Application de concepts Lean dans une opération d'entrepôt (document en anglais)

Applying Lean Concepts in a Warehouse Operation

Frank C. Garcia, P.E.

Director, Business Solutions & Engineering Services

Advent Design Corporation

Bristol, PA, USA

1. Introduction

This presentation shows how a warehouse operation can be improved using lean concepts and techniques.

Warehouse improvement requires optimizing material flow, order picking, replenishment, and dock operations.

Although many traditional lean techniques maybe difficult to apply, the concepts of improving material flow and

eliminating waste can be used to make significant improvement in warehouse lead time.

Many lean practitioners consider the term warehouse and lean to be mutually exclusive. However, regardless of how

fast inventory is turned, warehouses will always exist to allow a company to deal with variations in customer

demand. The key is to reduce the non-value added steps in the warehouse as much as possible and to improve

velocity and flow. Implementing a lean warehouse starts with value stream mapping. After the current state value

stream map is created, improvements can be easily developed to eliminate extra material handling, excessive travel

time, and time spent looking for products. Various lean improvement techniques such as material flow analysis,

quality improvement, and application of the 5Ss can be used. A warehouse improvement example is presented to

show how warehouse lead time, order picking time, and material handling can be reduced by 50% using lean

concepts.

2. Evaluating the Warehouse

Over the past few years the production areas have been upgraded without a corresponding enhancement of the

warehousing activities. Companies are now experiencing problems with the warehouse and distribution areas

keeping pace with the product as it is received from the various processing areas. Space utilization, material

handling, and data collection are just some of the challenges that arise. There has been a trend of increased labor to

support the warehousing requirements.

Where do you start? In order to understand where to start the implementation of lean concepts in the warehouse, one

of the most useful tools is the value stream map. The value stream is the set of all specific actions, both value added

and non-value added, that are needed to take a product through the information and production flows of a

manufacturing operation (1). The value stream map follows the production path from beginning to end and shows a

visual representation of every process in the material and information flows The maps show the linkage between

information flow and material flow for a product family. Most times the warehouse shows up on a value stream map as

simply an inventory triangle and shipping. This makes it difficult to evaluate the waste that is occurring within the

warehouse. It is necessary to show the process within the warehouse including operations such as receiving, palletizing,

putaway, order picking, order staging and preparation, truck loading, and shipping. A concept warehouse value stream

map is shown in Figure 1.

Simplified Warehouse Value Stream Map

Suppliers Customers

Production

Production and

Inventory Control

Warehousing

Shipping

Orders

Schedules

Lead Time

Orders

Orders

Figure 1

3. Warehouse Value Stream Map

The current state value stream map shows how the warehouse currently operates and serves as the foundation for the

future state changes. The map starts with the shipping area and works back through the warehouse process to the

production area and to the suppliers. You need to start with one product family otherwise the map will be too

complicated. It is also useful to track a product family order through the warehouse operation.

The production control information flow is shown to determine how the warehouse processes are being scheduled

and controlled. At the bottom of the map, the total process time and lead time are calculated for a typical product

family unit or order. Figure 2 shows a completed warehouse current state map.

The current state value stream map serves as the starting point for developing the future state. The current state

value stream map shown in Figure 2 revealed a number of opportunities to reduce lead time and processing time in

the warehouse, including the following:

• reduction in material handling time in order picking, putaway, and palletizing

• reliability issues with the strapping and metal detection machines

• reduction in truck loading time

• reduction in time spent checking inventory location and aging

Using the current state map, the goal in developing the future state map is to make the flow continuous and to

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