How to Implement a Replenishment Pull System Using Kanban

Darren Dolcemascolo
Tags: inventory management

Pull is one of the key principles of lean thinking. There are essentially two different types of pull systems: sequential pull and replenishment (or supermarket) pull. In sequential pull, the downstream customer pulls parts from the upstream supplying process in the sequence in which the supplying process produces; that is, the supplying process dictates the sequence of work.

Sequential pull limits the amount of inventory between the two processes. In replenishment pull, the downstream customer pulls from a supermarket according to what it needs (based on a schedule dictated by its customer). The supermarket is replenished by the supplying process. In this article, I will describe a case study in which a California manufacturer implemented replenishment pull between an injection-molding operation and two assembly cells.

The company in question had 12 plastic injection-molding machines. Each produced a number of components that were assembled into a finished product by the assembly cells. Before the implementation, the company had approximately 10 days of injection-molded inventory (work in process, or WIP). There were also a significant number of material shortages affecting the productivity of the assembly cells.

A kaizen team was formed, consisting of a materials person, assembly and injection-molding operators, an industrial engineer, an area supervisor, and a few employees from outside the area. After spending day one in training and mapping out the current state process, the team discovered significant waste in the process:

After analyzing material usage and variability in usage, the team created and properly sized a supermarket of plastic materials. The system would work as follows:

The new system resulted in a 90 percent reduction in shortages and 70 percent reduction in WIP (from 10 days to three days).

About the author:
Darren Dolcemascolo is an internationally recognized lecturer, author and consultant. To learn more, visit or call 866-559-5598.