One of the most important Kpis to take into account in order to ensure proper maintenance management is the availability rate
But,
What is the availability rate?
An availability rate is a performance indicator used to determine how long a system or device is operational. This indicator is usually expressed to the nearest decimal point, such as "the system is operational 99.99% of the time.
It is estimated on the basis of various criteria including:
-Reliability (number of failures)
-Repair time
-Overall organisation of maintenance
There are several types of availability:
The gross availability rate:
This rate is obtained by comparing the operating time with the availability of the equipment. It is used to determine the utilisation rate of machines in order to avoid unnecessary purchases of certain equipment.
The net availability rate
This rate is determined by subtracting from the gross availability the causes of non-operation of a piece of equipment (production stoppage, strikes etc...)
The intrinsic availability rate
Intrinsic availability excludes preventive maintenance times, logistical delays and administrative delays
This rate therefore only takes into account the operating and active repair times of the equipment
It corresponds to the manufacturer's point of view. The latter has designed and manufactured the product by giving it a certain number of intrinsic characteristics, i.e. characteristics that take into account the installation, use, maintenance and environmental conditions, which are supposed to be ideal
Let's take an example to better understand how it is calculated
A machine tool manufacturer, in agreement with his customer, forecasts the intrinsic availability of a machine taking into account ideal operating and maintenance conditions: Monthly opening time = 400 hours 1 changeover per month = 6 hours Monthly corrective maintenance: failure rate = 1 breakdown/month; estimated TTR = 4 hours Monthly preventive maintenance = 3 hours
TBF=400-6-4-3 = 387 hours TTE= 6 hours Di= 387 / (387 + 7 + 6) = 0.9675
TBF: time in good working order TTR: technical repair time TTE: technical operating time
Di = Intrinsic availability
The availability rate is one of the most important KPIS to take into account: Indeed, if we do not take it into account and if we realise that our equipment is not usable at the time of an intervention, the unavailability causes consequent losses for the company
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