reliability engineering for maintenance

Say what you want and want what you say to your vendors. Provide explanations of the objectives in contracts in terms the vendors will understand.

Reliability audits verify your reliability program is effective and find areas of weakness for corrective action. They are inquiries by factual examination of elements of the system with a written an objective criteria for performance beginning with an assessment of how management is involved and are they effective in building an productive reliability program.

The cost of unreliability is a big picture view of system failure costs, described in annual terms, for a manufacturing plant as if the key elements were reduced to a series block diagram for simplicity. It looks at the production system and reduces the complexity to a simple series system where failure of a single item/equipment/system/processing-complex causes the loss of productive output along with the total cost incurred for the failure. If the system IS sold out, then the cost of unreliability must include all appropriate business costs such as lost gross margin plus repair costs, scrap incurred, etc. If the system is NOT sold out, and make-up time is available in the financial year, then lost gross margin for the failure cannot be counted. The cost of unreliability is a management concern connected to management's two favorite metrics: time and money.

Life cycle cost (LCC) are all costs associated with the acquisition and ownership of a system over its full life. The usual figure of merit is net present value (NPV). Projects are considered most favorable for large positive NPVs. However for many cost individual cases, decisions are made for the least negative NPVs. In all cases, the default position for accounting is to know the NPV for making no change and this is usually the last alternative for most people associated with change.

The smartest way to maintain a reliability database is in Weibull format and Weibull databases are available.

Lognormal distributions are continuous life functions that have long tails to the right (display positive skewness) in time or usage. A lognormal distribution plotted on semi-log papers would appear as a normal curve.

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

A measure of use duration applicable to an item. For example, the life units may be starts-stops, run hours, hot-cold cycles, distances traveled, emergency starts or starts, shelf life, and other measurements which motivate failures.