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The operator balance chart, also known as a percent load chart, operator loading diagram, cycle time/takt time bar chart, or line balance analysis graph, provides the lean practitioner with insight into how equalized operation time is among the workers within a given process, line, or cell. The line balance rate (LBR), and the related line balance loss rate (which is simply 100% minus the LBR), quantifies how well or poorly the line is balanced.
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A lack of line balance routinely causes the waste of waiting and/or overproduction. It can also prompt overprocessing during which operators, rather than engage in the blatant waste of waiting, conduct “apparent work.” Line imbalance is an enemy of continuous flow.
Some may ask, “What the heck do I do with this?” Although there is not necessarily a magical LBR “bogey,” it’s definitely useful when developing standard work and comparing different balance scenarios.
Consider LBR a simple analytical tool. Use it when it makes sense.
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Comments
automata don't consume
Yes, that's so: workers' equalization is similar to Mendelejeff's chemical elements table. Element number 83 has such and such characteristics, and when I need it on my production line, either it is or it is not. Workers - I guess you're a worker yourself - are "a bit" more variable: equalizing them is not only a matter of charting. We are larks and we are owls: a line should start working at 5:00 a.m. and stop 2:00 a.m. next day? Thank you.
(un)Balance not the enemy...
The enemy is efficency and effectiveness of the process.
Whether the line is balanced or not, does not contribute to the assessment of the process. In your example, if the work could be adjusted for all of the operators to work 44 seconds, your math would show a perfect balance and imply a great process. Looking closer, the work you have depicted is really the loading for 3 (maybe 4) operators and 2 (or 1) of the operators are pure waste. if the line is balanced, everyone looks busy and we lose the ability to discern the waste.
A better assessment of the process would be to use the total operator time (in your example 219 seconds) divided by the total available TAKT time (5*60=300 seconds). This would represent the actual work (operator time) performed against the time the company is spending to get the results. This becomes a direct efficency number and directly correlates to "utilization" of the resources involved in the process.
To expand this concept, it's a short step to then incorporate this into an Operational Efficency and Effectiveness (OEE) number for the process. Then the OEE can be viewed and compared against all the processes to determine opportunities to improve.
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