Calculating the Number of Kanban Cards
An automotive company has implemented a JIT program using kanbans to signal the movement and production of product. The average inventory levels have been reduced to where they are roughly proportional to the number of kanbans in use. Figure 5.8.4.1 shows the data for three of the products.
$$
\begin{array}{|c|c|c|c|c|c|c|}
\hline \text { Item ID. } & \text { Lead time } & \begin{array}{c}
\text { Length of } \\
\text { the } \\
\text { statistical } \\
\text { period }
\end{array} & \begin{array}{c}
\text { Usage } \\
\text { during } \\
\text { statistical } \\
\text { period }
\end{array} & \begin{array}{c}
\text { Number of } \\
\text { parts } \\
\text { (units) per } \\
\text { container }
\end{array} & \begin{array}{c}
\text { Safety } \\
\text { factor }(\%)
\end{array} & \begin{array}{c}
\text { Number of } \\
\text { containers } \\
\text { per } \\
\text { transport } \\
\text { batch }
\end{array} \\
\hline 1 & 36 & 20 & 600 & 200 & 0 & 1 \\
\hline 2 & 36 & 20 & 100 & 25 & 0 & 1 \\
\hline 3 & 36 & 20 & 50 & 10 & 0 & 1 \\
\hline
\end{array}
$$
Fig. 5.8.4.1 Data on three products for calculation of the number of kanban cards.
a. The process engineers have been hard at work improving the manufacturing process. They have initiated a new project to reduce lead time from 36 days to 21 days. What would the percentage change in average inventory be for each item?
b. Calculate the number of kanban cards using other data values. Try to answer the following questions:
- What is the minimum number of kanban cards required in any case?
- How do the safety factor and the number of containers per transport batch influence the number of kanban cards required?