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03/21/2006 08:12 AM
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During making VSM for one mixed production, I am confused how to find the real bottleneck since different product type has different C/T, consume different equipments, but follow the same line. Shall we calculate the different Takt time for different different product?If you can, Kindly Please give me some ideas.
Thanks a lot.
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03/22/2006 07:42 AM
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The way I did it was to use the takt time, not the cycle time. Keep in mind takt is a measure of time/demand, and is not related to cycle time. Takt gives you hours, minutes, or seconds per unit demanded. With a wide variety of cycle times in a mixed model cell, you can also weigh the cycle times by percentage of total demand to get an average.
In order for this to work, your cell needs to, on average, be able to meet the demand requirements. My experience in my situation (high mix, very low volume) is that the approximations are close enough to get a read on the cell's capabilities and where the waste is. Besides, the VSM is a snapshot in time and changes continually with the movement of product and the ebb and flow of demand.
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04/01/2006 08:49 AM
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Thanks for your reply. I am under the same situiation(Low volume and high mixed) like yours. My first feeling is you are right, and it is better to make some estimation of the total average. But I don't understand what is your mean to use Takt time instead of C/T. I know Takt is time/demand, C/T is for process. both are different and not conflicting. Could you take some time to explain it to me?
Now my way in which I do is to classify the rough product family and make different VSM seperately, then the problem is I have to estimate the resoure(workstation, not considering human resouces) availablity to different family.
I can't make sure too much whether I follow the right way or not.
Could you give me some suggestion or more detailed your solution?
Thank you.
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04/04/2006 05:43 AM
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Once you form the part families, identify the shared resources. If machine X is shared by two or more families, do a workload/capacity requirements analysis to see if one or more of Machine X can be dedicated to each family. If not, then do process improvements to "exploit that constraint". Shared resources will need to be scheduled carefully so that they work to suit the due dates for parts in each family. This is standard practice in the cellular manufacturing area.
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04/07/2006 09:48 AM
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On the current state VSM I always show both cycle time and takt time. This is very helpful when constructing the future state map.
Your question about the bottleneck: that is usually easy to identify because of the material or backlog in front of it. A bottleneck is also any point where the cycle time is in excess of takt time (customer demand can not be met when cycle time is more than takt).
Another way to identify the bottle neck is to look at average time (total time run divided by the number of parts produced over a period of time, usually at least a week, month is better). Average time takes break downs, stock outs, etc, into account to identify the priority station. Example: I measure ten cycles and determine that the process is well below takt time; but; when I look at the actual production over time, because of absenteeism, maintenanace, etc, the time available divided by actual parts made is greater than takt time.
This method can also be used to calculate OEE or to check OEE (because it is often, and easily, misreported).
Take care.
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06/05/2006 08:39 AM
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What you can do to define a bottelneck is to measure the valu of making 3 pieces for each operator after that you can make your line balancing again because some times you plan a production on 100% ef.
her you must think about the people ho can not reach the takt time. think about the method also because some times you have 2 lines running with the same style and one line reach the takt time and theothers no in this case you must think about the methode of working must be the same if you have something not the same
hope that you understand what I mean exactly
best regrds
said
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