Search Results for seizure

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.

Friction and wear are important when considering the operation and efficiency of components and mechanical systems. Among the different types and mechanisms of wear, adhesive wear is very serious. Adhesion results in a high coefficient of friction as well as in serious damage to the contacting surfaces. In extreme cases, it may lead to complete prevention of sliding; as such, adhesive wear represents one of the fundamental causes of failure for most metal sliding contacts, accounting for approximately 70% of typical component failures. This article discusses the mechanism and failure modes of adhesive wear including scoring, scuffing, seizure, and galling, and describes the processes involved in classic laboratory-type and standardized tests for the evaluation of adhesive wear. It includes information on standardized galling tests, twist compression, slider-on-flat-surface, load-scanning, and scratch tests. After a discussion on gear scuffing, information on the material-dependent adhesive wear and factors preventing adhesive wear is provided.

Surface damage from sliding contact is related to the adhesion of mating surfaces in contact. This article describes the methods for evaluation of surface damage caused by sliding contact. It defines adhesive wear in terms of asperity, cold welding, galling, scuffing, seizure, and wear coefficient. The article discusses various galling testing methods, such as button-on-block galling test, pin-on-flat galling test, and threaded connection galling test. It provides an overview of fretting wear that occurs between two tight-fitting surfaces subjected to a cyclic, relative motion of extremely small amplitude. The article also reviews the fretting rig for investigating fretting wear.

This article describes the basic concepts of the complex factors that influence the forces, power, and stresses in machining. It provides an overview of the models of orthogonal (that is, two force) machining of metals as they are useful for understanding the basic mechanics of machining and can be extended for modeling of the production processes. The article discusses stresses on the shear plane, stresses distributions on the rake face, uniform stresses on the rake face, and nonuniform stress distributions on the rake face. It also examines the specific power consumption in turning, drilling, and milling operations. The article concludes with a section on the factors affecting specific power.

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.

Case hardening involves various methods and each method has unique characteristics and different considerations in the selection of steels This article reviews the various grades of carburizing steels, carbonitriding steels, nitriding steels, and steels for induction, or flame hardening. This review is based on their process characteristics, compositions, applications, and mechanical properties, which help in selecting steels for case hardening.

This article reviews the factors influencing carburization to improve wear resistance of steel, such as operating temperature, cost, production volume, types of wear, and design criteria. It details the types of wear, namely abrasive wear and adhesive wear. The article discusses the characteristics of carburized steels that affect wear resistance, including hardness, microstructure, retained austenite, and carbides. It also describes the processing considerations for carburization of titanium.

Surface hardening improves the wear resistance of steel parts. This article focuses exclusively on the methods that involve surface and subsurface modification without any intentional buildup or increase in part dimensions. These include diffusion methods, such as carburizing, nitriding, carbonitriding, and austenitic and ferritic nitrocarburizing, as well as selective-hardening methods, such as laser transformation hardening, electron beam hardening, ion implantation, selective carburizing, and surface hardening with arc lamps. The article also discusses the factors affecting the choice of these surface-hardening methods.

Pumps and compressors are representative fluid machineries, which are indispensably important industrial equipment for water supply systems, chemical processing and reactions, and fluid power systems. This article addresses friction, lubrication, and wear of components in several types of machines such as positive displacement pumps including hydraulic pumps, turbo-pumps including centrifugal pumps, vacuum pumps, and compressors including the positive displacement type and turbo type.