Many reliability engineers throughout history have had concerns with the reliability of the repairable system. Several researchers have presented a few calculation or estimation techniques to achieve repairable system reliability. This article explains the mean cumulative function (MCF) as a powerful and easy technique to estimate and monitor repairable system reliability. Continue reading
The SAE International standard for reliability-centered maintenance (RCM)1 says an inspection2 should be done if it is technically feasible and worth doing. The hard part is identifying when a task is technically feasible. Continue reading
End users must include bearing clearance as an integral part of designing or building a pump.
Internal clearance is one of the most important factors affecting bearing performance within pump applications. The bearing’s internal clearance is the relative movement of the outer and inner rings when they are lightly pushing in opposite directions. Movement in the diametrical direction is defined as radial clearance. Movement in the shaft’s direction is axial clearance.
How long will a bearing last? Standardized life equations help to answer.
Experience shows seemingly identical rolling bearings operated under identical conditions may not last the same amount of time. In most cases, it is impractical to test a statistically significant number of bearings, so engineers rely on standardized bearing-life calculations to select and size bearings for a particular application. These calculations continue to evolve and become more accurate over time, reflecting the collective experience of the bearing industry, including recent advances in manufacturing, tribology, materials, end-user condition monitoring, and computation. Continue reading
The most known concept to define reliability is: “Probability that an asset or system operates without failing during a given period of time under some operation conditions previously established.”
Sometimes, this concept is wrongly used due to the particular use given to the word failure. For many, failure only means shutdowns, so they construct complex mathematical formulas to calculate shutdown probability without taking into account that a failure also occurs when being inefficient, insecure and costly, having a high rejection level, or contributing to a bad image. Continue reading
by Kevin Remack
Want to expand coupling life? Who doesn’t? You may want to look into advanced-design disc couplings.
These couplings feature discs with optimized profile and thickness to provide a higher torque-to-outside-diameter ratio, higher service factors and up to 50 percent greater misalignment capability. All this provides for smaller reactionary forces on bearings compared to conventional disc couplings, which helps achieve infinite coupling life in properly specified applications. Continue reading
On the design of a new machine which is to be run with a hydraulic motor, a determination of required speed and horsepower must be made so a model with suitable ratings can be selected. This article describes several methods of making such a determination.
Hydraulic vs. Electric Motor Characteristics
Designers who are experienced only in selecting electric motor drives need to be careful in designing hydraulic drives because of important differences between these two motors.
Normally, an electric motor is selected on the basis of horsepower. It is selected to match an existing power source which provides constant voltage and frequency. If it happens to be a little oversize for the job, no harm is done, although it may cost a little too much. Continue reading
from Beta Machinery Analysis
This 2 minute, 30 second video provides an introduction to the nature of vibration, its causes, and steps to improve compressor operation, reliability, and performance. Vibration is the leading cause of maintenance headaches, on high and low speed reciprocating compressors. Primarily directed to owners, operators, packagers, and engineering companies, mechanical engineering students will also find this topic of interest. This is the first of three videos in the series from Beta Machinery Analysis.
by John M. Gross
from Plant Engineering and Maintenance (PEM) Magazine
Whether it’s turning off lights, idling back process equipment and fixing compressed air leaks to energy audits and installing compressed-air management systems-reducing utility costs can take several forms. As with any project, the return on investment should guide you on the projects that you select.
Let’s start with lighting and air leaks. While turning off lights and idling process equipment may generate a huge savings, it sends a message about conservation and preventing waste. The key is to not create any safety hazards and have a plan for start-up. Larger savings can be found with air leaks. Continue reading