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Move Batching Formula
The flow time for the two station line with move batching is given by
the following equation (see Hopp and Spearman, Factory Physics®,
Chapter 9 for a derivation):
Flow Time (batching) = Flow Time (without batching) + (k-1)/2*
(t1/u1+
t2)
Where
-
k = Batch Size
-
t1 = Mean Processing Time at the
Station 1
-
t2 = Mean Processing Time at the
Station 2
-
u1 = Utilization
of the First Station
We see, that the flow time is linearly proportional to the batch size (K).
In addition, notice that the delay term grows larger as u1
gets smaller. The reason for this is that t1/u1
is
equal to the interoutput time from Station 1. For a fixed t1,decreasing
u1
is equivalent to increasing the interoutput time, which means that it will
take longer to fill up the batch and hence the wait-to-batch time will
be longer.
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