Search Results for rolling-contact wear

This article discusses the physical signs of rolling-contact wear (RCW). It lists the major considerations in gear design and describes the mechanisms of RCW. The article provides a guide to rolling-contact fatigue (RCF) testing methods. It explains the steps involved in the processes of RCF and RCW.

Rolling-contact fatigue (RCF) is a surface damage process due to the repeated application of stresses when the surfaces of two bodies roll on each other. This article briefly describes the various surface cracks caused by manufacturing processing faults or blunt impact loads on ceramic balls surfaces. It discusses the propagation of fatigue cracks involved in rolling contacts. The characteristics of various types of RCF test machines are summarized. The article concludes with a discussion on the various failure modes of silicon nitride in rolling contact. These include the spalling fatigue failure, the delamination failure, and the rolling-contact wear.

A major cause of failure in components subjected to rolling or rolling/sliding contacts is contact fatigue. This article focuses on the rolling contact fatigue (RCF) performance and failure modes of overlay coatings such as those deposited by physical vapor deposition, chemical vapor deposition, and thermal spraying (TS). It provides a background to RCF in bearing steels in order to develop an understanding of failure modes in overlay coatings. The article describes the underpinning failure mechanisms of TiN and diamond-like carbon coatings. It presents an insight into the design considerations of coating-substrate material properties, coating thickness, and coating processes to combat RCF failure in TS coatings.

Wear is mechanically-induced surface damage that results in the progressive removal of material. Because different types of wear occur in machinery, many different types of wear tests have been developed to evaluate its effects on materials and surface treatments. This article provides an explanation on mechanisms, forms (sliding, impact, and rolling) and the causes of wear. It describes the wear measuring methods, including the mass loss method, wear width method, and scar depth method. The units used to report wear vary with type of wear and with the purpose for which the data are to be used. Listing the considerations of tribosystem analysis, the article provides information on selection of ASTM wear test methods grouped by wear type. The article concludes by tabulating the testing geometries and parameters that are commonly controlled and reported when conducting wear tests.

Rolling-contact fatigue (RCF) is a common failure mode in components subjected to rolling or rolling-sliding contact. This article provides a basic understanding of RCF and a broad overview of materials and manufacturing techniques commonly used in industry to improve component life. A brief discussion on coatings to improve surface-initiated fatigue and wear is included, due to the similarity to RCF and the increasing criticality of this failure mode. The article presents a working knowledge of Hertzian contact theory, describes the life prediction of rolling-element bearings, and provides information on physics and testing of rolling-contact fatigue. Processes commonly used to produce bearings for demanding applications are also covered.

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.

The surface of irons and steels can be hardened by introducing nitrogen (nitriding), nitrogen and carbon (nitrocarburizing), or nitrogen and sulfur (sulfonitriding) into the surface. This article lists the principal reasons for nitriding and nitrocarburizing, and summarizes the typical characteristics of nitriding processes along with a general comparison of carburizing processes in a table. It describes the two most common nitriding methods: gas nitriding and ion (plasma) nitriding. The article discusses the wear behavior of nitrided layers and the wear resistance of selected steels. Rolling-contact fatigue (RCF) occurs in rolling contacts such as bearings, rolls, and gears. The article provides a discussion on rolling-contact fatigue of nitrided steels for aerospace bearing components.

Rolling-element bearings use rolling elements interposed between two raceways, and relative motion is permitted by the rotation of these elements. This article presents an overview of bearing materials, bearing-load ratings, and an examination of failed bearings. Rolling-element bearings are designed on the principle of rolling contact rather than sliding contact; frictional effects, although low, are not negligible, and lubrication is essential. The article lists the typical characteristics and causes of several types of failures. It describes failure by wear, failure by fretting, failure by corrosion, failure by plastic flow, failure by rolling-contact fatigue, and failure by damage. The article discusses the effects of fabrication practices, heat treatment and hardness of bearing components, and lubrication of rolling-element bearings with a few examples.

This article discusses the tests designed specifically to evaluate the adhesion, friction, and wear behavior of various material systems. It tabulates the characteristics of common types of wear and mechanical surface damage. The article also considers the displaying and analyzing of adhesion, friction, and wear test data. It concludes with a description of devices used for testing adhesion, friction, and wear.

Transition metal dichalcogenides (TMD) are solid lubricant materials, specifically, intrinsic solid lubricants, whose crystal structure facilitates interfacial sliding/shear to achieve low friction and wear in sliding contacts and low torque in rolling contacts. This article provides information on sliding friction and wear behavior of unbonded, bonded, and vapor-deposited pure and composite MoS 2 and WS 2 coatings. It discusses the rolling-torque behavior and applications of vapor-deposited pure and composite MoS 2 and WS 2 coatings. The article concludes with information on various forms of TMD lubrication, namely, oils, greases, microparticle and nanoparticle additives.

This article discusses the composition, properties and applications of bearing steels. It focuses on the typical wear modes that rolling-element bearings experience: contact fatigue wear, abrasive wear, adhesive wear, and corrosive wear. The article provides information on reliability factor and ABMA and ISO environmental factors.

Current understanding of polishing wear involves a combination of abrasive, plastic flow, and tribochemical wear. This article explains these mechanisms and the correlation between them. Some explanations about practical polishing wear control, applications, and future prospects are also given. This article discusses the influence of size and number of wear particles on polishing at three abrasive wear modes. These include cutting, wedge forming, and plowing. The article concludes with information on applications and prospects of polishing wear control.

This article presents typical wear applications for a variety of cast iron grades in a table. In general, wear is classified according to three major types: adhesive (frictional) wear (sliding and rolling) caused by contact of one metallic surface with another; abrasive wear caused by contact with metallic (shots, swarf) or nonmetallic abrasive materials; and erosive wear. The article discusses general wear characteristics of gray iron, compacted gray iron, and ductile iron. It provides information on the brake lining chemistry effects, graphite morphology effects, normal cast iron wear, local cast iron wear, and external abrasive effects on brake drums and disk brake rotors made of gray cast iron. The article concludes with a discussion on the application of cast iron for grinding balls.

Contact fatigue is a surface-pitting-type failure commonly found in ball or roller bearings. This article discusses the mechanisms of contact fatigue found in gears, cams, valves, rails, and gear couplings. It discusses the statistical analysis of rolling contact bearing-life tests. The article concludes with information on various approaches that improve the contact fatigue resistance of rolling contact systems.

Tribology is the science and technology of interacting surfaces in relative motion. This article describes in detail the basic structural, operational, and interaction parameters of a tribosystem. The interaction parameters, which characterize the action of the operational parameters on the structural components in the system, consist of three important aspects: contact parameters, friction parameters, and wear parameters. These three aspects embody the complex mechanisms and relationships between the constituents of a tribosystem. The article concludes with information on the selection criteria of a material for wear applications.

This article considers the main characteristics of wear mechanisms and how they can be identified. Some identification examples are reported, with the warning that this task can be difficult because of the presence of disturbing factors such as contaminants or possible additional damage of the worn products after the tribological process. Then, the article describes some examples of wear processes, considering possible transitions and/or interactions of the mechanism of fretting wear, rolling-sliding wear, abrasive wear, and solid-particle erosion wear. The role of tribological parameters on the material response is presented using the wear map concept, which is very useful and informative in several respects. The article concludes with guidelines for the selection of suitable surface treatments to avoid wear failures.

This article begins with the basic concept of friction and with the general approaches that can be used to control or minimize it. It focuses on the factors influencing rolling friction: surface topography, composition, subsurface microstructure, and lubrication conditions. The article reviews the microscopic mechanisms generating friction. It concludes by discussing the three components of rolling friction: microslip at the interface, anelastic hyteresis losses, and surface roughness.

Rolling is the process of reducing the thickness or changing the cross section of a workpiece by compressive forces applied through a set of rolls. This article emphasizes flat rolling and illustrates basic flat-rolling process used to reduce the thickness of a rectangular cross section. It provides a discussion on hot rolling, cold rolling, and warm rolling, as well as lubrication in rolling. The article reviews the lubrication for iron-base and nickel-base materials, light metals, copper-base alloys, and titanium alloys. It discusses the wear mechanism in rolling: abrasion, adhesion, and fatigue, as well as oxidative and corrosive wear. Surface modification techniques, such as hardening by induction heat treating, weld overlay, thermal spray coating, coating via physical vapor deposition (PVD), and laser surface treatment, are also discussed for improving roll service life.