# 6.8.4 Exercise: Calculating the Number of Kanban Cards

### Intended learning outcomes: Present data on three products for calculation of the number of Kanban cards. Calculate the required number of Kanban cards before and after the process improvement.

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 6.8.4.1 shows the data for three of the products.

Fig. 6.8.4.1        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?

Solution: Using the formula in Figure 6.3.2.3, calculate the required number of Kanban cards before and after the process improvement. As inventory is proportional to number of Kanbans, the inventory reduction corresponds to the reduction of the number of Kanban cards.

• Item 1:           before,   7; after, 5     -->      Inventory reduction: 29%
• Item 2:           before,   9; after, 6     -->      Inventory reduction: 33%
• Item 3:           before, 10; after, 7     -->     Inventory reduction: 30%

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?

## Course section 6.8: Subsections and their intended learning outcomes

• ##### 6.8.1 Exercise: Operation Time versus Operation Cost, or the Effect of Varying Setup Time and Batch Size

Intended learning outcomes: Explain the need to find a balance between short lead time, and low cost, for any operation. These two factors are determined by setup time and batch size.

• ##### 6.8.2 Exercise: The Effect of Cellular Manufacturing on Lead Time Reduction

Intended learning outcomes: Present the routing sheet for production of shafts. Explore the effect of cellular manufacturing on lead-time reduction.

• ##### 6.8.3 Scenario: Line Balancing — Harmonizing the Content of Work

Intended learning outcomes: Present the routing sheets for parts production out of sheet metal of three products. Explain possible ways for line balancing through harmonizing the content of work.

• ##### 6.8.4 Exercise: Calculating the Number of Kanban Cards

Intended learning outcomes: Present data on three products for calculation of the number of Kanban cards. Calculate the required number of Kanban cards before and after the process improvement.

• ##### 6.8 Scenarios and Exercises

Intended learning outcomes: Operation time versus operation cost: disclose the effect of varying setup time and batch size. Calculate the effect of cellular manufacturing on lead-time reduction. Perform line balancing through harmonizing the content of work. Determine the number of Kanban cards.