All calculations in IFS/Overall Equipment Effectiveness (IFS/OEE) are performed over a given time interval. Events that have at least a part of its duration within this time interval will be included in the calculation—or rather, only the part of the event which is included in the time interval will be included in the actual calculation. For such an event an average is calculated and this average is then multiplied with the part of the event that is within the searched time interval.
There are six different system stop event types in IFS/OEE. Five of these system stop event types have an impact on APQ and TEEP calculations. The sixth system stop event is No Production Loss (NL) and is not included in this help file. All used stop event types are defined in Setup OEE/Define Event Types.
Events with system event type Production Halted are considered as excluded stop event time during APQ calculations. However, these Production Halted events are included in TEEP calculations. Excluded stop event time is normally planned time, not scheduled for production (e.g., scheduled preventive maintenance, redundant production unit, experiment time, planned training, holidays etc.). A stop of this kind is showed in black in the production rate charts.
In the OEE system, both external and internal stop time for Production Halted stop events are always included in all types of internal and external calculations.
Events connected to the system event type Planned Stop are shorter stops planned in advance that are not really considered as preventative maintenance, but rather as a part of a more regular maintenance and therefore should be considered when calculating APQ. A stop of this kind is shown in red in production rate charts.
In the OEE system, both external and internal stop time for Planned Stop events are always included in all types of internal and external calculations.
Events connected to the system event type Line Failure are stops that could be said to be caused by technical reasons. This could be any equipment failures regardless if this is due to maintenance errors [or not]. It could also be a stop caused by dirt or scratches on equipment. A stop of this kind is shown in red in production rate charts.
Events connected to the system event type Unplanned Stop are stops that could be said to be caused by operational reasons. This could be procedures not followed properly or operator errors. A stop of this kind is shown in red in production rate charts.
Events connected to the system event type Short Stop are in conjunction with, for instance, start-up procedure. Note that Short Stops only have an influence when calculating the P figure.
Each stop event has to be connected to a loss cause. This loss cause is then connected to a loss cause group and each loss cause group can finally be defined as either external or internal.
External loss cause groups should be used to group loss causes that represent events that have happened outside the production unit and that the operating personnel had no possibility to avoid or act upon. This could, for instance, be things like stop on previous production units in a production line, lack of some kind of incoming material, power failure or lack of orders. When calculating the APQ figure or the TEEP figure, you can either choose to include or exclude external events in the calculation.
OEE provides a complete picture of a machine’s health – not just how fast it can make parts but how much the potential output was limited due to lost availability or poor quality. The OEE figure shows how effectively the process runs when it is scheduled to run and is expressed as a number between 0% and 100%. The OEE figure is calculated according to the following formula:
There are different levels of APQ and how it is calculated:
The TEEP figure is calculated in the same way as APQ but in this calculation we do not exclude any stop time. In IFS/OEE this means that stop events connected to the system stop event type Production Halted are included in the calculations in the same way as any other stop event connected to system stop event type Short Stop, Planned Stop, Line Failure or Unplanned Stop. E.g. if the calculation also include external stop events, TEEP show how high efficiency the production unit have had in total regardless of why the production unit occasionally did not produced any goods.
The APQ breakdown included in IFS/OEE includes all APQ values and you can also view if there are any excluded time or not, e.g. if APQ have the same value as TEEP [or not]. APQ breakdown is calculated excluding external events and against the goal production rate.
We define availability as a comparison of the planned
operating time and the time in which the machine is actually making products.
The availability is expressed as a number between 0% and 100%.
The availability is calculated according to the following formula:
Planned operating time is calculated as Total Operating Time
(TOP) minus any excluded stop event time. TOP is the total time the production
unit could be used for production. If the nominal runtime (defined in
Setup OEE/Define Production Units) is set to 24 hours per day, and analyzing
is performed over a week, then TOP is 24 * 7 = 168 hours. Seven days a week is
assumed as working days.
Excluded stop event time is normally planned time not scheduled for production.
In IFS/OEE all such excluded time should be registered on a stop event
connected to the system stop event type Production
Halted.
This value is calculated as the sum of the length of all the
planned stops from the stop event registrations. Observe that in IFS/OEE a
planned stop for preventive maintenance and a planned stop for normal
maintenance work can differ. In IFS/OEE all such planned time should be
registered on a stop event connected to the system stop event
type Planned Stop.
In the OEE system, both external and internal stop time for Planned Stop events
are always included in all types of internal and external calculations.
This figure is calculated as the sum of the length of all unplanned stops from
the stop event registrations. In IFS/OEE all such planned time should be
registered on a stop event connected to the system stop event types
Unplanned Stop or Line
Failure. OT
– Operating Time All POT minus all downtimes (both
Planned Stop Time and Unplanned Stop Time). Performance is a comparison between the actual productions
rates during the available time compared to what could have been produced under
ideal circumstances. In IFS/OEE you can choose if the comparison should be made
against a theoretical maximum production rate or a set goal production rate. No
production rate can be higher than the theoretical maximum production rate but
individual events can be registered with a higher production rate than the goal
production rate value. All production rates are set per production unit and
product/quality combination (defined in Setup
OEE/Define Goals/Production
Rate Goals). The performance is expressed as a number between 0% and
100% as long as the comparison is made against the theoretical max production
rate. If the comparison is made against the goal production rate the value could
be larger than 100%. The availability is calculated according to the following
formula:
TP - Total Produced
This is the total amount produced during the period, expressed in
the unit of measure of the production unit (defined in
Setup OEE/Define
Production Units). This value is calculated as the sum of all production
registrations during the interval.
POT - Planned Operating Time Planned operating time is calculated as Total Operating
Time (TOP) minus any excluded stop event time. TOP is the total time the
production unit could be used for production. If the nominal runtime (defined in
Setup OEE/Define Production Units) is set to 24 hours per day, and
analysis is performed over a week, then TOP is 24 * 7 = 168 hours. Seven days a
week is assumed as working days.
Excluded stop event time is normally planned time not scheduled for production.
In IFS/OEE all such excluded time should be registered on a stop event
connected to the system stop event type Production
Halted.
A - Availability
This is the availability of the production unit that
was calculated previously.
MPS - Maximum Production Speed. Since this can be different for different qualities, it is
calculated for every combination of production unit, product and quality
(defined in Setup OEE/Define Goals/Production Rate Goals). Then
the maximum speed is considered relatively to its part of the production during
the selected period. This is regardless of whether the calculations are made
against the theoretical max production rate or if it is done against the goal
production rate. Quality is expressed as a comparison
of the number of products made and the number of products made that meets the
customer specification. In short, it determines the percentage of the total
output that is good (i.e. all products including production, engineering, rework
and scrap). The quality is expressed as a number between 0% and 100%.
The quality is calculated according to the following formula:
TP - Total Produced This is the total amount produced
during the period, expressed in the unit of measure of the production unit (defined
in Setup OEE/Define Production Units).
This value is calculated as the sum of all production registrations during the
interval.
SQ – Scrapped Quantity This is the scrapped quantity
connected to a production event that was produced during the period. This value
is calculated as the sum of all scrapping event registrations. Goal Production Rate (GPR) = 15 ton/h Total Produced (TP) 615 ton (GPR * Full production during
available time, i.e. PT + NL = 15 * (18 + 12 + 11) = 615) A = Availability = (POT – PST – UST) / POT = OT / POT P = Performance = TP / (POT * A * MPR) Q = In this case there are no scrappings so Q is always
100% All calculations are done against GPR. No scrappings are
made during this time interval. There are three levels of APQ: When calculating TEEP we consider all stop time,
regardless of the stop type and if it is external or internal. PH is seen as PST time
when calculating TEEP. This means that TEEP can be seen as the “absolute truth
value” when it comes to viewing how well a production unit performs. On the
other hand this value includes quite a lot of stop time that perhaps neither the
System Engineer nor the Operator roles have any
control or influence over. A-TEEP = OT/POT = (POT – PST – UST) / POT = (96 – (1 + 2 +
3 + 4) – (7 + 8 + 9 + 10)) / 96 = 52 / 96 = 54,2% P-TEEP = TP / (POT * A * MPR) = 615 / (96 * 0,542 * 15) =
78,8% TEEP = A-TEEP * P-TEEP * Q-TEEP = 0,542 * 0,788 * 1 =
42,7% When calculating APQ in IFS/OEE we never consider any PH
time. The reason for this is that such time is seen as time that is not included
in POT, and the POT is therefore in IFS/OEE calculated as: POT = AT - PH In IFS/OEE include external stop means that all stop times
are included when calculating A, regardless of whether it is internal or
external. Since APQ does not consider PH this value could be seen as
lesser than “absolute truth” but on the other hand this is a value that both the
System Engineer and the Operator roles can relate to a bit more. A = OT/POT = (POT – PST – UST) / POT = ((AT – PH) – PST –
UST) / (AT – PH) = ((96 – (1 +2)) – (3 + 4) – (7 + 8 + 9 + 10))) / (96 – (1
+ 2)) = 52 / 93 = 55,9% P = TP / (POT * A * MPR) = TP / ((AT – PH) * A * MPR) =
615 / ((96 - (1 + 2)) * (0,559) * 15) = 78,8% APQ = A * P * Q = 0,559 * 0,788 * 1 = 44,1% When calculating APQ in IFS/OEE we never consider any PH
time. The reason for this is that such time is seen as time that is not included
in POT, and the POT in IFS/OEE is therefore calculated as: POT = AT - PH In IFS/OEE exclude external stop means that all external
stop times are seen as time that “did not happen”. External time is regarded in
the same way as if it had been reported as PH time when no production was
planned. Therefore APQ-int is calculated as: POT = AT - PH - EXTERNAL Since APQ-int neither considers PH or external events,
this value could also be seen as lesser than “absolute truth” but on the other
hand this is the proper value that both the System Engineer and the
Operator roles could mostly relate to.
A-int = OT/POT = (POT – PST – UST) / POT = ((AT – PH - EXTERNAL) – PST – UST) /
(AT – PH - EXTERNAL) = ((96 – (1 +2) – (7 + 9)) – (3 + 4) – (8 + 10)) / ((96 –
(1 + 2) – (7 + 9)) = 52 / 77 = 67,5%
P-int = TP / (POT * A * MPR) = TP / ((AT – PH - EXTERNAL) * A * MPR) = 615 /
((96 – (1 +2) – (7 + 9)) * (0,675) * 15) = 78,8%
APQ-int = A-int * P-int * Q-int = 0,675 * 0,788 * 1 = 53,2% The following table displays a summary of the results from the above
calculations: This means that Performance is always
remains the same in terms of TEEP, APQ or APQ-int. MTBF shows the average time in hours between the stop
events that caused production to stop. In IFS/OEE this will be all stop events
connected to system stop event types Planned Stop, Line Failure and Unplanned
Stop. MTBF is calculated according to the following formula:
POT - Planned Operating Time Planned operating time is calculated as Total Operating
Time (TOP) minus any excluded stop event time. TOP
is the total time the production unit could be used for production. If
the nominal runtime (defined in Setup OEE/Define Production Units)
is set to 24 hours per day, and analyzing is performed over a week, then TOP is
24 * 7 = 168 hours. Seven days a week is assumed as working days. Excluded stop event time is normally planned time not
scheduled for production (e.g., scheduled preventive maintenance, redundant
production unit, holidays etc.). In IFS/OEE all such excluded time should be
registered on a stop event connected to the system stop event type Production
Halted (defined in Setup OEE/Define Event Types). A stop of this
kind is shown in black in production rate charts.
IST
- Internal Stop Time
This figure is
calculated as the sum of all internal stop event durations,
except for all events of the stop event types PH (Production Halted) and NL (No
Production Loss).
It is the cause
group connected to the cause entered on the stop event that decides if a stop
event is internal or external.
NE - Number of
Errors
Number of stop
events during the search criteria period with the same condition as for IST. MTTR + MWT
shows the average time for setting the facility into production again after a
production stop. This is an indicator of how well the maintenance organization
is performing.
IST - Internal
Stop Time This figure is
calculated as the sum of all internal stop event durations,
except for all events of the stop event types PH (Production Halted) and NL (No
Production Loss).
It is the cause
group connected to the cause entered on the stop event that decides if a stop
event is internal or external.
NE - Number of
Errors Number of stop
events during the search criteria period with the same condition as for IST.
Performance (P)
Quality (Q)
APQ Calculation Example
Calculations
TEEP
APQ (inclusive external events)
APQ-int (external events excluded)
Summary
Figure
TEEP
APQ
APQ-int
Availability
54,2%
55,9%
67,5%
Performance
78,8%
78,8%
78,8%
Total
42,7%
44,1%
53,2%
Maintenance Related Key Figures
Mean Time Between Failure (MTBF)
Mean Time To Repair + Mean Waiting Time (MTTR + MWT)
