One of the primary goals of Lean manufacturing is to eliminate waste in a process. Waste is any effort or expense that is not adding value for the customer. It can come in the form of material, time, or labor waste. In Lean thinking, the primary sources of waste are broken down into what we refer to as the 8 wastes of Lean.
By the end of this article, you will have a clear understanding of each of the 8 wastes. You will also be able to identify examples of these forms of waste, not only in a manufacturing environment, but also in your daily life. Once you are able to recognize waste in your life, you can take action to reduce these wastes in order to be more productive and achieve any goal faster.
A History of the 8 Wastes in Lean
The concept of defining manufacturing wastes originated with the Toyota Production System. In Japanese, these wastes are referred to as muda which means futility or wastefulness. Toyota engineer, Taiichi Ohno defined the 7 categories of muda as follows:
- Transportation
- Inventory
- Motion
- Waiting
- Overproduction
- Over-processing
- Defects
Therefore, the 7 wastes are commonly referred to by the acronym “TIMWOOD”.
Later on, the 7 wastes were expanded to the 8 wastes with waste due to non-utilized talent or skills added in. Therefore, the acronym was expanded to “TIMWOODS”.
Alternatively, I prefer to use the acronym “DOWNTIME” to refer to the 8 wastes of Lean. In this case, the 8 wastes are ordered as follows:
- Defects
- Overproduction
- Waiting
- Non-Utilized Talent
- Transportation
- Inventory
- Motion
- Excess Processing
In manufacturing, downtime is viewed as a negative part of any process and is often the result of one or more of the 8 wastes. Therefore, I find this acronym to be easy to remember and provide some context to the 8 wastes in Lean.
What are the 8 Wastes in Lean?
1. Defects
What is Defect Waste?
Defects are caused when a product does not meet a customer’s required specifications. This can lead to material waste if the defective product needs to be scrapped. It can also cause time waste if the defective product must go through a rework process to achieve the customer specifications. Therefore, both scrapping and reworking the product negatively impacts the manufacturer, as well as the customer, due to decreased yields, increased manufacturing costs, and increased lead times.
Causes of Defects
There are many potential causes for defects in a manufacturing process but a few are:
- Misunderstanding of the customer’s requirements
- Insufficient documentation for how to achieve the desired product specifications
- Inadequate control systems for detecting defects quickly
How to Eliminate Defects
Based on these causes, the steps to eliminate defects are relatively straightforward. They are:
- Documentation of customer specifications
- Implementation of standard work to ensure the process is consistent
- Introduction of control systems to the process to ensure that operators are able to detect defects quickly
Example of Defects in Manufacturing
An example of defects in manufacturing is when an operator generates large amounts of scrap on a product because they do not have the correct processing parameters defined. A company can avoid this by implementing clear documentation and standard work for the process.
Example of Defects in Daily Life
Defects or mistakes are very common in daily life. For example, everyone has probably experienced a cooking mishap at some point in their life. I know I have definitely made the mistake of missing a crucial ingredient in a recipe or accidentally cooking something for too long in the microwave. These mistakes almost always end with me needing to throw away the food and remake it which causes both material and time waste.
2. Overproduction
What is Overproduction Waste?
The next of the 8 wastes in Lean is overproduction which refers to producing more material than required by the customer. When a manufacturer overproduces, they are operating under a push system, which uses a “Just-in-Case” mindset, rather than a pull system, which uses a “Just-in-Time” mindset.
One of the five principles of Lean methodology is introducing a pull system. This is due to the fact that overproducing material can directly lead to many of the other 8 wastes. For example, overproduction can directly increase defect waste, inventory waste, and transportation waste as follows:
- Defect Waste: Overproducing can hide defects in “work in progress” (WIP) material. This will result in more material needing to be scrapped out or reworked during a later stage in the process.
- Inventory Waste: Overproducing leads to increased inventory of WIP and finished goods which leads to increased storage costs. Excess inventory also increases the chances that the customer will not have a need for all of the material produced. Therefore, you will have excessive material waste due to not being able to sell the material.
- Transportation Waste: Increased inventory due to overproduction also leads to transportation waste since employees will likely need to stage and move the excess inventory additional times.
Causes of Overproduction
In general, overproduction results when a manufacturer operates under a push system. Companies typically use a push or “Just-in-Case” system when there is idle personnel or equipment. Manufacturers might also lean towards this production method when the process has long setup or changeover times. Therefore, to limit the number of setups or changeovers, they will produce as much material as possible all at once regardless of how much the customer is asking for.
How to Eliminate Overproduction
To eliminate overproduction, companies must address the reasons why they are operating under a push production system.
For example, you can implement a Takt time. Takt time is the amount of time required to complete each product unit in order to meet the customer’s demand.
T = Ttotal / D where
T = Takt time
Ttotal = the total amount of production time available for the order
D = customer demand
By implementing a Takt time for each step in the production process, you will be able to balance the rate of production between each step. This will reduce the possibility of idle personnel or equipment.
Companies may also need to look into ways to reduce their setup and changeover times. This will ensure that they do not have to overproduce in order to avoid creating massive amounts of downtime setting up the equipment for a new product run.
Example of Overproduction in Manufacturing
An example of overproduction in a manufacturing environment is when a food company produces 100,000 packages of a perishable food when they only have an order for 50,000. This results in them needing to throw away the other 50,000 packages of food a few weeks later when they spoil.
Example of Overproduction in Daily Life
An example of overproducing in daily life is making more copies of a document than necessary.
3. Waiting
What is Waiting Waste?
Waste due to waiting is caused when equipment or people are idle. This increases labor and overhead costs which will negatively impact company margins. Also, if an equipment maintenance issue is causing the waiting, a company may incur additional costs around expediting a replacement part to fix the issue.
Waiting waste can also directly lead to some of the other 8 wastes in Lean, such as defect waste and inventory waste, as follows:
- Defect Waste: If production falls behind due to waiting time, you may feel pressure to “catch up”. In doing so, you may take shortcuts which lead to the accidental production of additional scrap or rework material.
- Inventory Waste: Equipment downtime can lead to increased inventory of WIP and raw materials.
Causes of Waiting
In a manufacturing environment, waiting can occur for a variety of different reasons. Some of these reasons include:
- Required equipment maintenance
- A product setup or changeover is occurring
- The raw materials or WIP required for the process are not on-hand
- Poorly trained staff needing to wait for instructions
- Insufficient staffing
How to Eliminate Waiting
Since there are many different causes of waiting waste, there are also many different methods for eliminating it. The proper method to use will depend on the cause. These methods can include:
- Implementing a schedule for preventative maintenance procedures.
- Investigating ways to reduce changeover and setup times
- Introducing a pull system. This requires that raw material purchases are appropriately scheduled, and that the Takt time for each process is balanced as discussed in the previous section on overproduction waste.
- Creating detailed SOPs for each task and enforcing training to these procedures.
- Ensuring that the company hires the appropriate amount of staffing to fill the desired production time
Example of Waiting in Manufacturing
An example of waiting in manufacturing is when the staff operating the equipment is not trained on how to react to a specific quality issue. In this case, the staff may discover that the product they are running has a defect, but they are unclear on what steps to take to resolve the issue. Therefore, they may need to shut down the process and wait for input from engineering on how to troubleshoot the issue.
Organizations can resolve this by implementing procedures, such as troubleshooting guides, which detail specific steps to take to resolve each quality issue that may occur.
Example of Waiting in Daily Life
An example of waiting in daily life is when you send an email to a professor asking for clarification on an assignment and need to wait for their response before moving forward.
4. Non-Utilized Talent
What is Non-Utilized Talent Waste?
Non-utilized talent waste is the most recently added of the 8 wastes in Lean. This form of waste refers to management failures more so than manufacturing failures. Overall, wasting talent or human potential can lead to employee disengagement and turnover. Therefore, it can be very expensive for the company because they may need to repeatedly train new employees since they are unable to retain their current ones.
Causes of Non-Utilized Talent
Some of the causes of non-utilized talent waste include:
- Poor training
- Management not engaging with frontline workers to leverage their expertise
- Not involving all employees in process developments or changes
- Employees not having time to develop new skills
- Employees constantly needing to “fight fires” rather than using skills for continuous improvement
How to Eliminate Non-Utilized Talent
The primary way to eliminate non-utilized talent waste is to change the culture of the organization. In Lean thinking, the culture of a company should revolve around continuous improvement with every employee engaged in the process. One Lean tool that companies can use to promote this is Gemba walks. Gemba walks are when management takes some time each morning to walk the manufacturing floor, speak with the employees, and learn more about the process. This gives the frontline workers the opportunity to voice their thoughts on current problems and give suggestions for improvement.
Companies can also avoid non-utilized waste by supporting employees in developing new skills. This could mean ensuring that proper training is in place for all job roles, but it can also refer to tuition reimbursement programs for further education.
Example of Non-Utilized Talent in Manufacturing
An example of non-utilized talent in manufacturing is when management completes a new process development, such as changing the process flow, without engaging any of the frontline workers. In this case, the frontline workers have daily experience with the process and can provide valuable insight on any oversights in the new development. If the company does not take their opinions into account, there is a good chance the new development will not be optimal. Therefore, this can lead to wasted time and potentially additional scrap or material waste.
Example of Non-Utilized Talent in Daily Life
An example of non-utilized talent in daily life is when you attempt to determine a good investment portfolio alone when your partner is a finance expert. Therefore, your partner is better suited for the task and not involving them in the process is a waste of their skills.
5. Transportation
What is Transportation Waste?
Another one of the 8 wastes in Lean is transportation waste. This form of waste occurs when raw materials, WIP, equipment, tools, or people need to be moved around the manufacturing facility excessively which leads to wasted time. Transportation waste can also lead to higher overhead costs due to forklift drivers needing to perform excessive tasks. This will also lead to increased wear and tear on equipment such as the forklifts.
Transportation waste can also directly lead to some of the other 8 wastes such as defect waste and waiting waste as follows:
- Defect Waste: During transportation, there is an increased risk that materials or products will be damaged.
- Waiting Waste: Equipment downtime may increase as operators need to wait for the required raw materials or WIP to be transported to the process area.
Causes of Transportation Waste
The two primary causes for transportation waste include:
- Overproduction of materials
- Poor process flow
How to Eliminate Transportation Waste
In the case that overproduction is the cause of transportation waste, you can eliminate it by following the same steps outlined in the earlier section on overproduction waste. For example, you can balance the Takt time between process steps to ensure that the process is not creating excess WIP. You should also investigate how to reduce any setup and changeover times to ease the need to produce large quantities of a product all at once.
For transportation waste caused by poor process flow, you can improve this through value stream mapping. Value stream mapping is a Lean tool that you can use to outline each step taken in a process. Once you create this outline, you should then determine the non-value add steps in the process. Non-value add steps are any that do not directly supply value to the customer. Once you determine these steps, you should reduce all necessary non-value add steps and eliminate all unnecessary non-value add steps.
Example of Transportation Waste in Manufacturing
An example of transportation waste in manufacturing is when a process has poor flow, such as that shown in the example below. In this case, the packaging department is far from both the WIP storage area and the shipping area. This means that employees will need to transport both the WIP material and the packaged material an excessive distance. This transportation waste could be reduced by relocating the packaging equipment to be in between the WIP storage and the shipping department rather than on the other side of the facility.
Example of Transportation Waste in Daily Life
An example of transportation waste in daily life is if you go to the grocery store on the other side of town versus the one two minutes from your house even though you can purchase the same ingredients at both locations.
6. Inventory
What is Inventory Waste?
Inventory waste refers to the time and material waste accrued from storing large quantities of raw materials, WIP, and finished goods. Inventory is very expensive. There are several reasons for this which we can correlate to some of the other 8 waste categories:
- Defect Waste: Products with a shelf life may end up as waste if customers do not purchase them quickly enough.
- Transportation Waste: The storage costs associated with storing inventory are high, and high inventory levels mean that items will likely need to be staged and moved several times.
Causes of Inventory Waste
There are a variety of different causes of inventory waste with some coming directly from the other 8 waste categories. Some of these include:
- Overproduction
- Waiting time, such as machine downtime, which leads to higher raw material and WIP inventory
- Poor communication between the purchasing and scheduling teams
How to Eliminate Inventory Waste
Since overproduction often causes excess inventory, you can eliminate inventory waste using the same methods as those described in the earlier section on overproduction. For example, you should balance the Takt time between process steps, and reduce setup and changeover times.
Inventory can also be reduced by improving communication across an organization. This can allow production to act as a pull system where material is produced “Just-in-Time” rather than a push system where material is produced “Just-in-Case”.
Example of Inventory in Manufacturing
An example of inventory waste in a manufacturing environment is when a company produces twice the amount of material than necessary to fulfill an order. This leads them to need to pay higher storage costs for the excess material.
Example of Inventory in Daily Life
An example of inventory waste in daily life is if you buy too much of a perishable food while grocery shopping. This can lead you to not use all of the food before it spoils. Therefore, you are wasting food and money throwing spoiled food away.
7. Motion
What is Motion Waste?
Motion waste is any unnecessary movement in a process, such as bending, reaching, lifting, walking, or moving. By laying out the workspace in a way that eliminates the need for these unnecessary movements, there will be both time savings and potential health and safety gains. For example, eliminating a repeated motion, such as bending over to lift a heavy box, will reduce the risk of employee back strain.
Causes of Motion Waste
The primary cause for motion waste is a poorly designed workspace for process flow.
How to Eliminate Motion Waste
One of the five principles of Lean manufacturing is to develop flow for a process. Therefore, there are many Lean tools that can assist with this. For example, 5S is an organizational method that revolves around ensuring that only necessary materials and tools are located in a given workspace and that each of these items is always located in the optimal position for efficiency. This means that tools should not be located in places that require repeated bending or reaching to grab them as this will lead to motion waste.
Some other Lean tools that you can use to document the ideal process flow and determine areas for improvement are spaghetti diagrams, standard work, and value stream maps.
Example of Motion Waste in Manufacturing
An example of motion waste in manufacturing is if the tool required for a specific task is located beneath a workbench. This would require the employee to repeatedly bend over to retrieve the tool. You can eliminate this motion waste by completing a 5S exercise where you relocate the tool to an optimal position within easy reach.
Example of Motion Waste in Daily Life
An example of motion waste in daily life is when the vacuum that you use on the carpet on the second floor of your house is located in a closet on the first floor. Therefore, whenever you want to vacuum, you have to move the vacuum upstairs which leads to wasted time. You could eliminate this by finding a place to store the vacuum on the second floor where you use it.
8. Excess Processing
What is Excess Processing Waste?
The final of the 8 wastes of Lean is excess processing. This form of waste occurs when additional, non-value add steps are completed during a process. This goes directly against the core principles of Lean thinking because it does not focus on the needs of the customer.
Causes of Excess Processing
Some causes of excess processing include:
- Miscommunication that results in a task being duplicated, such as data entry or approval processes
- Over-engineering a solution to a problem
- Focusing on higher precision than necessary
How to Eliminate Excess Processing
The best way to eliminate excess processing waste is to complete a value stream map. You should establish a cross-functional team to complete the value stream map so that it captures all details and perspectives of the process. Once the map is complete, the team can identify the non-value add steps in the process and determine ways to reduce or eliminate them.
Example of Excess Processing in Manufacturing
An example of excess processing in manufacturing is when you test a product for a quality parameter that is not important to the customer. In this case, you are completing extra work that does not add value for the end customer.
Example of Excess Processing in Daily Life
An example of excess processing in daily life is if there is miscommunication between you and your partner about who is going to complete your monthly budget. This could result in both of you doing the work which would be an unproductive duplication of efforts.
Conclusion
Overall, these 8 waste categories in Lean methodology cover the vast majority of waste that you can experience either in a manufacturing environment or in daily life. As you have seen throughout this article, many of the 8 wastes are interconnected. Therefore, it is vital to keep all areas in mind when working to reduce waste. For example, if you focus on eliminating causes of inventory waste you will also need to address overproduction issues in your process.
By keeping these main waste categories in mind on a daily basis, you can work towards massive reductions in both time and money waste. This can directly lead to huge productivity gains which will allow you to achieve your goals much more efficiently and successfully.
Do you recognize any other situations in your life that fall into one of the 8 waste categories? I’d love to hear from you in the comments below!
