Lean is a powerful business improvement activity that works so well because it is simple and can be easily understood by the entire organization. Kanbans, a lean information and material flow control tool, are a great example of this simplicity. However, this simplicity seems to confound many organizations.
Of all the lean tools, kanbans are most likely to have implementation difficulties. By this, I mean implementations that are using far less than a kanban’s full process improvement potential, or implementations that are started and then abandoned.
In this article, I will present considerations, guidelines and rules when implementing kanbans.
Considerations
Kanbans are:
- Communication devices from the point of use to the previous operation (customer to supplier)
- Purchase orders for your suppliers
- Work orders for your manufacturing area
- Visual communication tools
- Paperwork eliminators
Kanbans are not appropriate for:
- Single-piece or lot/batch production (for example, you would not try to set up a service part that you run five pieces per year on a kanban)
- Safety stock
- Systems that require suppliers to carry inventory and its associated carrying costs (lean is about win-win; consignment and other inventory “schemes” are not win-win).
- Long-range planning tools (changes in part number usage due to engineering changes, customer shifts in product usage or new product introductions must be handled by more traditional methods)
Launch your kanban initiative with no more than six to eight items that represent only one area of your facility. Make sure the organization knows about the kanban launch. When these items are flowing smoothly and organizational support for kanbans has increased, add more items and more areas.
Guidelines
1) Kanban implementation prerequisites include:
- Setup reduction (without setup reduction in place, order sizes are not reduced and we have what we do now – batch production)
- Levelized or uniform requirements/production (while there are techniques for kanbans to work in environments where demand is erratic, the kanban learning curve should start with fairly “uniform requirements”)
2) Certify your external suppliers. Certified means that a supplier’s deliveries are not subject to receiving inspection based on outstanding quality history. Supplier part kanbans which are rejected or placed “on hold” can severely disrupt the kanban.
3) Initially, paint all the totes, carts and other reusable containers one new and very visible color (I suggest bright green). This gives the kanban initiative great visibility to everyone in the organization during the launch period. It also gives your team an opportunity to easily spot any containers/signals that are out of place.
4) Use kanban supermarkets.
- Supermarkets are intermediate storage areas (at the customer) between the supplier and the customers (users) for that supplier.
- Supermarkets are used when there are multiple internal customers for an external supplier and/or multiple internal customers for an internal supplier.
- Supermarkets prevent the supplier from receiving a multitude of signals from all the organization’s internal customers for that supplier.
- With a supermarket, the internal or external supplier receives replenishment signals from only the customer’s supermarket.
Kanban Rules
1) Do not attempt to kanban an information product or physical part/product without the complete involvement of all the members of the value-added chain, including your external suppliers and customers! Remember, you cannot become a world-class enterprise without world-class suppliers.
2) Strive for quality at the source. Do not send defective information or physical products to your customer. Defects must be corrected immediately. Defective products will cause your customer’s line to shut down.
3) Kanbans require reliable equipment for support. Implement kanbans internally in areas where Total Productive Maintenance (TPM) is already in place.
4) Focus kanbans on products and part numbers with stable month-to-month delivery requirements and short setup and lead times. Concentrate setup reduction and raw material lead-time reduction efforts on the parts that have wide variations in month-to-month customer requirements.
5) All internal or external suppliers must have, or should be helped to develop, setup reduction programs. The true power of kanbans can be unleashed only when setup times do not influence manufacturing capacity and, therefore, lead time.
6) Suppliers should deliver all material directly to their customer (point of use). For suppliers who are not certified (incoming inspection required), the point of use should be taught to perform this inspection or the supplier should be replaced with a certified supplier.
7) Kanbans are not cast in cement – some experimentation is required. Be prepared to make adjustments initially as sales levels change or as other improvement activities reduce the required number of containers or kanban cards.
About the author:
Larry Rubrich is the president of WCM Associates LLC. For more information, visit www.wcmfg.com or call 260-637-8064.
