About Portescap
Portescap offers the broadest miniature and specialty motor products in the industry , encompassing coreless brush DC , brushless DC , stepper can stack , gearheads , digital linear actuators , and disc magnet technologies .
Throughout the pre-defined timescale of the test , observations are made at regular , defined intervals from which data analysis can take place . The typical goal is zero-failures at the testing conclusion . If failures are observed before this time is reached , the required test time will be recalculated . If a low number of samples fail during testing , the failure data can be analysed with the Weibull Method , a life data analysis that determines trends of a relatively small data sample , to calculate the achieved reliability .
Testing in practice As a real-world example of RDT testing , Portescap designed a DC gearmotor for an infusion system developed by a medical device manufacturer . To validate reliability , the specification required an operational life of 10,000 hours , tested to achieve 95 % confidence . This required a B10 life calculation with RDT performed under an accelerated model .
As a gearmotor ’ s operational life is primarily dependent on the applied load and application conditions , the engineering team selected torque and speed as the stresses for accelerating the test time . The inverse power law , commonly used to test non-thermal accelerated stresses , would be used to calculate the acceleration factor .
As the specified torque requirement for the actual application was 10 mNm , for the acceleration factor calculation , the torque for the accelerated stress was set at 25 mNm , with a constant speed of 200 rpm . Then , the test duration was set using a parametric binomial method , preferred when the real lifetime of the device will exceed the allowed test duration . This generated a test time of 1,081 hours considering zero failure cases . Using Weibull calculations , a sample size of 10 gearmotors was set .
To perform the RDT , the required torque level was applied to the gearmotors , maintained using a hysteresis brake , acting as a torque limiter . Performance parameters were recorded daily , including voltage , current , speed , and temperature . On conclusion of 1,081 hours , all gearmotors completed the test without failure or abnormalities , and the required B10 life of 10,000 hours with 95 % confidence level or more was validated .
Systematic approach confirms reliability
A systematic approach to RDT achieves significant confidence in the operational lifetime of DC gearmotors . Even when actual life test duration isn ’ t a practical possibility , a robust RDT procedure creates high reliability in accelerated life testing .
Portescap ’ s engineers work alongside OEM teams to design and implement RDT whenever a project requires it . Systematic RDT doesn ’ t just assure confidence but creates actual reliability for real-world use .
For more information , visit www . portescap . com
Portescap ’ s engineers work alongside OEM teams to design and implement RDT whenever a project requires it .
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