What is Vibration? Linear and Non-Linear Systems

from azimadli.com

Linear and Non-Linear Systems
To assist in understanding the transmission of vibration through a machine, it is instructive to investigate the concept of linearity and what is meant by linear and non-linear systems. Thus far, we have discussed linear and logarithmic amplitude and frequency scales, but the term “linear” also refers to the characteristics of a system which can have input and output signals. A “system” is any device or structure that can accept an input or stimulus

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Leading Change: Why Transformation Efforts Fail

By John P. Kotter

Over the past decade, I have watched more than 100 companies try to remake themselves into significantly better competitors.  They have included large organizations (Ford) and small ones (Landmark Communications), companies based in the United States (General Motors) and elsewhere (British Airways), corporations that were on their knees  (Eastern Airlines), and companies that were earning good money (Bristol-Myers Squibb). These efforts have gone under many banners: total quality management, reengineering, right sizing, restructuring, cultural change, and turnaround. But, in almost every case, the basic goal has been the same: to make fundamental changes in how business is conducted in order to help cope with a new, more challenging market environment.

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Disc Couplings Dump Downtime

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

Figure Out the Dollars Behind CMMS Automation

from Plant Engineering and Maintenance (PEM) magazine, April 2008.
www.pem-mag.com

When exploring automation opportunities in your facility, there are many factors to consider. These include cost versus benefit by automating, cash-flow impact, organizational readiness, ease of implementation, availability of resources, technological maturity and availability, as well as probability of success.

Most senior managers would be thrilled to discover a way to filter the never-ending stream of requests for what appears to be worthy automation projects. As one top executive said, “if we could recoup even half of all of the savings that have come forward on project business cases each year, we would have only revenue and no expenses!” Continue reading

Creating Reliable Equipment Information

by Brian Moore
Deficiencies in the integrity of equipment data and difficulties in accessing this data are costing asset-intensive companies millions of dollars a year in equipment downtime and business inefficiencies. Waste in the work management processes appears in the form of extended searches for parts and materials; wasted effort due to missing, inaccurate or out-of-date equipment data; procurement errors; and an inability to easily access data from a reliable source.The result can be expensive to these organizations. Consider the story of a feed pump that was taken out of service, repaired, and stored as a spare. A few months later, the feed pump was reinstalled and capacity dropped by nearly 25 percent.

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Matching a Hydraulic Motor to the Load

from Womack

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

Carbon Brushes for DC Motors and Generators

by Terry Taylor, Senior Consultant, IDCON INC

Brush grades are usually classified according to the manufacturing processes and the types of carbons, graphites and other ingredients used. The 4 main brush grade families are –

  • Carbon-graphitesCarbon graphite brushes
  • Electrographitics
  • Graphites
  • Metal-graphites

Carbon-Graphite Brushes made their entrance early in the brush industry.  These are generally limited to lower current densities (45 amps/sq.in.) and are used in older, slower speed motors with a maximum surface speed of 4000 ft./min. These are high friction brushes that make them very unattractive for present day use on commutators.

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Flow through Orifices

from womackmachine.com

Hydraulic Oil Flow through Orifices

The chart shows approximate pressure drops which may be expected at various flows rates through sharp edge orifices for petroleum type hydraulic oil. It may be used for designing limiting flow orifices in hydraulic systems. Chart values must be considered as approximate because a number of factors such as specific gravity, orifice efficiency, plumbing ahead of and behind the orifice may cause variations from the values shown.

By making the orifice with a knife edge, it becomes insensitive to temperature, and the flow and pressure drop will remain the same over a reasonable range of oil temperatures (and viscosity changes).

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The ‘Maintenance Crisis’ & Innovations that are Changing it

by Ashley Halligan
Property Management Analyst, Software Advice

A couple months ago, I wrote an article about the top five careers in facility management. I interviewed a broad range of professionals for that story. But it was during an interview with Joel Leonard, President of SkillTV, that I started to ponder what he referred to as “the maintenance crisis”–a depletion of skilled workers in the maintenance management workforce caused by baby boomers retiring and too few young professionals entering the field.

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How Do Variable Speed Drives Impact Mechanical Seals?

by Henri Azibert
Fluid Sealing Association

The use of variable speed drives (VSD) has become increasingly more prevalent in an effort to improve the energy efficiency of pumping systems. Efficiency is improved through the ability of the VSD to adjust the rotational speed of a rotodynamic pump and match its hydraulic characteristics to those of the system in which it operates.

Whether the mismatch was due to the variation in required pump output or incorrect sizing of the pump, there is no question that the ability to easily vary pump speed has been a major advance in the overall performance of a pumping system. This has increased the energy efficiency, as well as the reliability of the equipment. Problems—such as
cavitation or shaft deflection—can be alleviated by running the pump at optimal system speed. But how do VSDs affect mechanical seals?

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