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Topic Title: Building a value stream when batch works best at the beginning
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Created On: 01/31/2020 07:43 AM
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02/12/2020 09:32 AM
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Chuck Campbell

Hello all. About three years ago I started with a new manufacturing organization which makes apparel. When arriving, the entire system was your typical batch design. Throughout the past two years I've been working to slowly move them into cells based on product familys. My vision is to link the assembly cells with the sub assembly cells and ultimately cutting. My challenge that I foresee, is that cutting makes its efficiency based on layering fabric in quantities so that one cut provides more and more product per cut. As I look to reduce the batch size and cut more Skus per week I undoubtedly will be increasing the labor requirements of the cutting area. My original thought was that through the efficiency gains in the assembly area I would reduce the labor requirement and simply reallocate the labor to cutting, but in doing the math it looks as though the impact to cutting will be greater than the gains in assembly. Any suggestions or thoughts would be appreciated.
02/28/2020 12:44 PM
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Randy Estel


Not knowing the exact details concerning qty I would suggest you put together a load chart for the area which will show the amount of hours worked each workstation,the idea would be to balance the load based on the Takt time (available time divided by customer demand ,in your case desired output). It sounds like you will batch up to cutting and at some point cut the entire batch. You can only produce to your bottleneck or slowest operation.

02/28/2020 12:44 PM
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Danny Luo

What if the cutting rate keep same as before, but set a WIP cap, once the cutting parts arrive at the cap, then the cutting process is stopped and operators are transferred to sub or final assembly; once WIP arrive at lower level, then they are moved back?
02/28/2020 12:44 PM
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David Apple

Chuck - Thisis a dilemma. I assume that cutting is manual and labor intensive, and not CNC. I assume that you have looked at reducing changeover time and improving VA cutting cycle time.

So, what are the issues you are facing regarding the problems that reducing batch size are supposed to solve are?
. Reduce lead time
. Reduce inventory and the space required for larger inventory
. Additional handling,
. Damage of inventory
. If there are quality issues they will be discovered sooner with small batches and be smaller quantity of defective product
. Losing inventory so product has to be rerun
. Overproducing and having leftover material that has to be stored for long periods of time - same as lengthening lead time.

If you are not experiencing any of the above issues, then maybe larger batches are not a problem. If you are experiencing them, then there are additional costs besides labor to consider to justify smaller batches (accounting systems can mess with your improvement efforts).
Last, you may have treat cutting the same way you treat an external supplier. What are the best ways to manage an external supplier to provide best results for the rest of your operation.
02/28/2020 12:44 PM
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Kyle Meyers

From the wood furniture industry, there is a comparable problem in optimizing cuts patterns on boards. The method commonly used is to put a warehouse/supermarket between the batch and flow portions of your Value Stream. This is technically non value added, but the cost is less than the material or labor costs up stream. This also becomes your pacemaker process. Pull into it, flow out of it.
02/28/2020 12:44 PM
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Robert Simonis

I have experience in cut and sew operations. Batch and queue makes sense when measuring departments, but if you measure the total value stream or system, it is actually a problem to be solved. The larger the batch, the more productive the department is, and the less efficient the system. See the case study of Lean in a cut&sew factory here: https://a775aa33-5529-4960-966c-68c10eceeff9.filesusr.com/ugd/ece8ad_2e50cd6c74bb4907b96f4a22844c173a.pdf
02/28/2020 12:44 PM
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Mark Galloway

That sounds like a good problem. Since I don't know your situation, take anything I suggest with a grain of salt.

But with that in mind, I will offer some thoughts, so here goes.

If I was looking at this, I would stay focused on what is my problem? Is it speed through the cell? Is it the inventory levels either at FG or in-process? What? I would use data to lead me to the right path. In my past employment life, we ran into a batch material cutting process and we looked at the total cost, not just efficiency which included cutting time, setup time, quality issues, inspection time, etc. We never got to one-piece flow; however, we were able to identify the ideal number of layers of material that would maximize Safety, Quality, speed through the area, inventory, etc.

We kept telling the team that this would be many, many PDCA cycles and to focus on improving the process a little bit each cycle.

I like the fact that you are using data and thinking about it from the overall Value Stream Side. So to wrap-up, in my case, we saw many quality issues and by cutting many layers of materials, our inspection times were rather large. By reducing the number of layers we were able to reduce the quality issues and inspection time, thus increasing speed. Also in my case, if there was a quality issue, it was typically found in the assembly process which increased the cost of the defect, created massive interruption of flow, and created a variation that led to assembly defects.

I don't know if I helped any, but I can feel your pain.


03/10/2020 09:04 AM
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jason libby

i think of how the parts cut will be used by the next operation. Are they used in the same batch as they are cut? do they all go to the same place? While it might seem most efficient to cut in the batch which you are cutting it may not be necessary....How much WIP does cutting have ahead of the next process and why?