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Lean

Environmental Professional’s Guide to Lean and Six Sigma: Chapter 2

What Is Lean?

What is Lean Manufacturing?

The term “Lean,” coined by James Womack, et al. in the 1990 book, The Machine that Changed the World, describes the manufacturing paradigm Key Termestablished by Toyota. Lean manufacturing or Lean production refers to a collection of principles and methods that focus on the identification and elimination of non-value added activity (waste) involved in producing a product or delivering a service to customers. In the Lean context, waste is any activity that does not lead directly to creating the product or service a customer wants when they want it.

Seven “Deadly” WastesBox 8 lists seven “deadly” wastes that Lean commonly targets. With the rise of environmental and social consciousness, some companies are expanding the definition of Lean (see Box 9).

Expanding the Definition of Lean

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Creating a Lean Culture

Lean manufacturing embodies several important principles as well as a collection of tactical methods for achieving them. These principles and methods effectively engage employees in a continuous improvement culture that naturally encourages waste minimization and pollution prevention. Key Lean principles include:

  • Let customers pull value through the enterprise by understanding what the customer wants and producing to meet real demand.
  • Pursue perfection by working to continually identify and eliminate non-value added activity (waste) from all processes.
  • Involve employees in continual improvement and problem-solving activities.
  • Implement a rapid plan-do-check-act improvement framework to achieve results fast and to build momentum (e.g., “try-storming” in kaizen events).
  • Use metrics and rapid performance feedback to improve real-time decision-making and problem-solving.
  • Approach improvement activities from a whole enterprise or system perspective.
  • Emphasize learning at an organizational level through sharing of best practices from one project to another. In Japanese, this is called yokoten.

Lean can be considered a combination of management system (governance), organizational culture, and continual improvement tools (see Figure 2.1).

Model of a Lean Learning Organization

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History of Lean Activity

After World War II, the Toyota Motor Company, with the help of Japanese engineers Taiichi Ohno and Shigeo Shingo, pioneered a collection of advanced manufacturing methods that aimed to minimize the resources it takes for a single product to flow through the entire production process. Inspired by concepts developed by Henry Ford in the early 1900s, Toyota created an organizational culture focused on the systematic identification and elimination of all waste from the production process, called the Toyota Production System (TPS).

The TPS “house” (Figure 2) has become a common symbol of Lean. The roof represents the customer-oriented goal of Lean: to provide the highest quality products and services, at the lowest cost, with the shortest lead time. At the core of the “house” is the involvement of all employees in a culture of continual improvement. The pillars are just-in-time production and jidoka (built in quality), while the foundation is standardization. The individual tools and terms listed in the TPS house are defined below and in Appendix C.

Toyota’s success has led thousands of other companies across numerous industry sectors to tailor these advanced production methods to address their operations.

Toyota Production System House

Status of Lean Activity in the United States

In the U.S., Lean implementation began in the 1980s in the automotive and aerospace sectors. Today, numerous companies of all sizes and across multiple sectors are implementing Lean production. According to the 2007 IndustryWeek/Manufacturing Process Improvement Census of Manufacturers, nearly 70 percent of all U.S. plants have adopted Lean manufacturing as an improvement methodology.1

U.S. Sectors Implementing Lean

Examples of U.S. manufacturing sectors where there is significant Lean activity include the following. (Implementation of Lean is not limited to these industries, however.)

  • Aerospace
  • Appliances
  • Automotive
  • Banking
  • Construction
  • Electronics
  • Furniture
  • Government
  • Medical devices
  • Shipbuilding & Repair

Although it originated in manufacturing, Lean production has been rapidly expanding to service industries, including healthcare, banking, insurance, and even government agencies. Over the past five years, about 20 state environmental agencies have used Lean methods to improve permitting and other agency processes.

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Lean Tools

There are a variety of common methods in the Lean toolbox, many of which are defined in Table 1 and displayed in the “Lean Tactical Tools” diagram in Figure 3. Each of these tactical methods has clearly defined process steps, techniques, and desired outcomes. Most Lean tools are implemented in short bursts of activity that include focused and intensive planning and implementation phases. In this context, there is a strong bias toward implementation, as opposed to prolonged planning. This fits within the continual improvement philosophy that emphasizes making changes to address problems and eliminate waste, tracking performance, and making additional changes to further increase performance.

Selected Lean ToolsLean Tactical ToolsBecause of their importance to understanding Lean, three methods—VSM, kaizen events, and 5S—are described in more detail below.

Value Stream Mapping

Key TermValue stream mapping (VSM) refers to the process of developing a high-level visual representation of the activities involved in delivering a product or service (a “value stream”) to customers (see example in Figure 4). Value stream mapping is shown as the “staircase” in the house of Lean toolbox above because Lean practitioners use value stream mapping to prioritize and select Lean implementation projects. Lean practitioners use value stream mapping to:

  • Identify major sources of non-value added time in a value stream
  • Envision a less wasteful future state
  • Develop an implementation plan for future Lean activities

Value Stream MapThe typical results of a 2 to 5 day value stream mapping event are two maps—a “current state” map of the targeted process (see Figure 5) and a “future state” map of the desired process flow (i.e., what you want the process to look like). An implementation plan for how you are going to get from the current state to the future state is also developed. Because value stream maps help highlight the sources of waste, they enable an organization to target Key Pointfuture kaizen improvement events on specific processes or process steps in the value stream to help move toward the desired “future state” value stream map. Value stream mapping is the most foundational tool in the Lean toolset. As the map is developed, the team as a whole is able to recognize and validate what is actually happening in a process.

Current State MapKey PointThe power of value stream mapping lies in walking the plant floor, talking to workers, and closely observing how a product is actually made from start to finish. This is an excellent way to identify waste and non-value added activity in the value stream, including excess work in process, which can represent the majority of lead time.

Kaizen Events

Lean production is founded on the idea of kaizen, or continual improvement. Kaizen is a combination of two Japanese words that mean “to take apart” and “to make good.” The kaizen philosophy implies that small, incremental changes routinely applied and sustained over a long period result in significant improvements. Lean is typically implemented through kaizen events, which are 2-5 day rapid process improvement events. Kaizen events are a key method used to foster a culture of continual improvement and waste elimination and are often used to implement other Lean methods. Box 10 provides an overview of kaizen event. Preparation of a value stream map is an important component of kaizen pre-event planning.

Kaizen Event OverviewThe kaizen strategy aims to involve workers from multiple functions and levels in the organization in working together to address a problem or improve a particular process. The team uses analytical techniques, such as process maps, to quickly identify opportunities to eliminate waste in a targeted process. The team works to rapidly implement chosen improvements (often within 72 hours of initiating the kaizen event), typically focusing on solutions that do not involve large capital outlays. Periodic follow-up events aim to ensure that the improvements from the kaizen “blitz” are sustained.

5S

5S is a systematic, five-step process for developing and maintaining a clean and orderly workspace. 5S derives from the belief that, in the daily work of a company, routines that maintain organization and orderliness are essential to a smooth and efficient flow of activities. The 5S pillars help create a productive work environment and create the foundation for implementing more advanced Lean methods such as cellular manufacturing and just-in-time production.

The 5S’s are:

  • Sort (Get rid of it): Separate what is needed in the work area from what is not; eliminate the latter.
  • Set in order (Organize): Organize what remains in the work area.
  • Shine (Clean and solve): Clean and inspect the work area.
  • Standardize (Make consistent): Standardize cleaning, inspection, and safety practices.
  • Sustain (Keep it up): Make 5S a way of life.

Implementation of this method “cleans up” and organizes the workplace, and it is typically the starting point for shop-floor transformation. A typical 5S project would result in significant reductions in the square footage of space needed for existing operations. It also would result in the organization of tools and materials into labeled and color coded storage locations, as well as “kits” that contain just what is needed to perform a task. Sometimes companies add a 6th “S” for safety (see Figure 6). Figures 7 and 8 are before and after 5S photos.

5S + Safety DiagramPhoto Taken Before 5SPhoto Taken After 5S

How Lean Factories Differ from Traditional Manufacturing Environments

Traditional U.S. manufacturing facility layouts are set up in what is called a “batch and queue” production systems (see Figure 9). Batch and queue production entails the use of large machines, large production volumes, and long production runs. Each department is designed for one specific purpose and completed products cannot move on to the next functional department until the entire “batch” has been processed. In contrast, cellular manufacturing is a workplace-design approach in which manufacturing work centers (or cells) have the total capabilities needed to produce an item or group of similar items. Figure 10 displays the product-aligned, one-piece flow, “pull” production system that cellular manufacturing systems are based on.

Example Plant Layout for Traditional “Batch and Queue” ProductionExample Structure of a Lean Manufacturing Cell for a Single ProductIn cellular manufacturing systems, properly trained, semi-independent work cells are flexible and responsive. Defects and other manufacturing issues can be managed more efficiently than work centers set up on the basis of similar equipment or capabilities, where items must move among multiple work centers before they are completed. Table 2 compares Lean manufacturing and traditional manufacturing characteristics.

Comparing Lean and Traditional ManufacturingLean production typically represents a paradigm shift from conventional “batch and queue,” functionally-aligned mass production to “one-piece flow,” product-aligned pull production. This shift requires highly controlled processes operated in a well maintained, ordered, and clean operational setting that incorporates principles of just-in-time production and employee-involved, system-wide, continual improvement.

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Where to Find More Information on Lean

There are numerous publications, training programs, and websites that provide information on Lean principles and Lean methods. For a list of resources, please see Appendix A, Lean and Six Sigma Resources.

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Footnotes

1 Blanchard, David. “Census of U.S. Manufacturers–Lean Green and Low Cost,” IndustryWeek (October 2007).

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Toolkit Navigation

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