Kanban Cards
What is Kanban?
The Kanban system is an information system that harmoniously controls the production of the necessary products in the necessary quantities at the necessary time in every process of a factory and also among companies.
Bullwhip effect
The Bullwhip effect in supply chain management refers to a situation where even small changes in customer demand can lead to significant fluctuations in production quantities for manufacturers.
To minimize these variations and ensure smoother production, a method called production smoothing is implemented. This process is facilitated by using Kanban cards.
Kanban cards – application
1. IT support: A support ticket can move through different stages like triage, assignment, resolution and closure. This helps keep track on number of support tickets.
2. Healthcare service: Each patient can be assigned a Kanban card and its movement can be tracked. For e.g. entry stage forms are filled, payment is done, progress in the health etc.
3. Manufacturing: To help reduce WIP (work in progress), inventory and prevent over or under production
4. Event management
Classification of Kanban cards
Production ordering Kanban
Ø These signals prompt the preceding activity to begin manufacturing when the inventory in the “semi-finished goods store” reaches a reorder level.
Ø For e.g. For an engine assembly line, Kanban’s will be attached on scheduling board which has “color-coded scale”.
Ø Inventory racks which hold semi finished goods like crank shaft, piston and cylinder are being consumed, assemblies are completed and thus inventory reduces reaching the reorder point.
Ø Kanban’s are attached on these scheduling boards signifying inventory of semi finished goods store. When Kanban’s reach the top of the red area, the respective machining shops (preceding activity) are notified to start manufacturing of the respective items.
Withdrawal kanban
Ø These signals prompt the material handler to withdraw items from the centralized store for different workstations.
Ø For e.g. There is an assembly line which produces smartphones. It has four different types of assembly lines: electronic board, screen, batteries and casing
Ø Each workstation will have its individual store where respective parts will be stocked.
Ø As the assembly progresses, parts are consumed, leading the individual stores near workstations to reach the “reorder point” levels.
Ø The Mizusumashi (kanban and material handler) will take the Kanban card of the required item as an “authorization” to withdraw the item from the central store.
Ø The central store too will have re-order points set for its inventory. Once the inventory levels reach the reorder point, the Mizusumashi (Kanban and material handler) will notify the store keeper to re order the items from the supplier.
Supplier kanban
Ø Supplier Kanban will help notify the supplier to refill the inventory levels.
Ø It is very crucial to minimize the fluctuation in ordering of inventory from the supplier. Thus two types of information are conveyed to the suppliers.
Ø There are certain calculations done by the supplier after taking into consideration monthly production schedule as follows
Supplier Kanban – Monthly Information
Supplier Kanban – Daily production schedule
Ø Depending on the withdrawal system either “later replenishment” or “sequenced withdrawal system” is used to convey the daily production schedule.
Ø Later replenishment uses supplier Kanban (now E-Kanban for supplier) to refill the inventory levels of Toyota and sequenced withdrawal system uses scheduling table conveyed by E-Kanban.
Supplier Kanban – System of later replenishment
The idea of later replenishment system is to have simultaneous activities of:
1. Loading of goods from supplier which were made on the prompt of supplier Kanban delivered one day prior. Also to submit today’s request of inventory with supplier Kanban.
2. Unloading of goods of the truck which carries the requested inventory of the prior day from the supplier on Toyota’s site.
Benefits of kanban
Ø Kanban cards help manage work in progress
Ø Reducing excess inventory of raw material
Ø Eliminating over production to a great extent
Ø Kanban board also help spot the bottle neck process/stage
Ø Kanban boards also help prioritizing the work
Ø Helps provide transparency to all the stake holders regarding current stage in any given process through Kanban board
References
1. Michel B.(Reprint 2017). Lean logistics. Productivity Press.
2. Yasuhiro M. (4th Edition). Toyota Production System. CRC Press.
3. Website: theplanningmaster.com
4. Website: talentvis.com