The complexity of operations has increased tremendously since the days of Henry Ford and therefore requiress more thinking.
The identification of the bottleneck becomes much more difficult as we move from the high volume low variety repetitive manufacturing scenario towards low volume high variety job shops and finally to the project environment.
In a recent post I talked about how to identify a bottleneck and leverage a constraint to your advantage. However, there are several misconceptions or myths about bottlenecks that we need to debunk.
Consider a 6 step process for which the market demand is 13 pieces/hr. Process "A" can produce 17 pieces/hr, "B" 14 pieces/hr, etc.
A à B à C à D à E à F(17) (14) (13) (12) (10) (12)
Myth 1: Any resource whose capacity is less than the demand placed on it is necessarily a bottleneck.
Reality: A resource can be a non-bottleneck even if its capacity is less than the demand placed on it. In the above example consider operation "B" which can produce only14 pieces/hr, 3 pieces/hr short of the demand from "A". This is a non-bottleneck operation since it has higher capacity than the market demand.
Myth 2: The resource having highest workload is necessarily the bottleneck.
Reality: A resource can be a non-bottleneck even if its workload is highest. Process "A" has the highest workload in the sequence. It is a non-bottleneck operation since the next operation "B" has a lower capacity than "A".
Myth 3: Any resource with a queue before it is necessarily a bottleneck.
Reality: A resource can be a non-bottleneck even if an infinite queue forms before it. Process "C" will have a queue before it since process "B" has a larger production rate. However "C" is not a bottleneck since it produces at the market demand of 13 pieces/hr.
Myth 4: The resource having the biggest queue before it is necessarily the bottleneck.
Reality: A resource can be a non-bottleneck even if the queue before it is bigger than all other queues. Operation "B" will have the largest queue in front of it but again operation "B" produces at a rate more than the demand.
Myth 5: A bottleneck resource is necessarily a critical resource.
Reality: A resource can be a bottleneck even if it is non-critical. Process "D" is a bottleneck operation since it is lower than the market demand. This does not mean "D" is critical or not.
The constraint in this system is the bottleneck operation "E". Increasing the capacity at any operation other than "E" will not change the output of the system. Understanding reality will help you define a bottleneck so that it can be easily identified in your processes. Then you can use the 10 principles to manage a constraint to improve your system.
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