapid manufacturing system  10  more easily. Movable support  14  is attached to an actuator (not shown) which may be used to set the desired vertical position of movable support  14 . After each sheet layer is cut to the required shape and the conductor material and insulator material are deposited, the movable support moves down by the thickness of the sheet, a new sheet is positioned over the movable support, and the process is repeated. 
         [0013]    Laser  16  is any laser suitable for cutting and sintering operations. For example, in many embodiments, a carbon dioxide laser may be used. Mirror  18  is any minor which will direct laser radiation. Preferably, mirror  18  is adjustable, such that the radiation incident upon minor  18  may be selectively aimed. Movable optical head  20  is a device capable of directing incident radiation onto the surface of sheet material  30 . For example, movable optical head  20  may include a minor, a lens, or other optics for focusing a laser beam. Further, movable optical head  20  may move in the region above movable support  14 , for example using an x-y positioning stage. Multiple lasers may be used, for example, for separate cutting and sintering operations, with corresponding mirrors and movable optical heads. In addition, an electron beam head can be used instead of a movable laser head. The surrounding environment is dependent on the type of additive manufacturing energy source. 
         [0014]    Heated roller  22  is heated and movable above movable support  14 . In the embodiment shown in  FIG. 1 , heated roller  22  is a cylinder. In alternative embodiments, heated roller may be a heated arc or knife blade laminator. Guides  24  as shown in  FIG. 1  are rollers, but in alternative embodiments may be any fixed or rotatable arcuate structures. Heated roller  22  may also be integrated with an ultrasonic device to increase the efficiency of joining the laminates with the insulator layers. 
         [0015]    Laser additive manufacturing apparatus  26  may be any laser additive manufacturing (LAM) apparatus recognized by those skilled in the art. For example, laser additive manufacturing apparatus  26  may be a Laser Engineered Net Shaping (LENS) apparatus, Direct Metal Laser Sintering (DMLS) apparatus, Laser Powder Deposition (LPD) apparatus, or Selective Laser Sintering (SLS) apparatus for polymers or metals. Additive manufacturing apparatus  26  may either include its own laser for softening, melting or sintering pulverant material, or laser  16  may be used to soften, melt or sinter the pulverant material (not shown) deposited by laser additive manufacturing apparatus  26 . Electron beam melting apparatus  28  may be any electron beam melting apparatus recognized by those skilled in the art. For example, electron beam melting apparatus  28  may be an Electron Beam Melting (EBM) apparatus or Electron Beam Wire (EBW) apparatus. 
         [0016]    Sheet material  30  is a flexible sheet of any material which is desirable for building into a three-dimensional structure. For example, sheet material  30  may be a sheet of high silicon steel alloy. Sheet material  30  may include a diffusion layer, such as a layer of glass, iron oxide, polyamide, silicone, phenolic or polyether ether ketone (PEEK). Supply roll  32  is a cylindrical core with sheet material  30  wrapped around the cylindrical core. Similarly, take-up roll  34  is a cylindrical core with sheet material  30  wrapped around the cylindrical core. 
         [0017]    Movable support  14  is free to move towards or away from sheet material  30  between supply roll  32  and take-up roll  34 . Typically, movable support  14  has a range of motion that is at least as large as the height of the desired stack of laminated layers (not shown). In alternative embodiments, movable support  14  may stay in a fixed position while rollers  24  are moved relative to movable support  14 . 
         [0018]    Radiation (a laser beam) from laser  16  radiates towards minor  18 , which directs the radiation towards movable optical head  20 . Minor  18  is not necessary in all embodiments, and persons of ordinary skill in the art will recognize that alternatives, such as fiber optics, may be substituted to transmit radiation from laser  16  to movable optical head  20 . Alternatively, movable optical head  20  may not be necessary in embodiments where minor  16  directs radiation towards its ultimate target. Movable optical head  20  is capable of moving into positions where it can direct radiation towards laser additive manufacturing apparatus  26  or sheet material  30 . Heated roller  22  is movable across sheet material  30 , and may be used to apply heat and pressure to layers of a laminated stack (not shown) to cause binding of layers by inter-diffusion of adjacent diffusion layers. 
         [0019]    Additive manufacturing apparatus  26  is movable along the surface of sheet material  30  opposite from movable support  14 . Additive manufacturing apparatus  26  may selectively deposit pulverant material. Electron beam melting apparatus  28  may also be used to selectively deposit pulverant material. Electron beam melting apparatus  28  is also movable about the surface of sheet material  30  opposite movable support  14 . In alternative embodiments, additive manufacturing apparatus  26  and electron beam melting apparatus  28  may be substituted; for example, alternative embodiments may have two (or more) additive manufacturing apparatuses and/or two (or more) electron beam melting apparatuses. 
         [0020]    Sheet material  30  is rolled into both supply roll  32  and take-up roll  34 . Sheet material  30  is guided by guides  24 , and passes above movable support  14 . Additionally, sheet material  30  passes under movable head  20 , additive manufacturing apparatus  26 , electron beam melting apparatus  28 , and heated roller  22 . Supply roll  32  and take-up roll  34  are rotatable to advance sheet material  30  across movable support  14  or the laminated stack (see  FIG. 3 ). It will be understood by those skilled in the art that in alternative embodiments, sheet layers may be formed by stamping, laser deposition, electron beam deposition, or other additive or subtractive manufacturing methods. The alternative of generating the laminate by using the laser additive manufacturing process and depositing high silicon steel powder alloy will allow the fabrication of controlled grain-oriented silicon steel laminates for magnetic structures, which will lead to decreasing core loss especially for high frequency or high harmonic designs. 
         [0021]    The embodiment shown in  FIG. 1  is used to create layers of components such as induction machines. Sheet material  30  is advanced to at least partially cover movable support  14 . Laser  16  is used to cut an outer periphery of a layer. Radiation from laser  16  is reflected off of minor  18  in the direction of movable optical head  20 . Movable optical head  20  redirects the radiation towards a desired target. Laser additive manufacturing apparatus  26  is used to selectively deposit pulverant material by applying powder to selected regions, then using radiation from laser  16  to sinter or melt the pulverant material in desired locations. Electron beam melting apparatus  28  may also be used to selectively deposit material. Electron beam melting apparatus  28  melts metal wire stock or pulverant material in desired locations using an electron beam. Heated roller  22  is used to apply heat and pressure to a cut portion of sheet material  30  with deposited material from laser additive manufacturing apparatus  26  or electron beam melting apparatus  28 . 
         [0022]    The combination of additive manufacturing processes such as laser additive manufacturing apparatus  26  or electron beam melting apparatus  28  with laser cutting of sheet material allows for rapid manufacturing of objects with multiple materials throughout the body of the object. By repeatedly cutting and building up layers using the processes shown in  FIG. 1 , a component may be built which is very difficult or even impossible to create using traditional manufacturing processes. 
         [0023]      FIG. 2A  shows an example of a laser additive manufacturing apparatus  26 . Laser additive manufacturing apparatus  26  includes pulverant material reservoir  202 , two pulverant material dispensers  204 , and laser guide  206 . Pulverant material reservoir  202  is any container suitable for holding pulverant material  208 . Pulverant material dispensers  204  may be opened or closed to selectively restrict flow of material. Laser guide  206  is shown as a channel in pulverant material reservoir  202 . Pulverant material  208  may be any pulverant material suitable for use in additive manufacturing, such as fine powders of conductors or insulators. For example, pulverant material  208  may be copper powder, or green glass powder. Laser radiation path  210  is a line along which movable optical head  20  may direct laser radiation. 
         [0024]    Pulverant material reservoir  202  is connected to pulverant material dispensers  204 , which selectively restrict or allow flow of pulverant material  208 . Laser radiation path  210  passes through laser guide  206  and intersects the path of pulverant material  208  which is dispensed from pulverant material dispenser  204 . 
         [0025]    In use, laser additive manufacturing apparatus  26  as shown in  FIG. 2A  moves in tandem with movable optical head  20 . Typically, laser  16  (shown in  FIG. 1 ) and movable optical head  20  are used for additional functions, such as cutting or in other additive manufacturing processes. Therefore, laser additive manufacturing apparatus  26  need only be positioned in tandem with movable optical head  20  while additive manufacturing is occurring. In alternative embodiments, pulverant material  208  may be deposited by laser additive manufacturing apparatus  26  before movable optical head  20  sinters or melts pulverant material  208 . In those embodiments, it is not necessary for laser additive manufacturing apparatus  26  to include laser guide  206 , nor is it necessary for laser additive manufacturing apparatus  26  to move in tandem with movable optical head  20 . In alternate embodiments, additional pulverant material reservoirs containing additional types of pulverant material may be used. 
         [0026]    Laser additive manufacturing apparatus  26  is one type of apparatus which may be used to build up structures within each of the sheets in a laminated stack of sheets. After an outer periphery and interior apertures are lased and unwanted sheet material is removed, laser additive manufacturing apparatus  26  may be used to build up any type of meltable or sinterable structure, such as insulating coatings or sections of conductive windings. 
         [0027]      FIG. 2B  shows an example of electron beam melting apparatus  28 . Electron beam melting apparatus  28  as shown in  FIG. 2B  includes electron beam source  250 , electron beam  252 , spool  254 , and meltable material  256 . Electron beam source  250  is a device which is capable of producing high energy electrons and focusing them into electron beam  252 . For example, electron beam source  250  may be a wire filament carrying a current, a high voltage accelerating circuit, and a series of magnets directing excited electrons through a metal foil window. 
         [0028]    Spool  254  is unwound such that an end of meltable material  256  transects electron beam  252  as it emanates from electron beam source  250 . Where electron beam  252  transects meltable material  256 , meltable material  256  melts. Electron beam melting apparatus  28  may be moved such that melted portions of meltable material  256  are deposited in desired locations. In alternative embodiments, meltable material  256  may be delivered in powder form to the desired location. 
         [0029]    By moving electron beam melting apparatus  28  to deposit melted portions of meltable material  256  in desired locations, electron beam melting apparatus  28  may be used as another way to additively manufacture features in each layer of a stack of a laminated stack of sheet materials. For example, electron beam melting apparatus  28  may be used to deposit insulating coatings or sections of conducting windings. 
         [0030]      FIG. 3  shows rapid manufacturing system  310  partway through building a component. Rapid manufacturing system  310  includes movable optical head  320 , heated roller  322 , guides  324 , first LAM apparatus  326 , and second LAM apparatus  328 . First LAM apparatus  326  and second LAM apparatus  328 , as shown in  FIG. 3 , are both LENS type additive manufacturing devices. As shown in  FIG. 3 , first LAM apparatus  326  is used in conjunction with laser radiation directed by movable optical head  320  to sinter insulating material. Likewise, as shown in  FIG. 3 , second LAM apparatus  328  is used in conjunction with laser radiation directed by movable optical head  320  to sinter conductive material. Also shown are sheet material  330 , supply roll  332 , take-up roll  334 , and laminated stack  336 . Laminated stack  336  is a stack of layers, wherein each layer is made up of a combination of sheet material  330 , insulated deposited by first LAM apparatus  326 , and conductive material deposited by second LAM apparatus  328 . Also shown are hole outlines  312 . Each hole outline  312  is the laser cut outline of material which has been cut from sheet material  330 , including the layer, apertures, and waste material. 
         [0031]    Movable optical head  320  receives laser radiation from a laser source (not shown) and directs it towards desired locations on sheet material  330 . Rapid manufacturing system  310  has cut hole outlines  312  into sheet material  330 . Sheet material  330  passes between movable support  314  and movable optical head  320 . Movable support  314  may also move away from sheet material  330  such that laminated stack  336  is directly beneath sheet material  330  and fills part of the space between movable support  314  and sheet material  330 . First LAM apparatus  326  and second LAM apparatus  328  are arranged on the same side of sheet material  330  as movable optical head  320 . Heated roller  322  is also arranged on the same side of sheet material  330  as movable optical head  320 . Guides  324  set the position of sheet material  330 . 
         [0032]    As sheet material  330  is advanced from supply roll  332  to above movable support  314  to take-up roll  334 , movable optical head  320  directs laser radiation toward the hole outlines  312  in sheet material  330 . Within these lased outlines, movable optical head  320  may cut additional features, such as an outer periphery of a layer as well as apertures for desired features within the layer. Some portion of the material within each outline is removed and either discarded or recycled. Such removal is typically accomplished using pressurized inert gas. First LAM device  326  and second LAM device  328  are used to deposit sinterable or meltable materials in desired locations. For example, first LAM device  326  may be used to deposit a sinterable insulating material within apertures cut by laser radiation emanating from movable optical head  320 . The insulating material deposited by first LAM device  326  need not fill the entirety of apertures cut by laser radiation emanating from movable optical head  320 . Rather, it is sometimes desirable to additively manufacture additional features of a different material. For example, second LAM device  328  may deposit conductive material within the apertures cut by laser radiation emanating from movable optical head  320 . 
         [0033]    Each time a layer of sheet material  330  is cut and additive manufacturing is complete, heated roller  322  laminates the layer to an underlying structure and movable support  314  moves away from sheet material  330  by the roughly the thickness of one layer. The thickness of each layer is set by the thickness of sheet material  330 . For example, many sheet materials will be between 0.10 and 0.25 mm thick. The amount of movement of movable support  314  may be different from the thickness of sheet material  330 , if lamination by heated roller  322  causes any change to the thickness of the layer. The layer becomes the topmost part of laminated stack  336 , and also the physical support for the next layer that is constructed. After lamination and movement of movable support  314 , supply roll  332  and take-up roll  334  rotate to advance a different portion of sheet material  330  over movable support  314  and laminated stack  336 . 
         [0034]      FIG. 3  shows how a laminated stack can be constructed using multiple additive manufacturing devices in one apparatus. Using multiple additive manufacturing devices in one apparatus allows for construction of components which were previously difficult or impossible to construct. 
         [0035]      FIG. 4  shows component  400 , which includes additively manufactured features  408  within sheet material  430 . Component  400  may be any component that is built using two or more additive manufacturing materials within apertures in a laser-cut structure. For example, component  400  may be an induction machine such as an induction motor or an induction generator, wherein the laser-cut structure is a magnetic material such as silicon steel, and two additive manufacturing materials are a PEEK insulator disposed along the border of laser-cut apertures in the silicon steel and copper disposed along the inside border of the PEEK. Additively manufactured features  408  are typically segments of additively manufactured conductive material insulated by additively manufactured insulating material. 
         [0036]    Additively manufactured features  408  are typically arranged within apertures in sheet material  430  such that conductive additively manufactured features are aligned with conductive additively manufactured features in at least one adjacent layer of laminated stack  436 . Insulating additively manufactured features are typically arranged to prevent electrical contact between conductive additively manufactured features and sheet material  430 , either in the same layer of laminated stack  436  or in adjacent layers of laminated stack  436 . 
         [0037]    In order to create an induction machine, windings are frequently used to generate magnetic fields when current is applied. By choosing appropriate arrangements of additively manufactured features  408  in each layer of laminated stack  436 , component  400  may include windings of conductive material which are insulated from sheet material  430 . Additionally, additively manufactured features  408  may have their topology optimized to reduce interference and eddy currents as a result of current flowing through such windings. 
         [0038]    Additively manufactured components such as the one shown in  FIG. 4  have numerous advantages over similar components made using alternative manufacturing techniques. Induction motor components may be additively manufactured which use materials more efficiently and optimize the position of windings within the induction machine more precisely. By optimizing the design of magnetic, insulating, and conductive materials, it is possible to eliminate the use of rare earth materials in the motor, while maintaining efficiencies greater than those presently achieved in devices which do include rare earth materials. Further, it is possible to make induction machines which are more lightweight and smaller than their counterparts that are not made using multiple additive manufacturing processes. 
         [0039]      FIG. 5  shows the surface of one layer in a laminated stack.  FIG. 5  includes additively manufactured features  508 , each of which includes conductive material  562  and insulating material  564 , within sheet material  566 . As in previously described embodiments, conductive material  562  is any conductive material, and preferably one with low resistivity such as copper. Insulating material  564  may be any insulating material which prevents electrical contact between conductive material  562  and sheet material  566 . For example, insulating material  564  may be a high-melting-temperature polymer, or an oxide. 
         [0040]    Additively manufactured features  508  are arranged throughout apertures cut in sheet material  566 . Within each aperture is an insulating coating made of insulating material  564 , and within at least some of those insulating coatings are pockets within which conductive material  562  is disposed. In some embodiments, sheet material may be arranged between groups of additively manufactured features. In other embodiments, such as the one shown in  FIG. 5 , it is not necessary for interstices  568  to be present. Further, the shape of insulating and conductive materials may vary. For example, a large aperture could be present in sheet material  566 , and insulating material  564  could be arranged within the aperture and include a honeycomb, grid, or other arrangement of pockets within which conductive material is disposed. 
         [0041]    In some embodiments, the structure of additively manufactured features  508  may be selected such that, in combination with additively manufactured features in other layers (not shown), the conductive portions combine to form intertwined conductor paths similar to Litz wire or other alternating current (AC) resistivity-reducing topologies. In many embodiments, insulating material  564  is present between each conductive material  562  and sheet material  566 . 
         [0042]      FIG. 5  demonstrates the high packing density which is possible using additive manufacturing. Traditionally, induction machine windings are created using wrappings of conductive wire which has been coated with an insulator. Such windings are much less dense than the windings that can be additively manufactured. Shaped and oriented individual windings may be included in additively manufactured components such as the one shown in  FIG. 5 , such as Litz wire and end wrapping topologies. 
         [0043]      FIG. 6  is an exploded view of a stack of laminated layers. Component  600  is made of several layers of sheet material  630 , some of which contain additively manufactured features  608 . Conductive material  662  fills pockets formed by insulating material  664  and the underlying layer. 
         [0044]    The layers of conductive material  662 , insulating material  664 , and sheet material  630  are arranged such that conductive material  662  in each layer is electrically connected to conductive material  662  in at least one adjacent layer. Furthermore, insulating material  664  is arranged such that there is no electrical connection between conductive material  662  and sheet material  630 . 
         [0045]    The exploded view in  FIG. 6  shows a simplified set of windings. In the diagram shown, the windings are twisted loops, but in other embodiments the loops may not be twisted. By providing untwisted loops, and disposing large quantities of interconnected loops, an induction machine stator may be constructed. 
         [0046]    Improved stators may be created using additive manufacturing by placing these windings closer together than was previously possible with wire windings, and by optimizing the topology of the windings and their dimensions. Further, the relative thickness of the sheet metal or magnetic material may be decreased and it can be manufactured at the same time as the windings. These improvements mean a thinner magnetic portion with less eddy currents, less material used, and higher efficiencies. 
         [0047]    While the invention has been described with reference to an exemplary embodiment(s), it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment(s) disclosed, but that the invention will include all embodiments falling within the scope of the appended claims. 
       DISCUSSION OF POSSIBLE EMBODIMENTS 
       [0048]    The following are non-exclusive descriptions of possible embodiments of the present invention. 
         [0049]    A method including (a) producing a layer of a sheet material including an aperture over a movable support, wherein the layer has a thickness and an outer periphery; (b) depositing an insulating material in a first portion of the aperture, adjacent to the outline of the aperture, to form an insulating coating with one or more pockets; (c) depositing a conductive material in the one or more pockets; (d) applying heat and pressure to the layer; (e) lowering the movable support by the thickness of the layer; and (f) repeating steps (a)-(e) to form a laminated stack of layers that define a component. 
         [0050]    The method of the preceding paragraph can optionally include, additionally and/or alternatively, any one or more of the following features, configurations and/or additional components: 
         [0051]    producing the layer of the sheet material includes positioning the sheet material over the movable support, laser cutting the sheet material to define the outer periphery of the layer, removing the sheet material outside the outer periphery of the layer, laser cutting the outline of the aperture in the layer, and removing the sheet material within an outline of the aperture; 
         [0052]    laser welding the outer periphery of the layer; 
         [0053]    depositing all of the sheet material, the insulating material, and the conductive material necessary to form the component; 
         [0054]    depositing the conductive material in the one or more pockets further includes depositing the conductive material such that the conductive material in the one or more pockets is electrically connected to the conductive material in a pocket of at least one adjacent layer of the laminated stack of layers, and is electrically insulated from the sheet material by the insulating coating; 
         [0055]    the sheet material includes steel coated with a diffusion layer; 
         [0056]    the diffusion layer includes at least one of: glass, iron oxide, PEEK, phenolic, polyamide, and silicone; 
         [0057]    the conductive material is copper; 
         [0058]    the insulating material is one of the group consisting of: ceramic insulators, polymeric insulators, and insulating oxides; 
         [0059]    laminating includes melting the diffusion layers of adjacent pieces of the sheet material; 
         [0060]    depositing the insulating material includes using laser additive manufacturing to sinter the insulating material; 
         [0061]    depositing the conducting material includes using laser additive manufacturing to sinter the conducting material; 
         [0062]    depositing the conducting material includes using electron beam melting to melt the conducting material; and 
         [0063]    removing the sheet material is accomplished using pressurized gas. 
         [0064]    An apparatus includes a stack of laminated layers, at least one of the layers including a sheet material including at least one aperture; an insulating material arranged in a first portion of the aperture, adjacent to the sheet material; and a conducting portion arranged in a second portion of the aperture, adjacent to the insulating material, wherein the conducting portion of each layer is arranged in electrical contact with the conducting portion of at least one adjacent layer. 
         [0065]    The apparatus of the preceding paragraph can optionally include, additionally and/or alternatively, any one or more of the following features, configurations and/or additional components: 
         [0066]    the conducting portions of the stack of laminated layers form conductive windings of an electric machine; 
         [0067]    the apparatus does not contain any rare-earth materials; and 
         [0068]    the topology of the conductive windings are optimized for use as an induction machine. 
         [0069]    A method of forming a component of an induction machine includes forming a plurality of layers of steel sheet with apertures for conductive windings, forming by additive manufacturing an electrically conductive winding layer within the aperture surrounded by an electrically insulating layer so that the winding layer is electrically insulated from the steel sheet, and laminating a plurality of sheets with the apertures aligned to form a component body of laminated steel sheets having insulated conductive windings extending through the component body. 
         [0070]    The method of the preceding paragraph can optionally include the feature that the induction machine is one of an induction motor or an induction generator.