"Wear and tear is damage that naturally and inevitably occurs as a result of normal wear or aging. It is used in a legal context for such areas as warranty contracts from manufacturers, which usually stipulate that damage from wear and tear will not be covered.
Wear and tear 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, repeated impacts may cause stress to a hammer´s head. This stress is impossible to prevent in the normal use of the tool for its designed task, and any attempt to avert it impedes its functionality. At the same time, it is expected that the normal use of a hammer will not break it beyond repair during a reasonable life cycle." - (en.wikipedia.org 13.08.2020)
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