wear and tear

wastage; depreciation; lowered condition due to frequent use

Wear and tear is a term for damage that naturally and inevitably occurs as a result of normal use or aging. It is used in a legal context for such areas as warranty contracts from manufacturers, which usually stipulate that damage due to wear and tear will not be covered.It is a form of depreciation which is assumed to occur even when an item is used competently and with care and proper maintenance. For example, friction may erode a hammer's head it is used to drive nails into wood. In the normal use of a hammer for its designed task erosion is impossible to prevent, and any attempt to eliminate this erosion would make the hammer useless. At the same time, it is expected that the normal use of a hammer will not break it beyond repair until it has gone through a certain amount of use.
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Noun
1. decrease in value of an asset due to obsolescence or use
(synonym) depreciation
(hypernym) financial loss
(hyponym) straight-line method, straight-line method of depreciation