Taiichi Ohno’s categorization of the seven major wastes typically found in mass production:
- Overproduction: Producing ahead of what’s actually needed by the next process or customer. The worst form of waste because it contributes to the other six.
- Waiting: Operators standing idle as machines cycle, equipment fails, needed parts fail to arrive, etc.
- Conveyance: Moving parts and products unnecessarily, such as from a processing step to a warehouse to a subsequent processing step when the second step instead could be located immediately adjacent to the first step.
- Processing: Performing unnecessary or incorrect processing, typically from poor tool or product design.
- Inventory: Having more than the minimum stocks necessary for a precisely controlled pull system.
- Motion: Operators making movements that are straining or unnecessary, such as looking for parts, tools, documents, etc.
- Correction: Inspection, rework, and scrap.