Lean thinking looks at this way of organizing production and sees a company producing a lot of work-in-process (WIP) inventory. The fastest equipment, such as stamping, will build up the most WIP. Material sitting in inventory is caused by the most fundamental waste, overproduction. The mass production system guarantees overproduction in large batches, which in turn guarantees inventory sitting idle and taking up valuable plant space and, more importantly, hiding problems.
