The 8 Wastes of Lean Manufacturing

Dealing with inefficient processes can offer a company an easier path to higher profits than increasing revenue. As a result, more companies are looking to lean manufacturing for solutions.

The objective of lean manufacturing is to increase product value while decreasing the resources, time, and effort needed to manufacture and deliver the product to the customer. Removal of waste is required to achieve this.

There are 8 forms of waste under the lean manufacturing model. We’ll be offering a run-down of these wastes and showing how each directly and indirectly impacts your company’s bottom line. We’ll also show how lean manufacturing enables you to deal with each type of waste.

The 7 Original Wastes of Lean Manufacturing

The Toyota Production System that inspired lean manufacturing had seven types of waste. These are explained in detail below.

Overproduction

Overproduction is when more products or parts are produced than are needed in subsequent processes. It is often described as the worst form of waste in lean manufacturing because it has a snowball effect and can lead to excess inventory, transportation waste, and defects.

Scenario: Excess parts have been produced in one process

The excess parts will have to be stored until they can be used. These will be kept in a warehouse as inventory and moved back to the production line later. The excess inventory will put pressure on downstream processes to be faster leading to defects.

If the overproduced parts have defects, these will be caught late and the number of parts that need rework or additional post-processing will be very high. In this simple scenario, overproduction can quickly lead to all other types of waste.

Causes of Overproduction

Overproduction can be caused by:

  • Poor demand forecasting
  • Unpredictable production schedules
  • Poor communication with line workers
  • Inefficient production machines
  • Unclear customer needs

The pull principle in lean manufacturing dictates that production should only be triggered by a demand for the product downstream. Therefore, no new product is processed or parts ordered unless the work in the downstream processes has gone past a specific threshold that signals the need for the next part.

Waiting

Waiting is seen as a waste because the company incurs certain expenses even when a person or machine is idle. However, waiting can also cause other forms of waste in manufacturing.

Scenario: There is a delay in delivering materials to the factory and some machines and workers have nothing to do until the material arrives.

Workers will still have to be paid for this unproductive time and machines may also be consuming energy while in standby mode.

Once the material arrives, workers may be pressured to work faster to ‘catch up’ or meet production targets. This frenzy can lead to more defects. The workers may also have to work overtime and this will raise the labor costs for the day. If the company can’t deliver on time, they will have dissatisfied customers.

Causes of Waiting

Waiting can typically be caused by:

  • Machine breakdowns
  • Long setup times
  • Poor communication between managers and workers
  • Poor process control
  • Poor supplier and distributor relationships

Lean manufacturing tools such as TPM reduce unplanned stoppages in production. Establishing flow and a pull system means setting up robust supply and distribution networks and having a good plant layout to limit unnecessary delays at any stage in a process. Value stream mapping also leads to efficient processes with a smooth flow of materials and information.

Motion

Unnecessary motion increases the time it takes to get work done and consequently, the cost of work. However, it does not increase the product value and is thus, waste.

Unnecessary motion can include physical movements by workers, i.e., lifting, reaching, and bending. It can also mean unnecessary movement by a machine.

Scenario: Worker looking for tools needed for a value-adding activity

The worker will spend time locating tools, especially if there is a poor organization system in their workspace. This increases production time for the part. The excessive movement can also lead to injury which will create additional costs.

Causes of Motion Waste

Motion waste can be the result of:

  • Inefficient workstation layout
  • Poor process planning
  • Shared tools and equipment
  • Lack of storage resources

Lean manufacturing tools such as 5S reduce motion waste by reducing the clutter which makes it harder to find items. 5S also introduces organizing systems that ensure tools can be quickly and ergonomically accessed.

Transportation

Transportation or material handling adds no value to parts but is often an unavoidable waste. However, it becomes a true waste when the transportation can be avoided.

Scenario: Workstations handling two subsequent processes are placed on opposite sides of the factory floor. 

In this situation, the parts from one process must be transported a long distance to the next process. Moving the parts longer distances increases production time and puts extra wear and tear on transport equipment. There is a higher risk of waiting at the next workstation and of defects caused by excessive handling during transportation.

Causes of Motion Waste

Motion waste can be caused by:

  • Poor plant layout
  • Poor process design
  • Large inventories
  • Inefficient location of storage facilities

Lean manufacturing improves the value stream by removing unnecessary steps, planning processes better, and improving plant layouts. All these limit the amount of transportation needed. The flow principle also eliminates physical barriers that must be navigated around.

Overprocessing

Overprocessing waste is when steps or features that don’t add value the customer is willing to pay for are added. Overprocessing increases the cost of producing items, commits resources that could have been used elsewhere, and can lead to customer dissatisfaction.

Scenario: Unnecessary Smartphone Features

When unnecessary features that customers won’t use are added to smartphones, they become more expensive. Adding these features increases production times and can contribute to more defective products. Additionally, customers may be unwilling to pay extra for the value of the unnecessary features resulting in poor sales.

Causes of Overprocessing

Overprocessing can be caused by:

  • Poor understanding of customers’ needs
  • Slow approval processes
  • Poor communication

Lean manufacturing avoids overprocessing through value stream mapping. This process identifies and eliminates processes that don’t add value to the product. Lean manufacturing’s main principle is also identifying value from the customer’s perspective. This ensures there is a better understanding of what customers need from a product.

Inventory

Inventory waste implies having more stock than is necessary to meet the present demand. This includes excess raw materials, finished goods, and work in progress.

Holding excess inventory incurs many costs including storage fees, insurance, labor, and depreciation. It also ties up capital that could be put to more productive use. Excess inventory can also lead to transportation waste, waiting, and defects.

Scenario: The company orders excess materials

The company will need space to store the excess materials and they will have to be transported to and from storage. The material may also degrade while in storage or its value may drop due to market conditions. The situation can also cause defects through excessive handling or by creating downstream production pressures.

Causes of Excess Inventory

Excess inventory can be due to:

  • Overproduction
  • Poor demand prediction
  • Poor communication
  • Production delays

The flow principle of lean manufacturing ensures there is less waiting that can lead to the accumulation of inventory. The pull principle ensures that new materials and parts are only ordered when there is a demand downstream. This also limits overproduction.

Defects

Defects are parts that must be reworked or disposed of because they don’t meet the standards demanded by the customer. When there are defects, additional resources must be used to rework the part, increasing its production cost. Alternatively, the part has to be scrapped.

Defects represent wasted time, money, and other resources. They can also affect customer satisfaction.

Scenario: Imprecise cuts are made on a part by a poorly maintained cutting tool.

In this case, the affected part has to return to a previous process to be reworked. More time and resources must be committed to completing this work. Additionally, other parts will have to wait until the rework is done causing waiting waste. Moving the part back through the process causes transportation waste as well.

Causes of Defects

Excess inventory can be caused by:

  • Poor maintenance of production tools and equipment
  • Human error occasioned by production pressures and other issues
  • Poor process standards
  • Poor understanding of customer needs
  • Excessive handling
  • Poor quality control

Every step of lean manufacturing helps to prevent defects. With a good understanding of value, manufacturers know what standards their products must meet. Mapping the value stream will eliminate sources of production pressures and unnecessary steps that lead to excessive handling.

The flow principle helps to keep tools and equipment at their best and the pull principle limits overproduction and inventory waste which can contribute to defects. Finally, the perfection principle ensures there is a commitment to improve the production process in every aspect.

The 8th Waste: Unused Talent

This waste was added when the Toyota Production System was adapted to lean manufacturing. Unused talent refers to when the potential of a worker is underutilized in a work environment. This waste is typically a management issue. Examples of this include:

  • Employees being inadequately trained for a job
  • Employees being given the wrong or no tools
  • Employees not being challenged or being given opportunities to improve
  • Employees being tasked with the wrong responsibilities

If, for example, an employee is not trained to operate a production machine properly, they will work slowly or will produce parts with more errors. Common causes of unused talent include:

  • Poor management policies
  • Lack of training
  • Poor communication between workers and managers
  • Lack of employee engagement

Value stream mapping can help identify signs of unused talent such as long process times or bottlenecks in production. Establishing a good lean implementation strategy must also include proper training of workers on lean practices and their jobs.

Conclusion

Wasteful practices cost companies more money than they realize. By eliminating some of the waste from their manufacturing processes, companies can significantly boost their profits while giving customers more value.

Eliminating waste starts by understanding what waste is in the first place. Lean manufacturing does an excellent job of classifying different types of waste that may become normalized in companies but are easily avoidable.

An important lesson that lean manufacturing also teaches is that waste generates more waste. When one form of waste is not properly handled, it can easily have a snowball effect, trapping your company in a cycle of wasteful practices.

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