Referring to the post from Markus Mink, (3-steps-to-identify-and-prevent-inefficiencies-in-companies-processes), I go elaborate on the seven types of waste.

How can we describe "waste"?

All activities and processes, although incur costs, but generate no value (for the customer).

For this purpose, seven types of waste have been identified:

1) Overproduction

Overproduction arises when a company produces more than the customer actually needs. This can include both, the production of products or components for which there are no current orders, as well as the production of more parts are needed than currently. Overproduction is the worst kind of waste because they usually multiply all the other species. It increases the reject and rework rate, the stocks, the throughput and wait times, and unnecessary movement and Transport.

2) Stocks

Stocks are mounted (provided) parts, which are required for the manufacture of a product. Of course, these parts also cause costs for a company. If the parts are not needed, they require valuable storage space, obsolete, where appropriate and consume upstream (raw) materials, which thus can not be used for the production of other more important products. Competitive companies thus so make sure that your system meets the stocks controlled so that no money is wasted for unneeded parts and subassemblies.

3) Errors (rework, scrap)

Rework is required when products and components are defective or damaged and therefore need to be repaired or reworked. Defects are caused by poor production processes, whether these are caused by human or mechanical error. Rework costs additional time and thus increases the cost of the actual final product. In the worst case arises defective goods.

4) Wait times

Every step of a manufacturing process is related to the processes of the upstream and downstream level. If employees, equipment, information or material delay the production process, time is wasted and the cost of production can be increased.

5) (Unnecessary) Transport

This includes unnecessary movement of information, products or components from one area to another. Unnecessary transports usually occur along with unnecessary motion, product damage, lost parts and systems that detect movements.

6) (Unnecessary) Movements

Unnecessary movements arise when employees move in the working environment and thereby require time and effort. Any kind of (unnecessary) movement is poorly standardized work, causes bad process design and bad (not ergonomic) design of workplaces.

7) Revision

Revision includes still needed (extra) steps in a production process. It may also involve the manufacturing of production, which have a higher quality than is needed. This can be caused by incorrectly used equipment, errors in rework, poor process design or poor communication. But often it is produced simply by the fact that is not checked exactly what the customer rather really needed.