Abstract: Flank milling checks during a computer automated design process which may include notifying a user when a component geometry option is selected that will result in the component not being flank millable. In some examples, the user is prevented from selecting a geometry option that would result in the component not being flank millable. In some examples, devices, systems, and methods are provided for manufacturing a component with a flank milling process, in which optimized machine instructions are determined that minimize milling machine motion.

Abstract: An annularly shaped structure serves as a support and seal when pushed out on a ramp. A continuous seal in a groove is used on one or two sides to enhance sealing. A separate annular structure for sealing can be disposed adjacent to the shape having alternating longitudinal slots so that each structure is targeted to a different purpose. The structures disintegrate when made of a disintegrating material such as for example a controlled electrolytic material (CEM) so that removal of the barrier can occur after a treating operation such as fracturing where many such barriers are deployed. The slots have enlarged holes at their ends to reduce stress concentration that can lead to cracking.

Abstract: Coins, medals or casino tokens have a first side, a second side, at least one first layer made of a first material and at least one second layer made of a second material, wherein the first layer is between 10 ?m and 90 ?m, preferably 20 ?m thick. A method produces the coin wherein the coin is produced, more particularly punched, from a clad sheet-shaped composite material. A further method produces the coin wherein the coin is formed from a ring and a core arranged inside the ring. The core and the ring are punched from a clad sheet-shaped composite material and subsequently the core is inserted rotated into the ring and is fixed therein.

Abstract: A method of forming a bimetallic forging includes providing a blank comprising at least a first element and a second element of a first metal, and an insert of a second metal. A blank is configured such that the insert may be substantially encapsulated by a shell defined by the first element and the second element. The blank is forged to form a bimetallic forging including an outer portion defined by the shell, an inner portion defined by the insert, and an interface layer therebetween. In a non-limiting example, the first metal is substantially comprised of aluminum and the second metal is substantially comprised of magnesium. In a non-limiting example, the blank may be forged to form a vehicle wheel including an aluminum skin substantially encapsulating a magnesium inner portion, providing wheel with a high strength to weight ratio and improved corrosion performance.

Abstract: One embodiment of the invention includes a method comprising: placing a first insert and a second insert in a casting mold and wherein the first insert and second insert comprising a plurality of connecting post extending inbetween so that the first insert and second insert are in spaced-apart relationship in the mold, each of the first insert and the second insert comprising a first material; casting a molten second material into the casting mold so that the second material flows between the first insert and the second insert and solidifying the second material to provide a product comprising a cast over body portion with the first insert and second insert and so that the second material is mechanically locked or metallurgically bonded to the first material and so that one or both of the first insert and the second insert provides working surface for the product.

Abstract: A flow formed part includes a first end, a second end, and a side wall extending therebetween. A reinforcing member is disposed around the second end. The side wall has a profile formed along an inner surface of the side wall. The profile is adapted to be substantially burr free after windows are formed in the sidewall. A method of making a flow formed part includes the steps of disposing a preform on a tailstock, providing a plurality of rollers adjacent the tailstock, providing a mandrel having an outer surface including a plurality of alternating channels and protuberances, and causing the rollers to press the preform against the outer surface of the mandrel.

Abstract: A hard drive platter comprises a substrate that includes glassy metal. At least one magnetic layer is arranged on the substrate. The glassy metal includes at least three of zirconium, titanium, nickel, copper, and/or beryllium. A perpendicular recording system comprises the hard drive platter. A hard disk drive comprises the hard drive platter. A computer comprises the hard disk drive. A digital camera comprises the hard drive platter. A portable media player comprises the hard drive platter. An insulating layer and/or an Aluminum layer may be located between the glassy metal substrate and the at least one magnetic layer.

Abstract: A method for producing a spark plug which contains an inner conductor, an insulator surrounding the inner conductor, a spark plug body surrounding the insulator, and two electrodes forming an ignition gap. The first electrode is a center electrode connected to the inner conductor in an electrically conducting manner and the second electrode is a ground electrode connected to the spark plug body in an electrically conducting manner. An iridium component which contains more than 95 percent by weight of iridium is welded onto one of the electrodes. An iridium component that is punched out of an iridium sheet and has a thickness that is less in size than its diameter is also employed.

Abstract: Provided is a blank structure for a ring member of a bearing in which a cut target surface after stainless steel is forged has uniform surface characteristics, and highly accurate cutting processing is enabled. A blank (10), which is processed to an outer race (2) and an inner race (3) of a bearing, includes: a cylindrical portion (11, 12) formed by forging a stainless-steel material, and having an inner circumferential surface (11a, 12a) and an outer circumferential surface (11b, 12b) entirely being surface eutectic carbides fragmented beds; and a clamp portion (13) provided to one end portion side of the cylindrical portion (11, 12).

Abstract: A process is described for processing metal which includes clock rolling a metal plate until the desired thickness is achieved to form a rolled plate. Sputtering targets and other metal articles are further described.

Abstract: The disclosure relates to an industrial die cast component comprising a first side, a second side, said second side having a second side surface, an aperture opening at said second side and through said second side surface, said aperture having a respective first arcuate surface bounding a central portion of the aperture and said aperture having a respective second surface bounding a projecting portion of the aperture, said projecting portion having a closed end and an open end, said open end forming a gap in said first arcuate surface and said projecting portion closed end extending radially beyond said first arcuate surface, wherein said first arcuate surface is constructed to be engaged by a fastener.

Abstract: A method of printing on a metal surface includes steps of forming a plurality of macropores on at least a portion of a metal surface. A plurality of micropores are formed within and adjacent to the macropores. The metal surface is cleaned, and a first ink having a first color is applied to the macropores and micropores to form at least one image on the metal surface. Preferably, the ink is applied using an inkjet printer. The ink is dried. A second ink having a second color may also be applied to the metal surface and then dried. Additional inks may also be applied. A lacquer top coat may be applied to the metal surface on top of the first ink (and additional inks, if provided). Preferably, the metal surface is part of a coin.

Abstract: Very high strength single phase stainless steel coating has been prepared by magnetron sputtering onto a substrate. The coating has a unique microstructure of nanometer spaced twins that are parallel to each other and to the substrate surface. For cases where the coating and substrate do not bind strongly, the coating can be peeled off to provide foil.

Abstract: The present invention provides a tailored blank having a pair of sheet metal constituent parts each having a pair of oppositely directed major surfaces. The first constituent part has an aperture while the second constituent part has an embossment to fit the aperture. The first and second constituent parts are then secured to one another to form the tailored blank. The blank may then be subsequently formed into a component of varying material characteristics.

Abstract: The invention provides a pretreatment process for electroplating aluminum parts or strip, in which the zincating solution is modified to improve the adhesion of the subsequent electroplate to the substrate. The aluminum part or strip, such as an aluminum coin blank or strip for coin blanks, is pretreated with an improved zincate solution which provides hydroxide ions in an amount in the range of 75-175 gpl, zinc ions in an amount in the range of 15-40 gpl, nickel ions in an amount in the range of 2-10 gpl and copper ions in an amount in the range of 1.5-5 gpl. The pretreatment process preferably includes a copper strike applied from a copper cyanide strike bath at a pH in the range of 8.5-9.5, using a current density in the range of 0.1-10 A/dm2. The pretreatment and electroplating steps are preferably conducted by barrel plating, in accordance with another aspect of the invention.

Abstract: According to the invention, an inward collar is integrally shaped on the inner periphery of a cylindrical boss portion. The inward collar is raisedly shaped in the axial direction on the inner periphery of the cylindrical boss portion by a top pattern tool having an ironing punch, and a bottom pattern tool having an ironing punch. The ironing process of forming the inward collar is repeated several times by using plural dies to finish the final shape.

Abstract: There is provided a copper-base alloy useful for coinage that has a golden visual appearance. The material has a transverse electrical conductivity substantially similar to that of copper alloy C713 and when clad to a copper alloy C110 core, a transverse electrical conductivity substantially similar to both sides of a Susan B. Anthony United States dollar coin. The copper-base alloy is a copper-manganese-zinc-nickel alloy.

Abstract: An apparatus and method for welding members that are formed at least in part of aluminum. A welding assembly is constructed and arranged to position a welding material in electrically conductive relation between exterior surface portions of first and second weldable members at a location where the first and second weldable members are to be joined. The welding material assembly includes at least one welding material member mounted on a flexible carrier sheet in a predetermined arrangement with each welding material member being constructed of an electrically conductive metallic welding material capable of melting when heated by application of an electrical current. A welding method includes alternatively attaching the welding material members to a weldable member without a carrier sheet, by a welding process.

Abstract: A method of repairing cracks, imperfections, and the like in a cast article. A frusto-conical aperture is created in the article in the location of the crack or imperfection. A mating tapered plug is prepared such that the tapered plug can fit into the aperture so that the sloped side walls of the tapered plug evenly and unilaterally rest on frusto-conical sides of the aperture. The tapered plug is disposed into the aperture, and bonding material is applied between the surfaces of the tapered plug and the aperture, before or after insertion of the tapered plug into the aperture. The article is thereafter heated such that the bonding material joins the surfaces of the tapered plug and the aperture. The outer end of the tapered plug thereafter is polished so that such outer end is approximately level with the article's outer side in a refinement of the invention, the plug member may be pushed into the aperture such that a controlled interference fit is produced.

Abstract: A composite metal laminate coin planchet comprises commercially pure aluminum cladding layers metallurgically bonded to a zinc alloy core. The zinc alloy core may contain a hardening agent, such as copper or titanium, used to increase the hardness of the alloy above that of pure zinc. Trace amounts of other elements may also be present in the zinc alloy core or in the commercially pure aluminum cladding layers which do not affect their pertinent properties. The coin planchet is produced by a process comprising providing a strip or sheet of a zinc alloy core and creating a strip or sheet of composite material by metallurgically bonding commercially pure aluminum cladding layers to the zinc alloy. The coin planchets are then removed from the strip or sheet of composite material, and the remaining composite material is heated above its melting point to produce a zinc-aluminum alloy useful in die-casting.

Abstract: Ornamental jewelry is made from a composite wire for manufacturing semifinished products to be subjected to an emptying process. The wire comprises a support core (1) of a nonprecious metal that is removable by chemical or electrochemical means as well as a plurality of sections (3,4,5) of precious metal wherein at least a portion of each of said sections is radially engaged in the core.

Abstract: Bimetallic coin or a medal and a method for producing the same, which is easy to form a ring and an insert composing the coin or the medal, yet costs low, and can assure a higher joining force between the ring and the insert. The method includes processes for forming a ring by subjecting a first metal to blanking, annealing, and pickling, forming an insert thicker than the ring by subjecting a second metal to blanking and annealing, forming a thickened rim on each side, and an annular ridge around the circumferential surface of the insert, and pickling the insert, and joining the ring and the insert by causing plastic metal flow of the ridge of the insert into the inner circumferential surface of the ring through pressing the insert inserted in the center of the ring; and a bimetallic coin formed with the method.

Abstract: A bimetallic coin or blank is produced from a disc-shaped core and an annular outer component. The metal alloy material of the core is relatively harder than the metal alloy material of the outer member. The two components are bonded to each other by pressure flow of the material of the core toward and into the inner edge of the outer member. According to the invention, the peripheral edge of the core is shaped or nosed such that it extends radially outwardly. During minting, the pressure of the dies causes the material of the core to flow radially outwardly, thus causing the shaped peripheral edge of the core to penetrate into the softer material of the outer member's inner edge and, thereby, form a tongue and groove connection which resists relative axial and rotational movement between the outer member and the core. The shaping of the core also facilitates the fast speed placement of the core into the ring during the minting operation.

Abstract: The invention is directed to a rotor having a vented hat section and a method of forming the same. Such a rotor includes a hat section having a central mounting face and a cylindrical shoulder or hat wall extending axially from the mounting face to an annular peripheral section having friction surfaces disposed on opposite sides. A plurality of spaced apart vents are defined in the wall of the hat section. The vented rotor is formed by first casting a rotor to the desired configuration including at least the hat section. The initial casting is formed in such a manner that one or more depressions are provided in the radially inner surface of the wall of the hat section. These depressions do not extend through the wall of the hat section. Then, material is removed in one or more machining steps from the radially outer surface of the wall of the hat section proximate the depressions.

Abstract: The invention is directed to a method of forming a vented rotor for caliper disc brakes and the like. Such a vented rotor includes an outer friction portion having one or more ring sections with opposed friction surfaces adapted to interface with associated friction members. The vented rotor is formed by first casting a rotor to the desired configuration including at least the ring section. This initial casting is formed in such a manner that one or more depressions are provided a surface of the ring section. Then, material is removed in one or more machining steps from portions of the friction surface opposite the friction surface having the depressions, to the point that the depressions extend completely through the ring section to form the vents.

Abstract: The present invention relates to a process for producing a substrate for a thin film magnetic data storage disc, the process including the steps of: (a) providing a substrate; (b) printing a masking pattern of ink dots onto at//least a portion of the surface of the substrate by an offset printing process in which the ink to form the masking pattern is transferred from a printing plate to the substrate by an offset printing member and wherein on transfer from the printing plate to the offset member the ink fragments into the ink dots; and (c) etching the unmasked surface of the substrate thereby to texture the substrate surface. The present invention also relates to a substrate for a thin film magnetic data storage disc, the substrate having a roughened surface composed of peaks separated by valleys produced by preferential area etching, the peaks being grouped into a plurality of substantially circular sub-arrays with the sub-arrays forming a regular pattern.

Abstract: A pin type retainer for roller bearings is stamped in one piece from flat metal stock. The flat metal is first drawn into a cup shape having a broad flange around an open first end and a closed second end. The closed end provides solid support and alignment while stamping pins from the broad flange. The pins are then final shaped by swaging or machining into cross sectional forms for a variety of applications. The second end is then opened to form a ring. The pin type retainer can be modified for use with a retaining ring or a seal against contaminants. The pin type retainer can be formed from a variety of materials, including steel. An embodiment using plastic resin is also disclosed.

Abstract: A hollow metallic or metalloplastic element drawn or drawn-ironed from a decorated blank, and comprising an outer skirt decorated with an image formed from lines of dots of ink. The skirt has over its entire height which comprises zones of level h:2R at least equal to 0.5, a spacing between adjacent lines of dots of a same ink and an angle of inclination of the lines which are constant to better than a relative 1%.

Abstract: A method for machining a part with gear teeth onto an unmachined part to form drive pinion gears is disclosed. A center bore is formed at one end of the part and receives a tool center to mount the part for machining. The center bore includes a plurality of lobes which are in point contact with the lathe center, allowing adjustment between the unmachined part and the lathe center. Drive apertures are formed radially outwardly of this center bore to receive drive pins from the machine tool. Most preferably the drive apertures are slots which provide clearance, facilitating the alignment of the drive pins in the drive apertures.

Abstract: A coin blank, particularly for minting of coins and the like, is formed by an external element of metal or metal alloy having a central aperture, on the edge surface of which are cut perimetrally a series of spaced grooves, and by an internal element, of metal or metal alloy different from the former, on the edge surface of which is formed a perimetral ridge, said external and internal elements being coupled inseparably during the minting operation through the plastic flow of the material from said perimetral ridge into said grooves in said external element and through the firm fitting of the material from said ridge into the portions of the edge surface of said central aperture in said external element, provided between adjacent grooves.

Abstract: Magnetic recording media are controllably textured, particularly over areas designated for contact with data transducing heads. In connection with rigid media, the process includes polishing an aluminum nickel-phosphorous substrate to a specular finish, then rotating the disc while directing pulsed laser energy over a limited portion of the radius, thus forming an annular head contact band while leaving the remainder of the surface specular. The band is formed of multiple individual laser spots, each with a center depression surrounded by a substantially circular raised rim. The depth of the depressions and height of the rims are controlled primarily by laser power and firing pulse duration. The shape of individual laser spots can be altered by varying the laser beam inclination relative to the disc surface. On a larger scale, the frequency of firing the laser in combination with disc rotational speed controls the pattern or arrangement of laser spots.

Abstract: An outer stabilizing band or bands at the unsupported end portion of the air foils changes the configuration from an unsupported cantilevered airfoil to a baband supported airfoil during the forming of the mold and casting of the product. Such band or bands, which are later shaved away, permit dimensional stabilization and provide an outer wall for venting, fill-out, and inclusion trapping. The stabilizing band or bands are extremely thin, normally in the range of 20 to 60 one thousandths of an inch, which avoids the need for gating and minimizes the amount of machining required to remove such stabilizing band or bands from the integral airfoil and hub casting. The bands may be outside the end of the airfoil or flush with the ends of the airfoil. The procedure and method for incorporating the outer band or bands into the casting begins with the process of making the pattern. It also aids in the stabilizing of the configuration of the pattern thereby achieving more dimensional accuracy.

Abstract: The present invention is an improved disc useful as a clutch plate. The disc has a major surface, preferably a flat planar surface, and a hole, having a hole circumference, through the disc at the major surface. Preferably the disc is circular with a concentric hole. The disc further comprises at least one tooth and preferably a plurality of teeth coplanar with the major plane of the disc, and extending from the hole circumference. Each tooth has at least one, and preferably two tooth side edges extending from the hole circumference. Preferably, there are a plurality of the same shaped teeth distributed uniformly along the hole circumference. There is a tab extending at an angle, preferably perpendicular to the major plane from at least part of at least one tooth edge. Preferably a tab extends from each tooth edge.

Abstract: A substrate including a disk having a pair of opposed faces and being coined to provide a sub-micron flatness and smoothness for the disk faces. The coined disk can then be coated with a layer of storage material and used as a storage medium. Apparatus and a method for forming the coined substrate includes means for moving a plurality of disks along a predetermined path after the disks have been formed by blanking or stamping. The disks are cleaned before being coined and then stacked into containers which can be closed for transit to a point of use. The coining of the disks and the placement of the disks in containers is done under clean room conditions and the resulting coined substrates are free of flaws and defects encountered with the practice of conventional substrate forming techniques.

Abstract: A substrate including a disk having a pair of opposed faces and being coined to provide a sub-micron flatness and smoothness for the disk faces. The coined disk can then be coated with a layer of storage material and used as a storage medium. Apparatus and a method for forming the coined substrate includes means for moving a plurality of disks along a predetermined path after the disks have been formed by blanking or stamping. The disks are cleaned before being coined and then stacked into containers which can be closed for transit to a point of use. The coining of the disks and the placement of the disks in containers is done under clean room conditions and the resulting coined substrates are free of flaws and defects encountered with the practice of conventional substrate forming techniques.

Abstract: A safe having a wall comprising spaced steel plates, a sheathing layer between the plates consisting of hard non-metallic grains of e.g., boron carbide, silicon carbide, boron nitride, diamonds, ceramic oxides and hard metallic grains of e.g., cast iron, metal carbides, nitrides, borides, and silicides, said grains being bound together and to said plates by a hard solder mass having a copper or nickel base. The sheathing layer contains 30-70% by volume of said non-metallic grains (having a grain size of 5 to 20 mm) and metallic grains (having a grain size of 1 to 6 mm) and from 70% to 30% of said hard solder. The ratio of said non-metallic to said metallic grains is 2-4 parts to 1 part by volume. A method for making the sheathing layer is also disclosed.

Abstract: The present disclosure relates to an apparatus and a method for deforming sheet metal plates and more particularly aluminium and steel plates. The objectives of this disclosure are realized by laminating a plate of sheet metal in juxtaposed and parallel strips. This method allows for the formation of spherical surfaces having a variable curvature. These strips are oriented according to predetermined axes according to the expected result.

Abstract: The disclosure relates to a novel shell such as used in the manufacture of can ends, and to a method and tools for making such a shell. A non-circular blank having rounded corners is cut from thin metal. The blank is oblong in a direction transverse to the grain of the metal. A first set of tools separates the blanks and forms a substantially flat central panel and an upward-extending chuck wall about the edge of the panel to produce a partially formed shell. The junction area between said panel and said chuck wall has a relatively large radius of curvature at this time. A second set of tools forms in the blank a lip extending outward from the upper end of the chuck wall and generally parallel to said panel; then the panel and the chuck wall are separately gripped, followed by relative movement between the panel and the chuck wall while wrapping the junction area around a forming punch to form a panel wall in said junction area extending upward from the inner part of said chuck wall.

Abstract: A flat, smooth material, e.g., metal sheet, suitable for use as a disc substrate for applying a recording media thereto for data storage devices, and a method of making same, are disclosed. The flat and smooth substrate is formed by applying sufficient pressure to opposite surfaces of the material to achieve the desired flatness and smoothness prior to finishing. Subsequent finishing may be used to remove any zone of roughness which may be present in the surfaces of the disc resulting from the pressing step. In one embodiment, the pressure step may be applied before finishing the disc perimeters.

Abstract: Disclosed is a gas turbine disk made from powder metal, wherein the bore has improved fatigue life compared to conventional articles because the bore is formed from a fine fraction of powder separated from a lot of conventional powder metal suitable for hot isostatic compaction. The outer and rim portions of the disk, which are less prone to fatigue failure, are made from the remainder of the lot but nonetheless have no more limited performance from that resulting when a unitary unseparated powder lot is used. Improved bore fatigue properties result because the coarse fatigue failure-causing nonmetallic inclusions are biased into the outer portions of the disk where they do not have adverse effect.

Abstract: The disclosure relates to a novel shell such as used in the manufacture of can ends, and to a method and tools for making such a shell. A non-circular blank having rounded corners is cut from thin metal. The blank is oblong in a direction transverse to the grain of the metal. A first set of tools separates the blanks and forms a substantially flat central panel and an upward-extending chuck wall about the edge of the panel to produce a partially formed shell. The junction area between said panel and said chuck wall has a relatively large radius of curvature at this time. A second set of tools forms in the blank a lip extending outward from the upper end of the chuck wall and generally parallel to said panel; then the panel and the chuck wall are separately gripped, followed by relative movement between the panel and the chuck wall while wrapping the junction area around a forming punch to form a panel wall in said junction area extending upward from the inner part of said chuck wall.

Abstract: An aureate coin, coin blank, medallion, medallion blank, token or token blank has a coin-shaped core with opposed faces and a peripheral side edge and of mintable metallic material. An electroplated coating of copper and tin completely encases the core and provides a golden appearance. The electroplated coating contains from about 8 to about 16% tin by weight and has a thickness of from about 10 to about 150 .mu.m.

Abstract: A protective overcoating is disclosed for a magnetic alloy thin-film recording disc that includes a magnetic alloy film formed on a disc-shaped substrate or coated substrate. The protective overcoating is formed by first sputtering onto the magnetic medium an interfacial layer of titanium, and then sputtering onto the titanium a layer of carbon. The sputtered carbon provides wear-resisting lubricity, while the titanium interface promotes the adhesion of the sputtered carbon to the magnetic medium of the recording disc.

Abstract: A coin blank for the coining of coins, medals and like products, obtained by the forced joining of two metal parts, each of them being of different metal or metal alloy, one forming the internal central part and the other the external perimetrical part, said forced joining of said two component parts being carried out, in a definitive and inseparable way, preferably upon the minting operation.

Abstract: A molybdenum disc suitable for the use as a semiconductor. The disc has a thickness of about 0.5 to several mm and is coated with a noble metal that is applied to the molybdenum in a layer thickness of 0.02.mu. via an intermediate layer of chromium having a layer thickness of 0.5 to 10.0.mu..

Abstract: A base plate for magnetic recording disc is produced by coating thin metal layers containing no impurities for forming defects by an anodizing treatment on one or both sides of a discoid substrate made of a metal such as aluminum or an aluminum alloy or from a plastic by a dry process, and anodizing the thin metal layers so as to form anodized film from the surfaces of the thin metal layers to a certain depth while the portions contacting to the substrate are retained not anodized.

Abstract: A substrate for a magnetic recording disk employs an annular core of synthetic material having thin metal foils bonded to opposite faces, the metal foils serving to receive a magnetic recording material to form a magnetic recording structure. The inner surfaces of foils which are bonded to the core faces have applied thereto a thin, soft, deformable layer such as copper to prevent irregularities in the core faces from affecting the outer surfaces of the metal foils.

Abstract: A jewellery post has an elongated member with a longitudinally extending passage adjacent one end, and a plug of bonding material within the passage adjacent this end. The bonding plug is a sliding fit in the passage and has a length which is short compared to the length of the tubular member.

Abstract: A wheel disc and method of manufacture wherein disc blanks are punched from a continuous length of strip material in an enchelonned nested pattern so as to minimize stock scrap and wastage. The disc blanks are substantially flat and have a peripheral edge defined by a series of concentric convex crowns separated from each other by concave recesses. The disc blanks are each formed to a final cross sectional configuration which optimizes the relationship of disc strength to weight. The disc is welded into a drop center wheel rim to provide a wheel assembly for pneumatic tubeless tires.

Abstract: A blank suitable for minting to form a coin or similarly disc-shaped article has an appropriately disc-shaped steel core completely encased by a copper coating electroplated thereof. The blank is produced by electroplating a copper coating onto an appropriately disc-shaped steel core such that the copper coating completely encases the steel core.