What are the seven wastes?
The seven wastes are categories of unproductive manufacturing practices identified by Taiichi Ohno, the father of the Toyota Production System (TPS). The categories are an integral part of the TPS (known as lean production in North America).
Following are the seven wastes, as categorized by Taiichi Ohno:
- Overproduction -- Manufacture of products in advance or in excess of demand wastes money, time and space.
- Waiting -- Processes are ineffective and time is wasted when one process waits to begin while another finishes. Instead, the flow of operations should be smooth and continuous. According to some estimates, as much as 99 percent of a product's time in manufacture is actually spent waiting.
- Transportation -- Moving a product between manufacturing processes adds no value, is expensive and can cause damage or product deterioration.
- Inappropriate processing -- Overly elaborate and expensive equipment is wasteful if simpler machinery would work as well.
- Excessive inventory wastes resources through costs of storage and maintenance.
- Unnecessary motion -- Resources are wasted when workers have to bend, reach or walk distances to do their jobs. Workplace ergonomics assessment should be conducted to design a more efficient environment.
- Defects -- Inspecting and quarantining inventory takes time and costs money.
Lean manufacturing is based on a just-in-time model of production to avoid the waste associated with overproduction, waiting and excess inventory.
Since the categories of waste were established, others have been proposed for addition, including:
- Underutilization of employee skills -- Although employees are typically hired for a specific skill set, they always bring other skills and insights to the workplace that should be acknowledged and utilized.
- Unsafe workplaces and environments -- Employee accidents and health issues as a result of unsafe working conditions waste resources.
- Lack of information or sharing of information -- Research and communication are essential to keep operations working to capacity.
- Equipment breakdown -- Poorly maintained equipment can result in damage and cost resources of both time and money.
Although the seven wastes list was created for manufacturing, the categories can be adapted to apply to most types of workplaces.
See also: lean programming.