Service life

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Service life

A product's service life is its expected lifetime, or the acceptable period of use in service. It is the time that any manufactured item can be expected to be 'serviceable' or supported by its originating manufacturer.

Expected service life consists of business policy

Product life cycle management

Product Life Cycle Management is the succession of strategies used by management as a Product goes through its product life cycle. The conditions in which a product is sold changes over time and must be managed as it moves through its succession of stages....
, using tools and calculations from maintainability and reliability analysis

Reliability engineering

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Encyclopedia

Product life cycle management

Reliability engineering

Reliability engineering is an engineering field, that deals with the study of reliability: the ability of a system or component to perform its required functions under stated conditions for a specified period of time....
. Service life is a unique commitment made by the item's manufacturer and is usually specified as a median. Actual service life is the maximal recorded life of a product.

Service life is different from a predicted life, or MTTF/MTBF (Mean Time to Failure/Mean Time Between Failures)/MFOP(Maintenance-free operating period). Predicted life is useful such that a manufacturer may estimate, by hypothetical modeling and calculation, a general rule for which it will honor warranty

Warranty

In commercial and consumer transactions, a warranty is an obligation or guarantee that an Article or Service sold is as factually stated or legally implied by the seller, and that often provides for a specific remedy such as repair or replacement in the event the article or service fails to meet the warranty....
claims, or planning for mission fulfillment. The difference between service life and predicted life is most clear when considering mission time and reliability in comparison to MTBF and service life.

For example: A missile

Missile

A guided missile is a self-propelled projectile used as a weapon. Missiles are typically propelled by rockets or jet engines. Missiles generally have one or more explosive warheads, although other weapon types may also be used....
system can have a mission time of less than one minute, a service life of 20 years, active MTBF of 20 minutes, dormant MTBF of 50 years and a reliability of .999999.

A consumer

Consumer

Consumer is a broad label that refers to any individuals or household that use Good generated within the economic system. The concept of a consumer is used in different contexts, so that the usage and significance of the term may vary....
item will have different expectations about service and longevity

Car longevity

Car longevity concerns several things: maximum service life in either miles or time , relationship of components to this lifespan, identification of factors that might afford control in extending the lifespan....
based upon factors such as use, cost, and quality.

Product strategy

Manufacturers

Product lifecycle management

Product lifecycle management is the process of managing the entire lifecycle of a product from its conception, through design and manufacture, to service and disposal....
will commit to very conservative service life, usually 2 to 5 years for most commercial and consumer products (for example computer

Computer

A computer is a machine that manipulates Data according to a list of Code .The first devices that resemble modern computers date to the mid-20th century , although the computer concept and various machines similar to computers existed earlier....
peripheral

Peripheral

A peripheral is a device attached to a host computer behind the chipset whose primary functionality is dependent upon the host, and can therefore be considered as expanding the hosts capabilities, while not forming part of the system's core computer architecture....
s and components

Electronic component

An electronic component is a basic Electronics element usually packaged in a discrete form with two or more connecting leads or metallic pads....
). However, for large and expensive 'durable' items (airliner

Airliner

An airliner is a large fixed-wing aircraft with the primary function of transporting paying passengers and carrying cargo. Such planes are owned by airlines....
, hydroelectric power plants

Hydropower

Hydropower, hydraulic power or water power is power that is derived from the force or energy of moving water, which may be harnessed for useful purposes....
) the items are not 'consumable', and service lives and maintenance activity will factor large in the service life. Again, an airliner might have a mission time of 11 hours, a predicted active MTBF of 10,000 hours with maintenance (or 15,000 hours without maintenance), a reliability of .99999 and a service life of 40 years.

The most common model for item lifetime behavior, in relative failure terms follows a bathtub curve

Failure rate

Failure rate is the frequency with which an engineered system or component failure, expressed for example in failures per hour. It is often denoted by the Greek alphabet ? and is important in reliability theory....
. On the abcissa of this curve is the term 'lambda' or failure rate, which is the inverse of MTBF. The ordinate axis is time. Initially, the bathub shows early life failures, generally not witnessed by the consumer and usually termed as factory defects. The flat middle portion of the bathtub, or 'useful life', is a slightly inclined, exponentially increasing, constant failure rate period where the consumer enjoys the benefit conferred by the item. As the bathtub reaches its far right terminus, it is exponentially increasing, modeling untoward physical effects related to Arrhenius

Svante Arrhenius

Svante August Arrhenius was a Swedish scientist, originally a physicist, but often referred to as a chemist, and one of the founders of the science of physical chemistry....
rate effects.

For an individual product, there may be several bathtub curves, related to different aspects of the product. For instance, a tire will have a service life partitioning related to the tread

Retread

A retread, or "recap," is a previously-worn tire which has gone through a remanufacturing process designed to extend its useful service life....
and the casing.

Service life examples

For maintainable items, those wear-out items that are determined by logistical analysis to be provisioned for sparing and replacement will assure a longer service life than manufactured items without such planning. A simple example is automotive tires - failure to plan for this wear out item would limit automotive service life

Car longevity

Bathtub curve

The bathtub curve is widely used in reliability engineering, although the general concept is also applicable to humans. It describes a particular form of the hazard function which comprises three parts:...
, to boot. After installation, there is a not-small probability of failure which may be related to material or workmanship or even to the process for mounting the tire which may introduce some small damage. After the initial period, the tire will perform, given no defect introducing event such as encountering a road hazard (a nail or a pothole

Pothole

A pothole is a type of disruption in the surface of a roadway where a portion of the road material has broken away, leaving a hole. Most potholes are formed due to fatigue of the pavement surface....
), for a long duration relative to its expected service life which is a function of several variables (design, material, process). After a period, the failure probability will rise; for some tires, this will occur after the tread is worn out. Then, a secondary market for tires puts a retread

Retread

A retread, or "recap," is a previously-worn tire which has gone through a remanufacturing process designed to extend its useful service life....
on the tire thereby extending the service life. It is not uncommon for an 80,000-mile tire to perform well beyond that limit.

It may be difficult to obtain reliable longevity data about many consumer

Consumer

Consumer is a broad label that refers to any individuals or household that use Good generated within the economic system. The concept of a consumer is used in different contexts, so that the usage and significance of the term may vary....
products as, in general, efforts at actuarial analysis are not taken to the same extent as found with that needed to support insurance

Insurance

Insurance, in law and economics, is a form of risk management primarily used to Hedge against the risk of a contingent loss. Insurance is defined as the equitable transfer of the risk of a loss, from one entity to another, in exchange for a premium, and can be thought of as a guaranteed small loss to prevent a large, possibly devastating los...
decisions. However, some attempts to provide this type of information have been made. An example is the collection of estimates for household components provided by the Old House Web which gathers data from the Appliance Statistical Review and various institutes involved with the homebuilding trade.

Service life

Product strategy

Service life examples

See also