Calculation of expected value MTTF and L10

1. Product life expectancy MTTF refers to the expected time when 63.2% of the product is defective, or the time when the reliability is 36.8%. Product life expectancy L10 refers to the product occurs

The expected time of 10% bad time, or 90% trust time

MTTF = t1 + L10 (t2 - t1) * 0.632 = t1 + (t2 - t1) * 0.1

T1: the minimum time for the failure rate t2: the maximum time for the failure rate

2. There is no standard definition of defects, such as:

(1) can use a batch of products for testing, after 2000,3000,5000,10000,18000 hours after testing its speed, consumption current is beyond the specification as bad

Definition.

(2) or to measure the residual amount of shaft lubricating oil with precision measuring instrument is bad definition.

3. The more samples tested, the more reliable the data, at least three.