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Motor Bearing
Published in Wei Tong, Mechanical Design and Manufacturing of Electric Motors, 2022
There are two major types of rolling bearings, distinguished mainly by the rolling-element shape: ball bearings and roller bearings. According to the configuration of the bearing rings, ball bearings are further classified as deep-groove ball bearings and angular contact ball bearings. On the other hand, according to the shape of the rollers, roller bearings are classified as cylindrical, spherical, tapered, and needle roller bearings. To distinguish bearings from their functions, the bearing can be divided into radial bearings, which withstand primarily radial loads and axial loads to a certain extent, and thrust bearings, which withstand only axial loads.
Introduction to Successful Root Cause Failure Analysis (RCFA)
Published in Randy Riddell, Practical Root Cause Failure Analysis, 2022
A hidden failure might be one that is a defect in the part, but it is still functioning, at least for the moment. The failure is hidden as far as the function of the asset is concerned but is a real defect on the part. An example here might be a bearing defect. The function of a bearing is to support the load while allowing the rotation of the shaft. That still happens with a bearing defect but eventually it will turn into a functional failure if allowed to go on for long enough. A lubrication breakdown that is not known is another hidden failure. A part with a fatigue crack growing is a hidden failure. These things may or may not be known or could have the ability to be known by some technology. This would be the area of the failure curve where failure is occurring, but it has not been detected yet.
Bearings and Lubrication
Published in Ansel C. Ugural, Youngjin Chung, Errol A. Ugural, Mechanical Engineering Design, 2020
Ansel C. Ugural, Youngjin Chung, Errol A. Ugural
The goal of a bearing is to provide relative positioning and rotational freedom while transmitting a load between two parts, commonly a shaft and its housing. The object of lubrication is to reduce the friction, wear, and heating between two surfaces moving relative to each other. This is done by inserting a substance, called a lubricant, between the moving surfaces. The study of lubrication and the design of bearings are concerned mainly with phenomena related to the oil film between the moving parts. Note that tribology may be defined as the study of the lubrication, friction, and wear of moving or stationary parts. The literature on this complex subject is voluminous. Much is collected in the CRC Handbook of Lubrication, sponsored by the American Society of Lubrication Engineers [1]. Also see [2]. The website www.machinedesign.com includes general information on bearings and lubrication.
Dry sliding wear of ductile and austempered ductile iron: effect of load and sliding speed
Published in Tribology - Materials, Surfaces & Interfaces, 2023
Shriya E, Manpreet Singh, Uma Batra, Sandan Kumar Sharma
Bearings are safety-critical components that work under severe conditions of high speed, large contact loads and high temperatures, such as in wind turbine gearboxes, automobiles or transmission gearboxes [1]. Majority of the failure of the bearing occurs due to extreme wear and lack of lubrication. Bearings along with its casings are usually manufactured by forging steels including low-carbon carburizing steel, medium-carbon steel or high-carbon bearing steels with chrome steel balls [2]. A wide variety of processes have been adopted to enhance the wear resistance of forged steels, such as nitrocarburizing, nitriding [3], carbide coatings [4], laser surface melting [2]. Usually, bearings are lubricated by employing low-friction lubricants to effectively reduce bearing friction [5]. However, poor lubricant selection, lubricant degradation, etc. can cause bearings fail catastrophically [6]. At lower loads and high speeds, bearings may also encounter skidding, leading to increased wear and reduced service life of the bearing. The use of solid lubricants like graphite is reported to reduce coefficients of friction [5]. Metal-based self-lubricating composites have also been suggested for the sliding parts because of their high strength and superior tribological properties [7].
A High Order Nonlinear Study to Evaluate the Seismic Response of Rotating Machines–Structure–Soil Foundation Systems
Published in Journal of Earthquake Engineering, 2021
Felipe Vicencio, Ernesto F. Cruz
For large rotating machines, journal fluid bearings are typically used. These elements play an important role in the seismic response and dynamic behaviour of the rotor. There are different types of bearings, which differ in their geometries and configurations; e.g. plain cylindrical, four axial grooved, elliptical, multilobe, and tilting pad. In this research, the plain cylindrical types journal bearings were considered because these are the most used on large gas/steam turbines and generators. To define the dynamic properties of the bearings, the internal forces generated in the fluid should be estimated. These properties can be expressed in terms of the hydrodynamic coefficients. These coefficients are proportional to the equivalent stiffness and damping values. Rao [1983, 2004] and Sawicki and Rao [2004] provides a good summary of how to analytically obtain these linearized coefficients for the approximation of long and short bearing type, by a perturbation from the equilibrium position of these bearings.
Experimental and theoretical investigations of heat generation in radial ball bearing
Published in International Journal of Ambient Energy, 2021
G Maheedhara Reddy, V Diwakar Reddy, T.N. Deepu Kumar
High speed machining (HSM) is a modern technology which decreases production costs but increases the productivity and quality of work piece. Even though HSM is known for long time, there is still lack of understanding its thermal characteristics. So, thermal effects on the machine tools become more significant. Bryan (1990) reported that the total thermal error arising from various sources is about 40–70%. The major heat sources during HSM process include heat generated at tool–chip interface, spindle motor and the bearings. Among these, the heat generated by machining and spindle motor is removed by coolants. But the heat generated due to rubbing contact at the bearings becomes a dominant one causing thermal expansion. Generally heat generation in bearing, where rotation takes places at low speeds, such as in bicycles and clocks, is not often studied. However, if bearings rotate rapidly such as in automotive engines, machine tools, and aircraft engines, etc., heat generation becomes more relevant. So, bearing is one of the most important elements commonly used in machinery due to its high load carrying capacity and also due to the ability to constrain the relative motion to a desired motion. Therefore, adequate knowledge on thermal parameters is required to determine the heat generation in the bearing during its running state.