The Psychology of Quality and More
In a previous article we looked at the basics of
Dual card kanban
Figure 1 shows how, at an assembly (or ‘customer process’)
point, when the parts being used (often being assembled with other parts) go
below a certain point that is defined by the
Fig. 1. Pull of parts
In Figure 2, the Assembler now can use the parts provided by the Materials Handler, who now takes the C-card to the stock point to get more parts. Note that at the stock point, there is a P-kanban card with the parts.
Fig. 2. Going to stock point
In Figure 3, the Materials Handler takes parts from the stock point to complete the requirement on the C-Kanban card. The P-Kanban card at the stock point is moved to a special rack to signal to the supplier cell that more of these parts are required.
An important point here is that the C-Kanban card has the same number of items on it as the matching P-Kanban card. If they did not match, the stock point would either run out of parts or a pile of inventory would build up. This the key aspect of the ‘dual card’ kanban.
Fig. 3. Taking parts from stock point
In Figure 4, the supplier cell takes the P-Kanban card from the stock point and uses this to trigger the manufacture or assembly of parts as defined on the kanban card. Another material handling loop may happen here, as needed. If the stock point is next to the supplier cell, then this is not necessary. This is a good reason for the stock point to be next to the supplier.
Fig. 4. Taking kanban to make new parts
Finally, Figure 5 shows how the supplier process, having completed the kanban order, puts the parts along with the matching P-Kanban card into the stock point, ready for the Materials Handler to pick it up in the next circular trip.
Fig. 5. Supplier completes Kanban order
The kanban square
The kanban container
This article first appeared in Quality World, the journal of the Chartered Quality Institute
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