How to test the life of the cooling fan
the plans of the fan may be different test methods and technology, the industry usually use L10 or MTTF test, L10 by setting the fan life distribution state of some conditions, 10% of them bad, in the aftermath of the samples tested in MIL - the L10 STD - 781 on beating drums temperature acceleration method, to calculate the basis of test in 70 - usually 80 degrees.
MTTF or product undesirable average failure time, any of the following can define bad hair products, 1, fan doesn't work. 2, rotational speed is 30%. 3, 30% of the rated current is the original. Usually a batch of samples is to ensure the trustworthiness of the test.
the calculation method of life:
L10 life ( The shortest service life) ， T（ Forecast) = T ( Actual) *FC
T（ Forecast) = working temperature ( Usually 25 degrees) Estimates of L10
T ( Actual) TA temperature of actual test life
the FCC = acceleration factor
MFFT ( Mean time to failure)
A. F = E ( DH / K) * ( 1/273 + TL) - 11 ( 273 + TH)
AF = acceleration factor is fan in TH test values divided by the fan in the TL test on duty at the time of the
237 = absolute temperature, E = natural LOG, DH = activation energy
K = Bottzmann, s constant = 8. * 10-623 5, TL = = 50 degrees low temperature test, TH = high temperature test = 80 degrees.
the characteristics of life depends on the voltage, frequency, environment temperature, assembly condition, and a single use combination of air volume requirements, however, decided to life failure of key factors is the bearing and lubricating oil, bearing and is a direct relationship between fan, such as bearing outage, fans will interrupt operation, wenling chi automotive air conditioning manufacturing co. , LTD. Production of cooling fans have a variety of different bearings to choose from. With oil and oil/ball, double ball. Oil bearing life is about 10000 hours ( Under normal circumstances) , ball bearing is twice the oil-retaining bearing, at the beginning, when using oil bearing fan quieter, but long on temperature, oil bearing would quickly lose lubricating oil, can cause thermal break, the ball bearing fan will happen soon after starting more than oil bearing