1-Long pull system(Previous)
In
the long pull system, the triggering mechanism works in the same way as
in a pull system. However, the control of the long pull encompasses
more than one workstation. In this system one unit is allowed to enter
the system at the same time that one unit is pulled at the end of the
pull. The individual buffers are not limited, but the total number of
units in the span of the long pull is limited.
(System Approach to Computer-Integrated Design and Manufacturing, Nanua Singh, p.460)
Lambrecht and Segaert introduced the concept of the long pull system. In this system one unit is allowed to enter the system, the instant that one unit is finished at the end of the pull. The individual buffers are not limited, but the total number of units i the span of the long pull is limited. This system triggered in the same way that a pull system triggers production from the preceding process. However, the control of the long pull encompasses more than just one workstation. In a figure 28.11 the span of the pull originates in process 3 and creates a pull o process 1 when the trigger level at process 3 is activated. Once process 1 is started the unit produced is pushed through the subsequent processes (2 and 3) in a smillar manner as that of push system. A trigger may be active, but process 1 may not produce an additional part if the maximum inventory allowed within the span of the pull is reached. In this study the authors compared the long pull strategy with otler allocation strategies and concluded that it performs them. Brar and Singh have provided a detailed analysis on the lng pull systems, including how to find the location of the long pull, the span of control of each long pull, and the correspondig amount of WIP(Work in Process) inventory to be allocated. They also confirmed the results of the previous study.
(Dorf, R. C., Andrew Kusiak, A. , Handbook of Design, Manufacturing and Automation, p.582)
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