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MTBF (Mean Time Between Failures) is the numerical value that determines the number of repair parts prepared for products that are operating in the market.
(example) If there are 1,000 products operating in the market; the number of units that will fail after 100 hours is estimated and the number of products that must be prepared is determined.
The calculation formula used in this case is “1,000 units × 100 hours = 100,000 hours/units”.
The forecasted number of failures is 100,000 ÷ 50,000 = 2 units if the MTBF is 50,000 hours.
Therefore, there should be replacements ready for 2 units if 1,000 of these devices are used for 100 hours.
MTBF calculation values vary according to manufacturer as their calculation methods and calculation conditions are different.
There are two kinds of calculation methods and various environmental conditions depending on how they are combined.
Basic failure rates for parts are figures produced by the American Military Standard MIL STD 217, the JEITA, and so on. This is why there are multiple forms of calculation results.
Calculations are based on parts stress reliability projections and parts count reliability projections.
The generic failure rates for parts are classified by usage environments, and with our part count reliability projections;
Ground, benign: An environment fixed on the ground where people can live
Ground, fixed: An environment fixed on the ground for devices
are assumed for calculations. “Ground, benign