The Seven Forms of Waste
In this lesson, you’re expected to learn about the different types of waste in lean management.
• According to Toyota, producing more than is immediately needed by the next process is the greatest source of waste.
• Over-production can prevent other essential activities from taking place.
• Over-produced items end up as inventory or scrap, therefore creating more waste.
• Example: buying vegetables for one month on a weekly shopping trip.
• Waiting can often be avoided, as most machines do not need supervision.
• Essential waiting time can be filled productively (e.g. sub-assembly, quality checks, material handling etc.)
Improvement action:rebalance activities to remove waiting, then make essential waiting visible.
• It often results from a poor system design and/or layout.
• It can create handling damage and cause delays.
• Layout changes which bring processes closer together, improvements in transport methods, and workplace organization can all reduce waste.
Improvement action: minimize the transportation steps by gathering the work content using continuous flow processing.
• The process itself may be a source of waste. Some operations may exist only because of poor component design or poor maintenance and so could be eliminated.
• It may result from internal standards that do not reflect true customer requirements.
• It may be an undesirable effect of an operators’ pride in their work.
• It often arises when standards are difficult to define (e.g. polishing, finishing, and painting).
Improvement action: provide clear, customer-driven standards for every process.
• All inventory should become a target for elimination. However, it is only by tackling the causes of inventory that it can be reduced.
• It is often a symptom of other problems in the system that are hidden behind rising stock levels.
• It increases operational costs and manufacturing lead-time.
Improvement action: improve planning and commit to reduce unnecessary ’comfort stocks’.
• Rework is the consequence of failing at meeting the ‘do it right the first time’ expectation.
• It can be caused by inadequate methods, materials, machines, or manpower.
• It requires additional resources so that normal processes are not disrupted.
Improvement action: improve process capability by analyzing and resolving the root causes of rework.
• An operator may look busy but sometimes no value is being added by the work.
• Simplification of work is a rich source of reduction in the waste of motion.
• Manual and machine work cycles both often comprise unnecessary motion elements.
• Unnecessary motion can also be caused by a layout not being optimized for varying customer demands.
Improvement action: arrange tooling, equipment, and parts around workstations and use standardized procedures to minimize motion.