7 wastes of lean

The 7 wastes of lean (jap. muda) are the hidden costs of poor quality and management. Identification and removal of the waste is one of the most important principles of Toyota Production System and Lean manufacturing. The 7 wastes were first described by Taiichi Ohno, Toyota's Chief Engineer. The wasted referred originally to production. The description of wastes in services was created later.

The waste is everything that doesn't create a value for the customer. The customer wants good product. The company should manufacture if right first time without any additional costs. The customer doesn't want to pay for additional transport, storage or quality inspection.

Types of waste

There are two types of waste:

1. Activities that don't add value for the customer, but are necessary.
2. Activities that don't add value for the customer and are not necessary.

The first type of waste doesn't create value for the customer, however can be required by legislation or safety issues. The second type consists of 7 types of wastes.

7 wastes

The wastes below refer to production. See also: 7 wastes of services.

1. Overproduction

In order to assure good product for the customer, organization can manufacture more products. E.g. the quality level is 95%, which means that 5 out of 100 products are defected. In order to sell 100 good products, the organization has to manufacture more than 105 products (100 / 95% = 105,26). This additional production is waste of resources.

2. Inventory

The organization wants to be prepared for large customer orders. Therefore, it keeps some finished products ready for shipping, some work-in-progress near the workplaces and some raw materials. All of these freeze the capital, that could be used otherwise. Any more inventory than required in order to keep the flow of the process is a waste. The organization should apply e.g. Just in time to reduce it.

3. Defects

Each defect has to be evaluated. If the organization manufacture defected products, it need quality inspection. Products that cannot be repaired are waste. But also products that can be repaired are waste, because of additional time of workers and use of machines.

4. Motion

Any motion in the workplace which extends time of production or stops it is a waste. E.g.:

• searching for tools (see: 5S method),
• searching for raw materials,
• accidents during work.

5. Over-Processing

If the product has features that are not used by customers, creating them is waste. This should not limit creativity in design process, however the company should take into account needs of customers and evaluate which new features may create additional sales. Adding features that are not used increases costs of design, production, increases risk of defects. See also: designed quality.

6. Waiting

If the amount of raw materials and work-in-progress is too small, workers have to stop their work and wait. This waste is therefore related to 2. Inventory. However, there are also other situations when work is stopped, e.g.:

• machines out of order (see: Total productive maintenance),
• wrong harmonization of work - workplace have lower productivity than one next in process.

7. Transportation

Each move of raw materials, work-in-progress or finished products creates costs. Moreover, it is an occasion to damage the product. The production floor should be designed in such a way that reduces transportation to the minimum. The first workplace should be close to raw materials. Distance between the workplaces should be as low as the place for processed elements (output from one workplace and input to another). The last workplace should be close to the place where products are sent to customers.

Examples of 7 wastes of lean

• Overproduction: Producing more than is needed. For example, a company may produce extra inventory that is not required for sales, leading to additional costs for storage and handling.
• Transportation: Moving parts or products from one place to another, which adds no value. For example, if a customer orders a product from a remote warehouse, the cost of transporting the product to the customer would be considered a waste.
• Motion: Unnecessary motions of employees or machines. For example, if an employee has to walk to a different area to get a tool or material, this would be considered a waste.
• Waiting: Delays in production due to waiting for supplies or other operations. For example, if a machine is waiting for a part to be delivered, this would result in a delay and therefore be considered a waste.
• Inventory: Unnecessary inventory of finished goods or raw materials which adds unnecessary cost. For example, if a company is storing excess stock that is not needed, this would be considered a waste.
• Overprocessing: Doing more than necessary to fulfill customer requirements. For example, if a product is being tested more than necessary or if additional steps are being taken to complete a task, this would be considered a waste.
• Defects: Production or service of defective or incorrect products. For example, if a product is incorrectly assembled or if a service is not provided as promised, this would be considered a waste.

Advantages of 7 wastes of lean

The 7 wastes of lean identify and eliminate inefficiencies in production, services, and management processes.

• The 7 wastes of lean can help identify inefficiencies and areas where resources are being wasted.
• It can help to improve overall efficiency and reduce costs.
• It can lead to better decision-making and improved customer satisfaction.
• It can help organizations to identify areas where they can streamline processes and become more agile.
• It can help to reduce the amount of time wasted in non-value-adding activities.
• It can help to identify areas for improvement and develop better workflows.
• It can help to identify areas where communication and collaboration could be improved.

Limitations of 7 wastes of lean

The 7 wastes of Lean have been widely recognized as an invaluable tool for identifying problems in production. However, there are some limitations associated with the application of the 7 wastes in certain situations. These limitations include:

• The 7 wastes are focused on the manufacturing environment and may not be applicable to other industries. For example, the 7 wastes of lean are not suitable for use in the service industry.
• The 7 wastes are not comprehensive enough to identify all sources of waste. For example, they do not address issues such as customer complaints, employee motivation and engagement, and system failures.
• The 7 wastes are focused on process improvement, but do not address other aspects of quality and efficiency, such as product design and customer service.
• The 7 wastes do not provide concrete solutions to the identified problems. Instead, they provide general guidelines for identifying and addressing problems, but do not offer specific solutions.

Other approaches related to 7 wastes of lean

One of the main approaches related to the 7 wastes of lean is to identify and eliminate sources of non-value-added activities. Other approaches include:

• Kaizen: Kaizen is a Japanese term for continuous improvement, which is an essential part of lean production. Kaizen helps to identify and eliminate wasteful activities, reduce costs and improve quality.
• Heijunka: Heijunka is a Japanese term for production leveling, which is a key tool used in lean production to reduce waste. By leveling the production process, it is possible to eliminate waste and reduce cost.
• Takt time: Takt time is the amount of time available to produce a product. It is used in lean production to identify and eliminate waste by ensuring that the production process is running at the right speed.
• Just-in-time (JIT): JIT is a production system in which products are made to order and delivered just in time. JIT helps to reduce waste by eliminating the need to store products in inventory and ensuring that production is in line with customer demand.
• 5S: 5S is a system for organizing the workplace. It helps to reduce waste by eliminating clutter and creating an efficient working environment.

In summary, the 7 wastes of lean are a set of quality costs that can be identified and eliminated to reduce cost and improve production efficiency. Other approaches related to the 7 wastes include Kaizen, Heijunka, Takt time, Just-in-time and 5S, which are all important tools used in lean production.

7 wastes of lean — recommended articles

Lean manufacturing — Muda mura muri — Line balancing — Kanban methodology — 7 wastes of services — Just in time — Continuous process — Production cycle — Jidoka — Analogy and metaphor

References

• Imai M., (1997) Gemba - Kaizen, A Commonsense, Low-Cost Approach to Management, McGraw Hill Companies, Inc., New York 1997
• Imai M., (1986) Kaizen (Ky' zen) The Key to Japan's Competitive Success, McGraw Hill, Inc., New York 1986
• Womack J.P., Jones D.T. (2010) Lean Thinking: Banish Waste and Create Wealth in Your Corporation, New York:Free press

Author: Slawomir Wawak