reliability engineering for maintenance

Overall equipment effectiveness (OEE) is a manufacturing index to reduce complexity of discrete systems for problem solving and benchmarking.

Reliability-Centered maintenance (RCM) is a systematic planning process used to determine the maintenance requirements for a system. RCM expects the system has an inherent reliability and maintenance requirements are imposed upon the baseline of inherent safety and inherent reliability which can be no better than the worst than designed into the system.

Reliability is the probability that a device, system, or process will perform its prescribed duty without failure for a given time when operated correctly in a specified environment.

The International Electrical Congress (IEC) defines dependability as "Dependability describes the availability performance and its influencing factors: reliability performance, maintainability performance and maintenance support performance." MIL-HDBK-338 defines dependability differently as a measure of the degree to which an item is operable and capable of performing its required function at any (random) time during a specified mission profile, given that the item is available at mission start. (Item state during a mission includes the combined effects of the mission-related system R&M parameters but excludes non-mission time; see availability.) Dependability is related to reliability with the intention that dependability would be a more general concept than the measurable issues of reliability, maintainability, and maintenance.

Failure forecasting is a projection of failures into the future based on assumed or documented failure details

Reliability block diagram (RBD) models are graphical representations of a calculation methodology for reliability systems.

A tool for measuring the % of time an item or system is in a state of readiness where it is operable and can be committed to use when call upon.

A measure of how well the product performance meets objectives. In short how well are the outputs actually accomplished against a standard? Capability is frequently the product of efficiency * utilization.

Reliability block diagram (RBD) models are graphical representations of a calculation methodology for reliability systems.

The concept is derived from the human life experience involving infant mortality, chance failures, plus a wear out period of life since data for births and deaths is accumulated by government agencies. Most equipment lacks the birth/death recording by government agencies and most non-human systems can be regenerated to live/die many times before relegation to the scrap heap.

A test method of increasing loads to quickly produce age-to-failure data with only a few data points which are then scaled to reflect normal loads.

Publisher's note: When a person has a hammer - everything looks like a nail. Once a maintenance engineer learns techniques like Reliability Centered Maintenance (RCM) or Weibull analysis, it seems like they apply the technique to every potential area of failure they can find - whether RCM or Weibull analysis can add value or not. Reliability tools must be used in the proper context to create the best result and the more tools we understand the better we can apply them.

We asked our favorite reliability guru, Mr. H. Paul Barringer to help us understand what reliability tools are available to us as maintenance professionals, when we can and should use them and what results we can expect if we apply them correctly.   - Terrence O'Hanlon, CMRP, Publisher