Looking for an adjective that describes a tool part that is subject to wear and tear, and is requires replacement over time

Solution 1:

Consumable is the usual word. It differs from perishable and disposible because perishable items (like fresh fruit) deteriorate whether they are used or not and disposable items (like examination gloves and cleaning cloths) are discarded after use because they are contaminated rather than because they are worn out.

Consumable items, however, wear out (ie are consumed) by use and last longer the less they are used. A hacksaw blade might wear out in a few minutes if it's used a lot or it might last for years if it's kept in a shed and used occasionally. Similarly a ream of printer paper will last a long time if used rarely.

This does not prevent items being all of consumable, perishable and disposible under the right circumstances but consumable is the word that would fit your requirement. It is the word which is used for anything which wears out with use and cannot be repaired, the fact that it is also used for items which are actually consumed (like food and fuel) does not make it the wrong word for items which wear out.

Other languages may have a slightly more specific word but I don't believe that English does. This is common when comparing different languages, think of the French 'combien' and the German 'wieviel' which are pretty much exact translations of each other but both translate to either 'how much' or 'how many' in English depending on whether the subject of the question is a count or non-count noun.