Many factories use Kanban as a Lean tool for process control. Toyota’s Taiichi Ohno originally conceived of Kanban as a method for communicating information between suppliers (upstream processes) and customers (downstream processes). It is based on Just-in-Time production: only produce what is needed (in downstream processes), only when it is needed, and only in the amounts needed. However…most companies are still getting it wrong.
What do most companies get wrong?
The Kanban card is actually a production order with information such as article description, parts number, lot size, supplier info, delivery location… The problem is that often the most important information is missing – the product / part replenishment Lead Time. This is an important detail and represents a promise between the (internal) supplier and (internal) customer. If this “agreement” is not clearly described and cannot be complied with, it can cause missing parts and even production stoppages.
How to get it right
Certain conditions are necessary when using Kanban to ensure that parts are available in the set replenishment time.
Between internal "supplier" and "customer" (= preceding and following processes)
- steady volume of material consumption
- guaranteed capacity for the agreed Kanban quantity
- items have short transportation cycles
- linear manufacturing processes, no process loops
- production with small lot sizes = short delivery times
- 100% reliable material availability
Across the entire factory
- High levels of standardization in processes and work methods
- Accurate process cycle times
- All employees adhere to established standards / rules
Kanban in practice
Best practice Kanban can only be effective when the above requirements are met and maintained. However, in some manufacturing situations, such as machine tool production, it is often difficult to manage the delivery of parts between processes with just Kanban.
If you are in an industry with fluctuating levels of (parts) demand, the introduction of an APS (Advanced Planning and Scheduling) system is perhaps the better choice for you and will give you such benefits as:
- For all parts: precisely timed sequence planning, which enables accurate MRP calculations.
- For made-to-stock parts: automatic planning for warehouse replenishment orders according to defined target inventory levels.
Keiji Fujii, Managing Partner of Asprova AG