Predictive maintenance

Predictive maintenance is condition-based maintenance that starts because a forecast shows wear. An alarm at a fixed limit is not enough: the forecast needs repeated readings, a trend, and a limit.

EN 13306 asks for a parameter that shows how the item degrades. Because the work is condition-based, it is also one kind of preventive maintenance.


In the standard	Predictive maintenance (EN 13306:2017, 7.4)
German	Voraussagende Instandhaltung in the standard; people search "vorausschauende Instandhaltung"
Also called	PdM. Gulati uses it as another name for condition-based maintenance

Is a sensor alarm predictive maintenance?

No. An alarm says a reading has reached its limit. The wear is already there, and you have no date. Predictive maintenance gives you the date: it says when the reading will reach the limit, so you can plan the job.

Sources do not agree on the word. Gulati treats "predictive" and "condition-based" as the same thing. This page follows EN 13306, which keeps them apart.

What does a forecast need?

Three things:

Repeated readings of one parameter that follows the wear.
A trend through those readings.
A limit where the part is no longer acceptable.

The trend and the limit give a date. You plan the job before that date, ideally into a stop that is already scheduled. EN 13306 names no method, so an engineer with a chart can make the forecast, and so can software. Gulati lists trend analysis, statistical process control, and preselected thresholds.

The readings must come often enough. Gulati says the check interval should be shorter than the P-F interval, the time from the first detectable sign to the failure. He adds that we have little reliable information about where the two points sit.

Where does predictive maintenance pay off?

Gulati warns that a full program with every technology is expensive. Some test equipment costs more than $40,000, and staff need training. He recommends reliability-centered maintenance (RCM) to choose where each technology pays.

Sources