Cycles or Time

Speaking Of Reliability: Friends Discussing Reliability Engineering Topics | Warranty | Plant Maintenance

Cycles or Time

Abstract

Kirk and Fred discuss whether we should use time or number of cycles or total time a product has been available for use.

Key Points

Join Kirk and Fred as they discuss a question from a listener on whether it’s better to use time or cycles as a reliability metric.

Topics include:

• As with most of our discussions, the decision to use cycles or total time depends on the type of system you are measuring. In pumps, valves, and other mechanical systems, the time between use can significantly affect wear and fatigue damage as seals and bearings lubrication may evaporate or its viscosity changes with temperature.
• Using an electro-mechanical system continuously and not having many on-off cycles results in different mechanical wear effects versus using the system once daily.
• Starting a warm car engine is much less stressful and damaging than starting an engine after it has cooled down. The same is valid with electronics assemblies, especially in power electronics.
• Many products can log the cycles and total power on time, which differentiates between cycling and frequency of processes or on-off cycles.

Enjoy an episode of Speaking of Reliability. Where you can join friends as they discuss reliability topics. Join us as we discuss topics ranging from design for reliability techniques to field data analysis approaches.

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Show Notes

You can now purchase the most recent recording of Kirk Gray’s Hobbs Engineering 8 (two 4 hour sessions) hour Webinar “Rapid and Robust Reliability Development 2022 HALT & HASS Methodologies Online Seminar” from this link.

Please click on this link to access a relatively new analysis of traditional reliability prediction methods article from the US ARMY and CALCE titled “Reliability Prediction – Continued Reliance on a Misleading Approach”

For more information on the newest discovery testing methodology here is a link to the book “Next Generation HALT and HASS: Robust design of Electronics and Systems” written by Kirk Gray and John Paschkewitz.

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