# Kapitel 6 – Das Lean-/Just-in-time-Konzept und die Wiederhol­produktion

## Section 6.2.1: Lead Time Reduction through Setup Time Reduction and Batch Size Reduction — Setup-Friendly Production Facilities

### Intended learning outcomes: Identify the simplest formula for operation time. Produce an overview on setup-friendly production facilities.

The following exercise helps to illustrate the need to find a balance - for any operation - between short lead time and

1. low cost.These two factors are determined by setup time and batch size. Find the effect of setup time and batch size on the operation time, which is a measure ot the lead time of the order
2. the time per unit (that is run time plus the setup time divided equally to each unit), which is a measure of the cost of the operation, and therefore of the cost of the production or procurement order.

## Section 6.2.1: Lead Time Reduction through Setup Time Reduction and Batch Size Reduction — Cyclic Planning and “Heijunka”

### Intended learning outcomes: Present in detail cyclic production planning and leveling of the production (“heijunka”).

Exercise: Try to find a sequence of parts A, B, C and D with a minimum setup time. For creating a sequence, drag parts to the empty circles. The result is called a basic cycle.

## Section 6.2.2: Lead Time Reduction Through Production Segmentation, or Manufacturing Segmentation

### Intended learning outcomes: Produce an overview on production segmentation, or manufacturing segmentation.

Exercise: Try to find a production segmentation that minimizes transport distances:

## Section 6.2.2: Lead Time Reduction Through Cellular Manufacturing and One-Piece Flow

### Intended learning outcomes: Explain cellular manufacturing, one-piece flow, and the formula for lead-time calculation with cellular manufacturing.

Exercise: The following is a possible routing sheet for shaft production. Look at the difference between the lead time for job-shop production and the lead time with cellular production. Also, look at the difference between the theoretical minimum lead time in this particular case and the maximum lead time for cellular manufacturing, as well as at the difference between the actual minimum lead time and the lead time that entails the minimum load (or miminum allocated time for the operation, that is operation time plus wait time between the units of the batch) at the workplaces. By modifying setup and run times of the operations, change the cell driver. Try to find a situation where the value for minimum total lead time tends towards the theoretical maximum lead time for cellular manufacturing.

To understand this formula intuitively, consider the following: The longest operation, the so-called cell driver, provides the minimum lead time. The other operations overlap. Lead time then increases at most by setup and one run time per unit of all other operations. In concrete cases, lead time will fall at some point between the minimum and the maximum.

## Section 6.2.6: Generally Valid Advantages of the Lean / Just-in-Time Concept for Materials Management

### Intended learning outcomes: Describe the effect of forecast errors through the combining of requirements in batches across many production structure levels. Explain the effect of longer and shorter lead time on the (customer) order penetration point.

The following exercise illustrates the effect of lead time reduction explained before.
Drag the stocking level to the left, then to the right, and watch the delivery times and stocking levels change. Then apply JIT techniques ("after JIT") and find the differences.

## Section 6.3.1: Kanban — A Technique of Execution and Control of Operations

### Intended learning outcomes: Describe the Kanban card. Explain the Kanban feedback loop. Present in detail Kanban rules of order release and control of the feedback control system.

Watch the animation demonstrating the basic principle of the kanban technique explained in Figure 5.3.1.3. In this exercise, five containers form one transport batch.

## Case Study: Doing Things Right

Working on this case study will give you the opportunity to put the knowledge you have gained about flow-oriented processes into practice.

The concepts introduced in the case study are more than just processes for the planning and control of production. These concepts have caused far-reaching changes in production science, changes that require a rethinking, not only in production but in the entire company – from purchasing to sales and from the executive level to the employees in the factory. Today, these changes are known as lean production. Just-in-time, lean management, kaizen and other methods and philosophies are also components of lean production.