7. Comment on
the Solution of the Example and Input-output
Comment on the Input-output Control:
The numbers in the "cumulative deviation" and "cumulative deviation" rows are
computed by subtracting the planned amount for a week and adding the result to the
cumulative deviation for prior week.
The actual backlog numbers refer to the backlog at the end of a week and are
computed by starting with the prior weeks' actual backlog and then adding the actual
input during the week and subtracting the actual output during the week.
Input-output control might be maintained to monitor tha gateway or starting work
centres, because the output of these centres determines the input to subsequent centres and the entire factory. If the capacity of some downstream work centre(a bottleneck) is less
than that of the gateway work centre, the input at the gateway can be geared to the output
at the bottleneck to prevent excessive WIP. Capacity at any work centre should be
adjusted, if practicable, to keep queues from becoming large, because coordinated plans
can be wreaked by unplanned delays at any work centre through whcihc one part of an
assembly passes. Effective input-output control should keep the average actual lead time
equal to the lead time offsets used when the schedules were made.