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OEE PRIMER
Calculating OEE
The FormulasAs described in World Class OEE, the OEE calculation
is based on the three OEE Factors:
Availability, Performance, and Quality. Heres ho! each of these
factors is calculated.
AvailabilityAvailabilityta"es into account Down Time Loss, and
is calculated as:
Availability= Operating Time / Planned Production Time
PerormancePerformanceta"es into account !"ee# Loss, and is
calculated as:
Performance= Ideal Cycle Time / (Operating Time / Total
Pieces)
Ideal Cycle Timeis the minimum cycle time that your #rocess can
be e$#ected to achieve in
o#timal circumstances. %t is sometimes called Design Cycle Time,
Teoretical Cycle Time or!ameplate Capacity.
&ince 'un 'ate is the reci#rocal of Cycle (ime,
Performancecan also be calculated as:
Performance= (Total Pieces / Operating Time) / Ideal "un
"ate
Performanceis ca##ed at )**+, to ensure that if an error is made
in s#ecifyin the IdealCycle Timeor Ideal "un "atethe effect on OEE
!ill be limited.
$uality#ualityta"es into account $uality Loss, and is calculated
as:
Quality= $ood Pieces / Total Pieces
OEEOEE ta"es into account all three OEE Factors, and is
calculated as:
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OEE= Availability % Performance % #uality
%t is very im#ortant to reconi-e that im#rovin OEE is not the
only obective. (a"e a loo" atthe follo!in data for t!o #roduction
shifts.
OEE Factor !hit % !hit &
Availability /*.*+ /0.*+
Perormance /0.*+ /0.*+
$uality //.0+ /1.*+
OEE 20.)+ 21.1+
&u#erficially, it may a##ear that the second shift is
#erformin better than the first, since its
OEE is hiher. 3ery fe! com#anies, ho!ever, !ould !ant to trade a
0.*+ increase inAvailability for a 4.0+ decline in Quality5
(he beauty of OEE is not that it ives you one maic number6 its
that it ives you threenumbers, !hich are all useful individually as
your situation chanes from day to day. And it
hel#s you visuali-e #erformance in sim#le terms 7 a very
#ractical sim#lification.
E'am"le OEE Calculation(he table belo! contains hy#othetical
shift data, to be used for a com#lete OEE calculation,
startin !ith the calculation of the OEE Factors
ofAvailability& Performance& and#uality.
8ote that the same units of measurement 9in this case minutes
and #ieces are consistentlyused throuhout the calculations.
Item Data
!hit Length 2 hours ; )0 min. ; 4* min.
Meal (rea) ) > 4* min. ; 4* min.
Down Time
