Mst - Life Data Analysis

VEM

Life Data Analysis of Mechanical Soak timers

Reliability Engineering

VEM Life Data for MST samples of 7-Jul-05, 15-Jul-05, 9-Aug-05

Sl. No

St. date

End. date

Total Cycles Sample size Failures

Remarks

1

7. Jul. 2005 9. Aug. 2006

6466

5

5

4 Stops (1,4,627,4722), 1 total time more

2

15. Jul. 2005 6. Aug. 2006

6417

5

3

2 Stops (622, 4328) , 1 total time more

3

9. Aug. 2005 14. Sep. 2006

6229

10

3

2 Stops (2790, 3896) , 1 No Buzzer (543)

Reliability Engineering

VEM R(t) : This shows the value of the probability that the product reaches 't' duration of life Example : R(5500) is the probability that the product meet 5500 cycles

Left Censored : When the failures have occurred before particular cycles / time. Example, If it is observed that the total time of the timer is more at the end of the life test then we say it as left Censored. (Failure occurred before say, 6466 cycles) Right Censored : When the failures have occurred after particular cycles / time. Example, If it is observed that there is a product which did not fail at the end of the life test then we say it as right Censored. (Failure may occur after say, 6466 cycles)

Reliability Engineering

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Reliability Engineering

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Reliability Engineering

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Reliability Engineering

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Result of the Weibull Analysis on MST of 07-Jul-05, 15-Jul-05, 09-Aug-05 Sl. No

MST Date

R(5500)

R(2100)

Shape value

Scale value

Best Fit

01

07-Jul-2005

0.0168

0.3477

0.3341

298

Weibull / Normal

02

15-Jul-2005

0.4656

0.7938

0.9044

7000

Normal / Weibull

03

09-Aug-2005

0.7304

0.9007

0.8935

19348

Weibull / Normal

R(5500) is the probability that the timers from that batch will reach the expected life 5500 cycles i.e., 10 years. R(2100) is the probability that the timers from that batch will reach the expected life 2100 cycles i.e., 3 years. Best Fit is the distribution that best fits the data of the Test Results. And that distribution is used for the Reliability Analysis.

Reliability Engineering

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Decrease in value shows improvement over time

Increase in value shows improvement over time

Reliability Engineering

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Reliability Engineering