Search Results for babbitts

An investigation of wear and failure of babbitt bushes was completed in this study. The results showed that wear at dry sliding of babbitt obtained by plasma spraying was less than that of babbitt in the as-cast state and after a deformation heat treatment. The failure of babbitt bushes was caused by a simultaneous and interrelated exhibition of fatigue and wear processes that depend considerably on cohesion strength between the bush and the bearing base and accumulation of defects on the contact surface between the bush and the shaft.

This article discusses the classification of sliding bearings and describes the major groups of soft metal bearing materials: babbitts, copper-lead bearing alloys, bronze, and aluminum alloys. It provides a discussion on the methods for fluid-film lubrication in bearings. The article presents the variables of interest for a rotating shaft and the load-carrying capacity and surface roughness of bearings. Grooves and depressions are often provided in bearing surfaces to supply or feed lubricant to the load-carrying regions. The article explains the effect of contaminants in bearings and presents the steps for failure analysis of sliding bearings. It also reviews the factors responsible for bearing failure with examples.

A mechanical part, which supports the moving part, is termed a mechanical bearing and can be classified into rolling (ball or roller) bearings and sliding bearings. This article discusses the failures of sliding bearings. It first describes the geometry of sliding bearings, next provides an overview of bearing materials, and then presents the various lubrication mechanisms: hydrostatic, hydrodynamic, boundary lubrication, elastohydrodynamic, and squeeze-film lubrication. The article describes the effect of debris and contaminant particles in bearings. The steps involved in failure analysis of sliding bearings are also covered. Finally, the article discusses wear-damage mechanisms from the standpoint of bearing design.

Metallography is an important component of failure analysis. In the case of a liquid metal embrittlement (LME) failure it is usually conclusive if a third phase constituent can be formed inside of the cracks after failure. In the case where it is necessary to characterize the third phase material, one can use various x-ray spectrographic techniques in conjunction with a scanning electron microscope (SEM). This study describes those metallographic and SEM analysis techniques for determining the mode of failure for a locomotive traction motor by LME.

Metal-induced embrittlement is a phenomenon in which the ductility or fracture stress of a solid metal is reduced by surface contact with another metal in either liquid or solid form. This article summarizes the characteristics of solid metal induced embrittlement (SMIE) and liquid metal induced embrittlement (LMIE). It describes the unique features that assist in arriving at a clear conclusion whether SMIE or LMIE is the most probable cause of the problem. The article briefly reviews some commercial alloy systems where LMIE or SMIE has been documented. It also provides some examples of cracking due to these phenomena, either in manufacturing or in service.

Metal-induced embrittlement is a phenomenon in which the ductility or the fracture stress of a solid metal is reduced by surface contact with another metal in either the liquid or solid form. This article summarizes some of the characteristics of liquid-metal- and solid-metal-induced embrittlement. This phenomenon shares many of these characteristics with other modes of environmentally induced cracking, such as hydrogen embrittlement and stress-corrosion cracking. The discussion covers the occurrence, failure analysis, and service failures of the embrittlement. The article also briefly reviews some commercial alloy systems in which liquid-metal-induced embrittlement or solid-metal-induced embrittlement has been documented and describes some examples of cracking due to these phenomena, either in manufacturing or in service.

This article provides a background of friction-bearing failures due to overheating. The failures of locomotive axles caused by overheated traction-motor support bearings are discussed. The article also describes liquid-metal embrittlement (LME) in steel. It examines the results of various axle studies, with illustrations and concludes with information on the simulation of the LME mechanism.

Cavitation damage of diesel engine cylinder liners is due to vibration of the cylinder wall, initiated by slap of the piston under the combined forces of inertia and firing pressure as it passes top dead center. The occurrence on the anti-thrust side may possibly result from bouncing of the piston. The exact mechanism of cavitation damage is not entirely clear. Two schools of thought have developed, one supporting an essentially erosive, and the other an essentially corrosive, mechanism. Measures to prevent, or reduce, cavitation damage should be considered firstly from the aspect of design, attention being given to methods of reducing the amplitude of the liner vibration. Attempts have been made to reduce the severity of attack by attention to the environment. Inhibitors, such as chromates, benzoate/nitrite mixtures, and emulsified oils, have been tried with varying success. Attempts have been made to reduce or prevent cavitation damage by the application of cathodic protection, and this has been found to be effective in certain instances of trouble on propellers.

This article focuses on the visual or macroscopic examination of damaged materials and interpretation of damage and fracture features. Analytical tools available for evaluations of corrosion and wear damage features include energy dispersive spectroscopy, electron probe microanalysis, Auger electron spectroscopy, secondary ion mass spectroscopy, and X-ray powder diffraction. The article discusses the analysis and interpretation of base material composition and microstructures. Preparation and examination of metallographic specimens in failure analysis are also discussed. The article concludes with a review of the evaluation of polymers and ceramic materials in failure analysis.

Examination of a damaged component involves a chain of activities that, first and foremost, requires good observation and documentation. Following receipt and documentation, the features of damage can be recorded and their cause(s) investigated, as this article briefly describes, for typical types of damage experienced for metallic components. This article discusses the processes involved in visual or macroscopic examination of damaged material; the interpretation of fracture features, corrosion, and wear damage features; and the analysis of base material composition. It covers the processes involved in the selection of metallurgical samples, the preparation and examination of metallographic specimens in failure analysis, and the analysis and interpretation of microstructures. Examination and evaluation of polymers and ceramic materials in failure analysis are also briefly discussed.

This article outlines the basic steps to be followed and the range of techniques available for failure analysis, namely, background data assembling, visual examination, microfractography, chemical analysis, metallographic examination, electron microscopy, electron microprobe analysis, X-ray techniques, and simulations. It also describes the steps for analyzing the data, preparing the report, preservation of evidence, and follow-up on recommendations.

This article discusses failures in shafts such as connecting rods, which translate rotary motion to linear motion, and in piston rods, which translate the action of fluid power to linear motion. It describes the process of examining a failed shaft to guide the direction of failure investigation and corrective action. Fatigue failures in shafts, such as bending fatigue, torsional fatigue, contact fatigue, and axial fatigue, are reviewed. The article provides information on the brittle fracture, ductile fracture, distortion, and corrosion of shafts. Abrasive wear and adhesive wear of metal parts are also discussed. The article concludes with a discussion on the influence of metallurgical factors and fabrication practices on the fatigue properties of materials, as well as the effects of surface coatings.

In addition to failures in shafts, this article discusses failures in connecting rods, which translate rotary motion to linear motion (and conversely), and in piston rods, which translate the action of fluid power to linear motion. It begins by discussing the origins of fracture. Next, the article describes the background information about the shaft used for examination. Then, it focuses on various failures in shafts, namely bending fatigue, torsional fatigue, axial fatigue, contact fatigue, wear, brittle fracture, and ductile fracture. Further, the article discusses the effects of distortion and corrosion on shafts. Finally, it discusses the types of stress raisers and the influence of changes in shaft diameter.