Search Results for special-purpose bearing steels

Rolling-element bearings, whether ball bearings or roller bearings with spherical, straight, or tapered rollers, are fabricated from a wide variety of steels. This article discusses the production process, characteristics, nominal compositions, and types of bearing steels. These include standard bearing steels, such as high-carbon bearing steels and carburizing bearing steels; and special-purpose bearing steels, such as high-temperature service bearing steels and corrosion-resistant bearing steels.

Bearing steels, which include high-carbon and low-carbon types, can be divided into service-based classes, such as normal service, high-temperature service, and service under corrosive conditions. This article discusses the importance of matching the hardenability and quenching of a bearing steel. It also discusses the typical microstructure of a high-carbon through-hardened bearing, and shows typical case and core microstructures in carburized bearing materials. Apart from a satisfactory microstructure, which is obtained through the proper combination of steel grade and heat treatment, the single most important factor in achieving high levels of rolling-contact fatigue life in bearings is the cleanliness, or freedom from harmful nonmetallic inclusions, of the steel. Alloy conservation and a more consistent heat-treating response are benefits of using specially designed bearing steels. The selection of a carburizing steel for a specific bearing section is based on the heat-treating practice of the producer, either direct quenching from carburizing or reheating for quenching, and on the characteristics of the quenching equipment.

The choice of heat treatment depends on the service requirements of a given bearing and how the bearing will be made. This article describes the design parameters, material characteristics required to sustain performance characteristics, metallurgical properties, and dimensional stability. It also provides a description of various extensively-used heat treatment processes, namely, carburizing, carbonitriding, induction surface hardening, and nitriding associated with various bearings. In addition, the article explores the factors to be considered in selecting a process and explains why it is optimum for a specific application.

Hot-rolled steel bars and other hot-rolled steel shapes are produced from ingots, blooms, or billets converted from ingots or from strand cast blooms or billets and comprise a variety of sizes and cross sections. Most carbon steel and alloy steel hot-rolled bars and shapes contain surface imperfections with varying degrees of severity. Seams, laps, and slivers are probably the most common defects in hot-rolled bars and shapes. Another condition that could be considered a surface defect is decarburization. Hot-rolled steel bars and shapes can be produced to chemical composition ranges or limits, mechanical property requirements, or both. Hot-rolled carbon steel bars are produced to two primary quality levels: merchant quality and special quality. Merchant quality is the least restrictive descriptor for hot-rolled carbon steel bars. Special quality bars are employed when end use, method of fabrication, or subsequent processing treatment requires characteristics not available in merchant quality bars.

Tin is a soft, brilliant white, low-melting metal that is most widely known and characterized in the form of coating. This article discusses the primary and secondary production of tin and explains the uses of tin in coating, namely tinplating, electroplating, and hot dip coatings. It presents a short note on pure (unalloyed) tin and uses of tin in chemicals. The article also covers the compositions and uses of tin alloys which include solders, pewter, bearing alloys, alloys for organ pipes, and fusible alloys. It goes on to discuss the other alloys containing tin including battery grid alloys, type metals, copper alloys, dental alloys, cast irons, titanium alloys, and zirconium alloys. Finally, it presents a short note on the applications of tin powder and corrosion resistance of tin.

This article summarizes some general alloy groupings by application or major characteristics. The groupings include cast rotor, general-purpose, elevated-temperature, wear-resistant, moderate-strength, high-strength, and high-integrity die casting alloys and cast aluminum alloys bearings. A table lists selected applications for aluminum casting alloys.

Wire rod is a semifinished product rolled from billet on a rod mill and is used primarily for the manufacture of wire. Steel wire rod is usually cold drawn into wire suitable for further drawing; for cold rolling, cold heading, cold upsetting, cold extrusion, or cold forging; or for hot forging. The article explains these operations, along with the several recognized quality and commodity classifications applicable to steel wire rods. The heat treatments commonly applied to steel wire rod, either before or during processing into wire, include annealing, spheroidize annealing, patenting, and controlled cooling. When the end product must be heat treated, the heat treatment and mechanical properties should be clearly defined. Carbon steel rods are produced in various grades or compositions: low-carbon, medium-low-carbon, medium-high-carbon, and high-carbon steel wire rods. Rod for the manufacture of carbon steel wire is produced with manufacturing controls and inspection procedures intended to ensure the degree of soundness and freedom from injurious surface imperfections necessary for specific applications. This article also describes the various quality descriptors applicable to the rods as well as standard qualities and commodities available in alloy steel wire rod.

A sliding bearing (plain bearing) is a machine element designed to transmit loads or reaction forces to a shaft that rotates relative to the bearing. This article discusses the properties of bearing materials. It provides information on bearing material systems: single-metal systems, bimetal systems, and trimetal systems. The article describes the designations, nominal compositions, mechanical properties, and applications of various sliding bearing alloys: tin-base alloys, lead-base alloys, copper-base alloys, aluminum-base alloys, silver-base alloys, zinc-base alloys, additional metallic materials, nonmetallic materials. It describes casting processes, powder metallurgy processes, and electroplating processes. The article also discusses the selection criteria for bearing materials.

Selective plating, also known as brush plating, differs from traditional tank or bath plating in that the workpiece is not immersed in a plating solution (electrolyte). Instead, the electrolyte is brought to the part and applied by a handheld anode or stylus, which incorporates an absorbent wrapping for applying the solution to the workpiece (cathode). This article focuses on the selective plating systems that include a power pack, plating tools, anode covers, specially formulated plating solutions, and any auxiliary equipment required for the particular application. It provides a detailed account of the applications of selective plating, with examples. The article describes the advantages, limitations, key process elements, and health and safety considerations of selective plating. It also includes the most important industrial, government, and military specifications.

A sliding bearing (plain bearing) is a machine element designed to transmit loads or reaction forces to a shaft that rotates relative to the bearing. This article explains the role of wear damage mechanisms in the design and selection of bearing materials, and its relationship with bearing material properties. Sliding bearings are commonly classified by terms that describe their application; they also are classified according to material construction, as single-metal, bimetal, or trimetal sliding bearings. The article further provides detailed tabular data on the designation and composition of the following types of bearing materials: tin-base alloys, lead-base alloys, copper-base alloys, and aluminum-base alloys. It also briefly discusses the following types of bearing materials: zinc-base alloys, silver-base alloys, gray cast irons, cemented carbides, and nonmetallic bearing materials.

This article briefly describes the nomenclature, alignment and geometrical considerations, and functional and application requirements of a die set. The die set consists of the shank, guide posts, guide bushings, the punch, and die holders. The article illustrates plate flatness and parallelism in the die set. The testing for abrasion, seizure, and endurance in the die set are discussed briefly. The article concludes with information on die-set recommendations.

This article discusses different types of mechanical fasteners, including threaded fasteners, rivets, blind fasteners, pin fasteners, special-purpose fasteners, and fasteners used with composite materials. It describes the origins and causes of fastener failures and with illustrative examples. Fatigue fracture in threaded fasteners and fretting in bolted machine parts are also discussed. The article provides a description of the different types of corrosion, such as atmospheric corrosion and liquid-immersion corrosion, in threaded fasteners. It also provides information on stress-corrosion cracking, hydrogen embrittlement, and liquid-metal embrittlement of bolts and nuts. The article explains the most commonly used protective metal coatings for ferrous metal fasteners. Zinc, cadmium, and aluminum are commonly used for such coatings. The article also illustrates the performance of the fasteners at elevated temperatures and concludes with a discussion on fastener failures in composites.

Horizontal centrifugal casting is used to cast parts having an axis of revolution. This article discusses the operations of three types of horizontal casting machine: the flanged shaft machine, the horizontal roller-type machine, and the double-face plate machine. It provides information on expendable and permanent molds used for centrifugal casting. The parameters and operations of the horizontal centrifugal casting process, including pouring and solidification, as well as the applications are described.

Rolling-element bearings, also called rolling bearings and antifriction bearings, tend to have very low friction characteristics compared to plain bearings or simple sliding bearings. This article discusses the types of rolling-element bearings, namely, ball bearings and roller bearings. It provides information on the bearing component materials. The article describes the lubrication requirements and lubrication methods, namely, elastohydrodynamic lubrication and grease lubrication. It reviews the adjustment factors influencing fatigue life of the bearing. The article also provides information on bearing load ratings, standard bearing geometries, rolling bearing friction factors, and wear and its control methods. It concludes with a discussion on damage modes of bearings.

Hot-rolled steel bars and other hot rolled steel shapes are produced from ingots, blooms, or billets converted from ingots, or from strand cast blooms and billets, and comprise a variety of sizes and cross sections. This article provides a brief discussion on mechanical properties, quality descriptors and chemical compositions of hot-rolled steel bars, cold-finished steel bars, steel wire rod and steel wire. It contains tables that provide size tolerances for cold-finished carbon steel bar and cold-finished alloy steel bar.

This article discusses the processing, properties, and applications of various grades of lead and lead-base alloys with the aid of several tables and illustrations. It lists the Unified Numbering System (UNS) designations for various pure lead grades and lead-base alloys grouped according to nominal chemical composition. The properties of lead that make it useful in a wide variety of applications are also discussed. The largest usage of lead is in the lead acid storage batteries (in the grid plates, posts, and connector straps). Other applications include ammunition; cable sheathing; cast products such as type metals, terneplates, and foils; and building construction materials. Lead is also used as an alloying element in steel and in copper alloys to improve machinability and other characteristics. In many applications, lead is combined with stronger materials to make structures that have the best qualities of both materials such as the plumbum series.

This article provides an overview of two major classes of bearings: rolling bearings and sliding, or plain, bearings. It reviews the experimental data resulted from testing of rolling and sliding bearing materials with illustration. The article presents a table that summarizes rolling contact fatigue test methods that ASTM published in STP 771. It also describes the role of lubrication in the bearings.

Nitriding is a general term for all processes based on the addition of nitrogen to the surface of steel. When carbon is added along with the nitrogen, the process is called nitrocarburizing. This article provides a detailed discussion on the functional and structural properties of nitrided layers. It describes the structural changes on the surface of carbon steels, alloy steels, and austenitic stainless steels. The article explains the effects of the various nitriding processes, namely, gaseous nitriding, plasma nitriding, gaseous nitrocarburizing, and salt bath nitrocarburizing, on the structure and properties of nitrided layers.

Machining is a term that covers a large collection of manufacturing processes designed to remove unwanted material, usually in the form of chips, from a workpiece. This article discusses the basic classes of machining operations, including conventional, abrasive, and nontraditional, and outlines the type of costs incurred by the process. It describes the types of machining equipment, including general-purpose machine tools, production machining systems, and computer numerically controlled machining systems. The article lists the common classes of metallic work materials, in order of decreasing machinability. It also shows the range of dimensional and surface finish tolerances in graphical form that can be achieved using various machining processes under general machining conditions.

Babbitting is a process by which relatively soft metals are bonded chemically or mechanically to a stronger shell or stiffener which supports the weight and torsion of a rotating, oscillating, or sliding shaft. This article focuses on workpiece preparation and babbitting methods. Prior to casting, the workpiece must be scrupulously prepared by various cleaning, fluxing, and tinning steps. Babbitting of bearing shells can be accomplished by three methods, namely, static babbitting, centrifugal casting, and metal spray babbitting.