Reliability refers to the equipment in the specified conditions and the specified time, the ability to complete the specified function. Specified conditions refers to the use of conditions and environmental conditions, specific conditions such as load, temperature, humidity, pressure, vibration, shock, noise, electromagnetic fields, etc., in addition to the use, operation, maintenance methods and maintenance levels and other relevant aspects. The specified time is the economic life of the system failure, that is, taking into account the conditions of obsolescence aging period and economic wear and tear period, can normally play a function of the total time. In practice, the specified time may refer to a certain period of time or number of uses, etc. The specified function refers to the expected function of the equipment system, i.e. the purpose of use that the equipment should fulfill. For different types of equipment to have corresponding specific provisions, for failure should also be given exactly.
Types
From different perspectives, equipment life can be divided into material life (natural life), economic life, technical life and depreciation life.
Folding material life
Material life, is based on the material wear and tear of the equipment to determine the service life, that is, from the equipment into use to the material wear and tear of the equipment due to aging and damage, until the scrapping of the demolition of the number of years.
Folding economic life
Economic life, is the equipment's use of the fee is within a reasonable limit of the life of the equipment. In the latter part of the material life of the equipment, the losses caused by frequent equipment failures increase dramatically. After the purchase of equipment, the more years of use, the less the annual share of the investment, the maintenance and operation of the equipment, but the more expensive. In the use of the period of the most suitable years within the lowest total cost of equipment, which is the meaning of economic life.
Folding technical life
Technical life, is due to the development of science and technology, the emergence of more technologically advanced, economically more reasonable alternative equipment, so that the existing equipment in the material life or economic life before the end of the early obsolescence. This from the equipment into use to due to technological advances and make its loss of use of the time experienced is called the technical life of the equipment.
Depreciable life
Depreciable life, is defined by the relevant state departments or enterprises to provide their own depreciation rate, the total value of the equipment after deducting the residual value of the balance of the depreciation to close to zero when the time experienced. The length of the depreciation life depends on the policies and guidelines adopted by the state or enterprise.
Folding editorial failure rate
Long-term statistics show that any equipment from the date of shipment, its failure rate is not static. The failure rate curve for a system of equipment constructed from a variety of zero parts is shown. The vertical axis of the coordinates in the figure indicates the failure rate, the horizontal axis indicates the time of experience, from the time change, the curve obviously shows 3 different zones.
Folding initial failure period
In the equipment began to use the A stage, the general failure rate is higher, but with the continuation of the equipment use time, the failure rate will be significantly reduced, this stage is called the initial failure period, also known as the break-in period. The length of this period with the equipment system design and manufacturing quality varies.
Folding occasional failure period
Equipment use into the B stage, the failure rate tends to stabilize roughly, tends to a lower fixed value, indicating that the equipment into a stable stage of use. During this period, the failure is generally random and sudden, and there is no certain pattern, so this stage is called occasional failure period.
Folding wear and tear failure period
Equipment use into the late C stage, after a long period of use, the failure rate rose again, and the failure with the universality and scale of the equipment equipment life cycle of the failure rate curve is close to the end of the service life, this stage is called wear and tear failure period. During this period, the equipment parts and components after a long period of frequent use, aging, wear and fatigue phenomenon, equipment life gradually exhausted, and therefore in a failure-prone state.
See, the failure rate characteristic curve is actually describing the equipment from the beginning of the use of the failure rate to exit the use of the law over time, that is, describing the equipment from the factory, put into use, exit the use of the whole life cycle.