Lean thinking defines the waste as Anything that uses resources, but does not add real value to the product or service.
Waste is classified into center categories:
● Defects: Instead of inspection, finding and repairing defects, they must be prevented from occurrence. Defects emerge from one or more of these items:
- Poor product design
- Misunderstanding of customer needs
- Lack of some skills and work instructions
- Unsatisfactory planned maintenance
- Low quality
- Shortages of process controls
● Waiting time: Down-stream (Next) activity is stopped and equipments are idle due to delay in delivery from an upstream (previous) activity. Causes of waiting time include:
- Lack of balance between processes namely engineering, workload, automation, scheduling, etc
- Long set up times
- Unplanned maintenance
- Lack of redundancy wherever possible
- Quality problems in upstream processes
● Over production (producing more, earlier or sooner than next workstation demand results in larger inventory and costs)
Causes of over production are:
- Just in case logic
- Lack of feedbacks from downstream processes
- Lack of balance between processes namely engineering, workload, automation, scheduling, etc.
● Transportation: This word refers to transportation within Work-In-Process (WIP) and occurs because of reasons like weak plant layout and shortage of understanding of production or process flow. It should be lowered as much as possible or even be eliminated e.g. by means of Work Cells because it adds no value to the product.
A Work Cell can be defined as: “Physical or logical arrangement of all resources (employees, machines, material) associated with the performance of an activity, job, or task.
● Inventory (Excess raw materials, finished products and WIP):
Although Inventory is a general term, but here it means type of inventory, which is not
required to meet customer needs directly. In addition, more space and handling is
needed. Inventory can be result of one of the following items:
- Poor communication
- Inadequate market forecasts
- Just in case logic
- Fluctuations in material procurement
- Poor scheduling
● Unused creativity (Failure in exploiting the knowledge and unique abilities of the employees):
Basis of unused creativity:
- Resistance to change
- Failure in employees’ involvement
- Low/no attention to training
● Over processing (Parts of processes that create no added-value to the product or service should be identified and eliminated)
This term may appear in forms of rework, excess inventory, reprocessing, etc. In other words, it is doing more than what the customer demands and is willing to pay for.
● Movement (Extra transportation due to wrong location of equipments and tools)
It can emerge due to one of the following causes:
- Low effectiveness of machines and employees
- Bad layout or unfavorable facilities
- Poor floor shop organization
