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Professional Scrum with Kanban came out in February 2018, and it can be found here. The Lean Kanban method is described in the Essential Kanban Condensed Guide, here. The original Toyota Kanban has been around for a little longer, not to be confused with Kaizen as per https://www.youtube.com/watch?v=wot9DFzFRLU or https://www.youtube.com/watch?v=E6rRHqb5MV0.
This video at https://www.youtube.com/watch?v=5izyN66PTxs in two minutes the original Kanban and Kanban for knowledge work.
I was first introduced to the original Toyota Kanban at a factory in Ireland for a key partner for a global computer company. I remember people picking components from pairs of bins, focusing on one bin of each pair at a time. Kanban aligns inventory levels with actual consumption. When a bin would empty, a flag would raise signalling “please replenish me” to the chap from the warehouse watching for such signals from the end of the assembly line.
After all, he could not put the entire warehouse on the line. This was just in time replenishment, as the other bin of the pair was not being consumed while the operator proceeded with her picking work. The size of the bin was relative to the components in the bin, as the warehouse chap needed enough time from the signal to get parts from the warehouse to replenish the now empty bin of the pair before the other bin emptied also.
Allowances to be made for variation, how long the warehouse chap will take to see the signal, respond to the signal, complete replenishment, multi-tasking of the warehouse chap, production pace, and the supply chain for those components to even get them into the warehouse based on a supply-chain system. All sorts of charts were used to figure out the sweet spot, as there were many pairs of bins, one pair per component as I recall.
Indeed I also saw a CONWIP system, with constant replenishment of 1 large component per pull signal, this could help in the event of a fit of purpose replenishment time (to avoid unfit for purpose waiting — I mean this is the literal sense, I am not referring to David Anderson’s book on that topic — good book by the way).
Given that information on Toyota Kanban is in a number of places, I’ll try to pull it together here in summary….
I took some of this text straight (in italics) out of Wikipedia….
Toyota has formulated six rules for the application of kanban:
- Each process issues requests (kanban) to its suppliers as it consumes its supplies.
- Each process produces according to the quantity and sequence of incoming requests.
- No items are made or transported without a request.
- The request associated with an item is always attached to it.
- Processes must not send out defective items, to ensure that finished products will be defect-free.
- Limiting the number of pending requests makes the process more sensitive and reveals inefficiencies.
We also know from the Theory of Constraints that excess inventory is typically a sign of a badly designed system. Throughput accounting rather than Cost accounting is recommended to avoid “silly games”. I saw a speech this year from a kind of famous guy who won a Finance Wizard of the year award and showed his prison card from the same year:). I think he took to to the extreme, I jest of course:). See https://www.youtube.com/watch?v=t_x3F3v6xBY&t=54s .
Kanban cards are a key component of kanban and they signal the need to move materials within a production facility or to move materials from an outside supplier into the production facility. The kanban card is, in effect, a message that signals the depletion of product, parts, or inventory (this is the key difference to the kanbans for knowledge work of knowledge workers , where each card represents a valuable knowledge work item). When received, the kanban triggers replenishment of that product, part, or inventory….
An example of a simple kanban system implementation is a “three-bin system” for the supplied parts, where there is no in-house manufacturing. One bin is on the factory floor (the initial demand point), one bin is in the factory store (the inventory control point), and one bin is at the supplier. The bins usually have a removable card containing the product details and other relevant information — the classic kanban card.
When the bin on the factory floor is empty (because the parts in it were used up in a manufacturing process), the empty bin and its kanban card are returned to the factory store (the inventory control point). The factory store replaces the empty bin on the factory floor with the full bin from the factory store, which also contains a kanban card. The factory store sends the empty bin with its kanban card to the supplier. The supplier’s full product bin, with its kanban card, is delivered to the factory store; the supplier keeps the empty bin. This is the final step in the process. Thus, the process never runs out of product — and could be described as a closed loop, in that it provides the exact amount required, with only one spare bin so there is never oversupply. This ‘spare’ bin allows for uncertainties in supply, use, and transport in the inventory system. A good kanban system calculates just enough kanban cards for each product. Most factories that use kanban use the coloured board system (heijunka box).
Courtesy of Wikipedia under a CC license
For a two-bin scenario like the one described above, Kanban calculation variables for a signal kanban system include monthly demand (MD), changeovers per month(CO/M), average daily demand (AD), replenishment lead time (RT), safety factor (SF), and container quantity (CQ).
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