Today, many flow racks are supposed to help operations. Sadly, similar-shaped racks and devices exist elsewhere, yet the “soul” differs. “Make a Buddha and don't put the soul.” Let me explain the soul using point–line–area–solid thinking.
The objective
These material presentation fixtures aim to improve Muda and fluctuations in the time needed to pick materials. Implementing these fixtures is not the objective but the method of getting there.
“Points”
First, define the material single pick point best for the worker. They are the customer, and we must respect their opinion. To avoid fluctuations, deliver one by one (or close to). The smaller the delivery, the closer we can bring the material to the desired pick point. Deliver materials as open (without packages) as possible so that we don’t have to do periodic work of opening the box.
By implementing the above, we can use the best cycle time.
Then, identify the delivery point of a material. Separate the delivery point from the pick point so the material handler will not interfere with the operator. If both points are at the same place, interference between the worker and the material handler will happen.
“Lines”
Connecting the above two points creates a line representing material flow into a workstation. The physical method of making this line is the flow rack.
Materials flowing in and something, like an empty box, going out must have a separate path. Containers should drop after the material is used, which means no or very little periodic work. This way, the operator can focus and continue its cyclic work. If these paths are the same, the next box can not wait behind the currently used box, increasing and destabilizing the periodic work.
“Areas” or the standardized work.
Once, I visited a non-Toyota plant and saw a flow rack. I was excited about many possible ways to improve the plant, so I kept observing how materials were loaded. Ultimately, the operator stopped the production, walked to the other side of the rack, and loaded the rack from the container. What is the reason for implementing this flow rack? It perfectly exemplifies “Make a Buddha and don't put the soul.”
The soul was not inserted into this flow rack because every process was designed or calculated that way. Under traditional thinking, every process kept some allowance between takt time & cycle time. There was plenty of time to keep the long periodic work. There is no need to use the flow rack as intended since everybody knows time is available on the shop floor. Nobody asked why we needed this kind of rack. Somebody should have asked, “If the worker has to stop the production and walk to the back of the rack and load, what is the difference?” Unfortunately, many focus on the tools or the shape, not the thinking. Without the correct thinking, Kaizen will be destroyed.
“Solid” or the organizational approach.
The flow racks require a material handler to deliver the parts in a special cart to each station to fulfill its objective. Even with the special cart to deliver, if the workers in the warehouse need to double handle the material onto the cart, we move Muda from one area to another. We should look for a process that touches the material. So, we went into a process with the supplier where the worker touched the part and connected the entire cycle, directly loading materials into desirable containers. When that happened, my coach said, “Finally, one Kaizen done.”
Although whether his comment was serious or a joke is now a mystery, one key lesson that I learned from this example is that traditional thinking heavily relies on mathematics. At the same time, TPS thinks based on “structure.” There are thinkings hidden behind each tool.
Ever since I read in the last chapter of Taichi Ohno’s “Workplace Management,” “Standard time should be the lowest time,” I have struggled with those who immediately say it’s impossible. But by understanding the detailed structure of the Genba, the points - lines - areas - and the body, you start to understand the vision of Taiichi Ohno.
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