Magnetics Technical Publications
201. Soft Magnetic Material for A.C. Applications: Soft magnetic material using powder metallurgical techniques are gaining wide spread use in motors, compressors and other rotating devices. A high-density soft magnetic material (AncorLam) was developed with excellent induction and coercive force. A green density of 7.55g/cm3 at 13-tons/cm2, coercivity of 310 A/m, resistivity of 8000 micro-ohm cm, and a green strength of 100MPa are achieved. This presentation will discuss application of this material in motors, in general, operating at frequencies above 400 Hertz.
150. The Effect of Processing and Density on PM Soft Magnetic Properties: With the trend towards more widespread use of automotive electric systems such as electric power steering, new opportunities exist for PM soft magnetic alloys. These applications require high density for magnetic properties and precision. To meet density, precision and geometry complexity requirements, secondary operations are usually employed, which degrade magnetic properties. Annealing can be utilized for recovery of the magnetic properties, but with the potential for dimensional changes. Through the use of an advanced binder system, higher densities with subsequent increases in magnetic properties can be achieved in a single compaction step. The influence of secondary operations, processing methods such as the use of an advanced binder system and annealing are presented for Fe, Fe-P and Fe-Ni materials.
144. Unique Stainless Steel Materials and Processing for High Strength with Reduced Magnetic Performance: A new automotive part was designed having property requirements incorporating high yield and tensile strengths with good ductility, while at the same time requiring reduced magnetic performance. This combination of properties precludes the use of iron and low alloy materials because of their intrinsic magnetic response. In an effort to satisfy both requirements, type 200 stainless steel powders were prepared and processed into both mechanical property test specimens and magnetic toroids. Processing of the compacted samples was optimized to give the required strength characteristics with required minimal magnetic response. This paper will detail the types of stainless materials utilized and unique processing developed to accomplish these conflicting requirements. The mechanical and magnetic properties will be presented.
130. Effect of Processing and Materials Selection on PM Part Magnetic Properties: The increased usage of electromagnetic components in the drive train of cars and SUV's often impose conflicting requirements of good magnetic properties with high strength and high hardness. Traditionally, PM soft magnetic materials utilizing iron-phosphorus alloys are characterized by good magnetic performance but relatively low strength, hardness. Thus to achieve the mechanical property and dimensional requirements it is often necessary to perform secondary operations such as sizing, coining, or machining often in combination with a separate heat treatment operation. This paper will focus on the effects of various secondary operations on the mechanical and magnetic properties of soft magnetic materials in an actual component. Additionally, data will be presented on a higher strength magnetic material and the potential for this material to replace existing soft magnetic materials and possibly eliminate some of the secondary operations intended to increase the strength of the actual component.
118. Processing of Ferro-Phos-Containing Mixes in Low Hydrogen Atmospheres: Ferrophosphorus-containing premixes with iron are used extensively in magnetic applications. Recent trends toward reducing cost necessitate reduction of hydrogen content in the sintering atmosphere. This reduction of hydrogen leads to occasional brittle fracture in parts made from ferrophosphorus mixes. The objective of this investigation is to develop a robust powder that could be used in low hydrogen-containing sintering atmosphere. A design of experiments was developed to include residual elements and oxygen level in the ferrophosphorus powder. The results suggest controlling the oxygen in the ferrophosphorus is critical in achieving high impact energies while sintering in low hydrogen atmospheres. Addition of a minute amount of graphite can improve the impact strength of the otherwise low impact material.
96. PM High Strength Magnetic Alloys: Sintered PM magnetic materials are characterized by good DC magnetic performance with relatively low yield and tensile strengths, typically the tensile strengths are less than 50,000 psi. This inherently low strength of the common magnetic alloys results from the use of pure iron or iron phosphorus alloys. This low strength often limits the potential applications for sintered PM magnetic materials. Described in this paper are PM alloys that have tensile strengths approaching 70,000 psi (480 MPa) in the as sintered condition with tensile ductility approaching 10% and having magnetic properties equal to the pure iron and / or iron phosphorus alloys. These alloys are intended for higher strength, magnetic applications. A comparison to the standard PM magnetic alloys will be made.
61. Application of High Performance Material Processing - Electromagnetic Products: The use of powder metallurgy (PM) parts in AC applications is limited by the inability to reduce the total core loss of the PM components to levels achieved with conventional laminations. The use of iron powder polymer composites has proven successful in high frequency applications such as ignition coils and high-speed motors. Broader application of PM in AC applications will require a metedal that will provide superior magnetic performance at low frequencies. This paper will discuss the use of high performance materials for DC applications (in particular, alloys of iron and silicon) as well as the use of insulated powders for both high and low frequency applications.
47. The Manufacture of Electromagnetic Components by the Powder Metallurgy Process: The powder metallurgy process provides the ability to manufacture net shape parts from a variety of materials in a cost effective manner. A market segment that has exhibited the ability to take advantage of powder metallurgy's flexibility has been in electromagnetic applications. This area has shown significant growth in the past decade that should continue for the foreseeable future. This paper will discuss materials and processes that have proven successful in several electromagnetic applications. Both sintered materials for DC type applications and insulated materials for AC applications will be reviewed along with appropriate processing techniques for each. Specific applications for both materials will be presented.
44. Powder Metallurgy Materials for AC Magnetic Applications: Ancorsteel Insulated Powders provide the ability to utilize ferrous powder metallurgy materials in alternating magnetic field applications. These materials, unlike sintered components, offer the ability to control eddy current generation at high frequencies. The development process involved in the evolution of these materials is reviewed along with magnetic and physical properties. Potential part applications are presented with special emphasis placed on utilizing powder metallurgy's unique shape making capabilities.
36. Powder Metallurgy in Electromagnetic Applications: New product and process advances have expanded the potential for powder metallurgy growth into a variety of new applications. The ANCORDENSE™ process has enabled high density powder metallurgy parts to be attained cost effectively. Increases in density improve the magnetic performance of powder mettallurgy materials. In addition, a new process for producing iron powder with a then thermoplastic coating has been developed. Compacts produced from this material exhibit excellent high frequency magnetic properties. The role that these advances in powder metallurgy play in electromegnetic applications is discussed.
29. Effects of Powder Properties and Processing on Soft Magnetic Performance of 400-Series Stainless Steel Parts: With the advent of growth in soft magnetic applications suitable to Powder Metallurgy, powder manufacturers parts fabricators and end users of such parts must gain a better understanding of the relationships between powders, processing and the ultimate performance of soft magnetic PM parts. Studies have been conducted and valuable data extracted on the subjects of pure iron, iron-phosphorus, iron-silicon and prealloyed iron-nickel alloys as they relate to magnetic properties. With the identification of applications requiring corrosion resistance as well as mechanical and magnetic properties, including the Anti-lock Brake System (ABS) tone wheel, industry is investigating ferritic stainless steel solutions. This study represents an effort to provide some initial answers to questions regarding the "real world" capability of PM production of high quality, ferritic stainless steel parts that exhibit excellent magnetic properties.
23. High Density Processing of High Performance Ferrous Materials: Density is an predominant factor in the performance of powder metallurgy components. Methods such as double press/double sinter, copper infiltration and powder forging have been employed to provide higher densities than traditional single press and sinter operations; however, their widespread use is constrained by cost and geometry considerations. A commercially proven method for obtaining single compaction/single sinter densities in the 7.25 to 7.55 g/cm3 range by means of the patented ANCORDENSE™ technology is introduced. Conventional compaction pressures and sintering temperatures, typically not exceeding 50 tsi or 2300°F, respectively, are utilized. Resulting properties for several high performance materials are presented. Test results indicate that the ANCORDENSE process is a cost effective method of providing high density parts with outstanding physical properties. The process is shown to be applicable to a wide variety of high performance materials. Additionally, significant improvements in green strength and ejection forces are realized.
19. Effects of Processing and Materials on the Soft Magnetic Performance of Powder Metallurgy Parts: Soft magnetic properties of PM parts are influenced by materials and processing. This paper will review the magnetic properties of several iron-based materials along with how various processing steps influence magnetic properties. In particular, density, sintering temperature, sintering time and sintering atmosphere effects will be examined. Special attention will be paid to the influence that sintering conditions have on chemistry and the resulting effects on magnetic properties. Materials investigated in the study include pure iron and combinations of iron, phosphorus, silicon and nickel.