A machine that takes 10,000 hours to build and on average produces 1,000,000 widgets before breaking down can be understood to have half its value having suffered the wear and tear of producing 500,000 widgets. 5,000 hours of that value having been transferred to the 500,000 widgets.

Mattsah you probably know this but for the benefit of others I want to indicate that this assumes that the socially necessary labor time for making a comparable machine with a lifespan of X scales linearly with X.

There is a more general formula if people are interested in that.

Suppose that the productive lifespan of a comparable machine (in years) produced using an amount of socially necessary labor x is given by the function L(x)

Then the amount of value in a machine with a lifespan t is given by: L^\1)(t) + Z where Z is the value of what is left of the machine once it is depleted, which may be useful for e.g., scrap, structural, radiological reasons. This term gets canceled out but I wanted to demonstrate that.

This means after t years of operation, the value of a machine with original lifespan T imbues into the worked products can be expressed as: ( L^\1)(T) + Z ) - ( L^\1)(T-t) + Z ) = L^\1)(T) - L^\1)(T-t)