- Category: Lean
- Published: Friday, 11 March 2011 16:44
- Written by Stephen Booth
- Hits: 3798
Lean recognises 7 types of waste.
- Waiting - The periods of inactivity in a downstream process that occur because an upstream activity does not deliver on time. Idle downstream resources are then often used in activities that either don’t add value or result in overproduction. This is often the result of push based processes rather than pull. In non-manufacturing environments and tasks this can be the literal waiting of people when a meeting is delayed in starting because a key or senior attendee is late, time lost when a person delays responding to an email or voicemail or time lost when a person has to locate the person they need to speak to.
- Motion - Extra steps taken by employees and equipment to accommodate inefficient process layout, defects, reprocessing, overproduction or excess inventory. Motion takes time and adds no value to the product or service. “To move and add value is called work. To move and not add value is called motion. Motion, then, means moving without working, moving and adding cost”.
- Transport - This is unnecessary motion or movement of materials, such as work-in-process (WIP) being transported from one operation to another. Whilst some transport may be inevitable it should be minimized for two reasons; 1) It adds time to the process during which no value-added activity is being performed. 2) Handling damage could be incurred. Workstations should be as close as possible to the ones that immediately precede and succeed them, raw materials and parts should be as close as possible to the workstations that use them.
- Extra Processing - Extra operations, such as rework, reprocessing, handling, storage or management that occurs because of defects, overproduction or excess inventory.
- Inventory - Excess stock that is not directly required to fulfill current Customer orders. Inventory includes raw materials, work-in-process and finished goods. Inventory also requires additional handling and space.
- Defects - These are products or services that do not conform to the specification or Customer’s expectation, thus causing Customer dissatisfaction.
- Overproduction/Overwork - When operations continue to produce after demand has been satisfied. The results of overproduction are; Products being produced in excess of what’s required. Products being made too early. Excess inventory carrying costs
Recently some training and consultancy vendors have added an 8th form of waste, 'Un-utilised People'. This is differentiated from 'Waiting' (staff idle and not working) by concentrating on their skill sets. A person might be fully utilised in terms of time and may be generating value but if they were enabled and supported to use their full skill set or a different part of their skill set then they could generate more value in the same time period.