The 7+1 types of waste

5 lean principles

There are five lean principles which apply no matter in what kind of industry you are working.

  1. The first one is understanding what your customers value.
  2. If you know this you have to find out how and where in your process you create this value.
  3. In the next step, you have to make certain that your value flows throughout our process.
  4. In order to do this, you have to pull the value through your enterprise
  5. And finally, you have to pursue perfection

Value vs Waste

Now the lean community defines value as what the customer is prepared to pay for!  In other words, what isn't waste! Waste means that we spend resources such as time, space, material, money, energy,... on something the customer does not want to pay for. Therefore we need to know what the customer wants before we are able to start looking for waste.

In a production environment, you can define waste as everything which is not from the first time right and any activity where the product is not changing physically. If the product does chance we need to be certain that the customer is willing to pay for the change.

So we need to identify, classify and Finally  elimate  waste  in order to improve our process and have satisfied customers.  This waste is also called Muda in lean.

We have to be aware that if we start examining a process that we will see that only a small fraction of the time we are doing added value activities. This is why it is good to  start with mapping the waste in a proces and reducing it before we look to make the added value part more efficient.

Be aware that you will (probably) never be able to eliminate all the waste from your process. Some of the activities could be even obligated due to regulation.

Types of waste - TIM WOODS

Lets have a look at the Different types of waste that can be identified. You can easily remember them by using the acronym TIM WOODS:

  • Transportation
  • inventory
  • motion
  • Waiting
  • overproduction
  • over-processing
  • defects
  • Skills


Transport means that you are moving material around from one position to another. While moving the product, the product does not change meaning there is no added value. Forklifts driving around in a factory are a typical example of transportation. Transportation consumes time and space and often expensive equipment is needed.


Inventory are the materials stored away waiting to be consumed. these can be raw materials, semi-finished materials, or the end product. Again while stored the products are not physically changing meaning that there is no added value. Often these inventories are used as a precaution for when there will be unexpected demand or fast delivery is needed.

Inventory uses space that could be used for added value processes. Furthermore, do you increase the risk of high scrap and depreciation costs if customer demands are changing?


Motion are movements done by people and machine. Unnecessary motions consumes extra time and increase the wear of machines and risk of injuries.


Waiting means that there is no activity at all. It can be easily detected. The longer we wait the more time we waste.


When we produce more than the customer consumes we speak of overproduction. Overproduction is one of the worst wastes since it includes all the other wastes which took place during the production of the product.


Over-processing means that we are doing more than the customer needs. Adding extra features to our products that are not needed, performing process steps which are not required, using inappropriate production techniques, producing with the wrong equipment... can be all categorized under over-processing. Over-processing will consume extra resources that could be spent on real added value tasks. Using a CNC drilling machine for creating holes while a simple hand-hold drill would be sufficient is a good example of over-processing.


Defects occur when tasks have not been right from the first time. Because of this, we need to perform rework or even scrap the work already done when the defect is detected.  If the defect is not detected it will affect the quality of the product and will result in unhappy customers. Again this has an impact on the resources spent so far. Depending on your process you could even need to have an extra rework space.


The last waste is related to skills. On the one hand, letting somebody do a task who misses the right skills will result in a less efficient performance.  On the other hand, not using the complete skill set of your employees means that you are not using your resources efficiently. You could allocate these resources to other tasks in order to gain more added value.  Examples are employees who are poorly trained or do not have the right equipment to do the job. Or employees that are not challenged enough to come up with ideas to improve the process.

This article was updated on November 30, 2022