The first one is a training example from the Universidad Tecnológica de Pereira, where they assemble Lego pieces. Here are some examples of bucket brigades. There are lots of things to take care of to make this work, and there is a risk of the result being worse than a normal balanced flow line. It may be possible to have a working bucket brigade using buffer inventories, but I believe it will be difficult. But this would be either a more complex standard (not good) or a non-standardized and hence chaotic and random action (also not good). Naturally, in the above case the first worker would not wait forever, but would maybe make himself more useful. Overall, a very inefficient system if you add inventory. The first worker slowly builds up a lot of inventory in the line.Īfter the last worker has solved his problem, the first worker would have to wait for the entire time until the last worker has completed all material. The animation below is an extreme case, where the last worker has a problem. It may be tempting to use a similar system with buffers in between, but … don’t. All other workers have to wait for the last worker to finish his process, before the workers can move forward.Īll the above examples have no buffer inventory between the processes. The image below shows a possible worst case. Where is your bottleneck? If your bottleneck is at the end of the line, all workers have to wait for the subsequent worker, and you will have lots of waiting times. This problem of waiting for the next worker depends heavily on the work speed. I repeat, the part can only be handed over if the subsequent worker gets rid of his part and is ready to walk backward. The blue worker cannot hand over the part to the gray worker until the gray worker himself gets rid of his part (by giving it to the next subsequent worker or at the end of the line). In this case the blue worker has to wait until the gray worker completes his process and moves forward.Īgain, we have waiting times. It is possible that at one point the blue worker will catch up with a subsequent worker (gray in the image). The blue worker in the image moves from station to station together with a part. Moving forward along the line should always be with a part. What work in the current process is already completed, and what still has to be done? There is a higher risk of the blue worker overlooking a step in the process, believing that the gray worker has already done that. The hand-over process now also requires additional information. Hence, a short cycle time would keep this waiting time short, whereas a longer cycle time would create quite a bit of waste by waiting.Īlternatively, especially for longer cycle times, it is also possible for the blue worker to take over the part from the gray worker while the part is still in the same process. This would obviously include waiting time. First, the blue worker could simply wait until the gray worker completes the part, and then take over the part. In reality, however, the gray worker may not yet have completed the part at his station. The succeeding blue worker would then process this part at station 4. Ideally, the preceding gray worker just completed a part at process 3 that can be handed over. The blue worker then takes over the part from the preceding gray worker. In the example picture, the blue worker walks backward until he meets the gray worker at process 3. Walking BackĪs part of the rules of a bucket brigade, a worker without a part has to walk backward until he meets the preceding worker. Let’s look first at the easier case of walking back. The hand-over process can happen when the subsequent worker walks back along the line or when the preceding worker moving forward catches up with the subsequent worker. Hence, I would like to go into more detail on how to do the hand-over of the part. An unsuitable hand-over could mean lots of waiting time for the workers. The key to making this system work is the process for handing over the part to the next worker. In my last post I explained the basics of the bucket brigade as a self-organizing manufacturing line.
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