This waste is any supply in excess of a one-piece flow through the process, including work in process and finished goods. Holding inventory costs money - roughly 25 percent of the value of the inventory if held for a year. This is a major waste that includes material, labor, machine hours, inspecting, sorting or rework. Processing This waste is effort that adds no value from the customer's viewpoint. Expediting processing because of failing to meet schedule also is a waste.
Transportation Moving materials in the manufacturing process can add costs, but no value.
Not only does the act of transporting add to costs, it also typically involves using expensive equipment. Further costs are space, racking and the people and systems needed to track the material. Waiting for workers generally is of greater concern than machine use. Its symptoms include time looking for tools, extra product handling, walking and product arrangement, stacking, etc. Causes include poor plant layout and workplace design, inadequate training, weak processing and constant schedule changes to reduce on-time delivery problems.