Have you ever watched a relay race? Each runner gives the best of his performance for his portion of the race, and passes the baton to the next runner in a predefined area.
In a 4x100m relay, to pass the baton there is a 20m transmission zone: 10m before the 100m, and 10m after. This zone is materialized on the ground, to allow the athletes to adjust their actions. Passing the relay before or after this zone is eliminatory.
This 20m zone for each 100m section thus represents 20% of the distance travelled.
Wait a bit (at least a few tenths of a second…).
In our supply chains, we naturally ask each of the players (suppliers, factories, distribution centers) to give their best performance, but then to hand over the baton at a given date or even time, very precisely. Is that right?
If, for example, we assemble complex systems with multiple components made to order, we require all partners to deliver just in time for integration of the final system.
In other words, over-trained athletes are entitled to a 20% time zone to pass the baton, but in the supply chain planning the date must be strictly adhered to and any delay or advance is an anomaly
A Time Buffer
In the real life of our companies this handover also requires flexibility, the definition of transmission zones, and an adapted decision making (slow down / speed up) in view of our position in this zone.
Let’s call it a time buffer. A time buffer is very similar to an area where relays pass between upstream and downstream operations. It is there to absorb the variability of the upstream operations, and to allow the downstream operation to start in time. This time buffer is materialized with red, yellow and green zones, and depending on our position in the buffer we make steering decisions: speeding up, slowing down, giving priority to this order rather than that one.
When you are manufacturing to order, the organization of time buffers at key points of your flows, their proper sizing, and their visual control are essential to ensure fluid relays along your supply chain.