What does a numerical rating mean? Mechanical equipment or device

[symbolipoint]

TL;DR Summary

What exactly does "Rating" mean for a piece of equipment or mechanical device?

A certain mechanical appliance or device is given a rating that says, a certain operation or a certain movement can be performed some specified thousand times. What does the rating really mean? Was that movement or operation performed until the piece failed? Does it mean some advanced test was made in an abbreviated or accelerated fashion, and an estimate or prediction was made to give the number of times as a rating? Should the person receiving the information on a rating include some range up or down from the rating?

 

[Lnewqban]

Could you provide us with an example of machine and rating?

Tested or calculated cycles based on material fatigue is the closest I know about that.
The automotive industry also do a lot of accelerated tests on some mechanisms to verify longevity and warranties (suspensions, door locks and hinges, etc.).

Please, see:
https://en.m.wikipedia.org/wiki/Accelerated_life_testing

https://en.m.wikipedia.org/wiki/Service_life

 

[Averagesupernova]

TL;DR Summary: What exactly does "Rating" mean for a piece of equipment or mechanical device?

Was that movement or operation performed until the piece failed?

I've actually watched equipment do this. Not necessarily to complete failure but X cycles until a certain amount of wear or damage has occurred. This particular case was a cable assembly used in lab-type test equipment. Sorry I can't tell you the number of cycles.

 

[anorlunda]

I look at the nameplate rating as primarily a legal thing. It is the standard of performance that the nameplate warrants. Exceeding the nameplate rating voids all guarantees and warranties of performance.

How the manufacturer set the numbers on the nameplate can not be determined in the general case. They may or may not be tied to factual evidence.

 

[symbolipoint]

Something about the meaning, as indicated in one of the links says, "life expectancy" or "expected number of uses". That is likely as good as I will find. Just a prediction based on some testing or based on some kind of model.

Still very very general, if a spring has a rating of 1600 cycles, this is a prediction that it can be stretched & released OR squished & released 1600 times to still work at its best.

That seems to be just what "rating" means.

 

[Baluncore]

https://en.wikipedia.org/wiki/Reliability_engineering#The_importance_of_language
https://en.wikipedia.org/wiki/Mean_time_between_failures
https://en.wikipedia.org/wiki/Bathtub_curve