Lean manufacturing is built upon the idea of eliminating wastes in business, muda, mura, and muri. Muda typically refers to 7 Wastes of Lean as identified by Taiichi Ohno, the father of the Toyota Production System. These are the seven most common wastes found in manufacturing, activities or processes that do not add value to the customer. Each of the wastes can lead to a slower production line, defective products, longer delivery times, dissatisfied customers, etc.
Since the conceptualization of the 7 Wastes and through the update to the 8 Wastes of Lean, overproduction has long been ranked as one of the worst, albeit overlooked, wastes in manufacturing. Simply put, overproduction is the result of producing more of a product than required by customer demand. This is common in batch-and-queue and mass manufacturing facilities and can include production happening before the customer demand actually requires it.
In a way, it can seem like manufacturing as many products as possible is ideal for that “just in case” scenario. However, this approach is likely to lead to whole host of issues. Overproduction is seen as one of the worst wastes of manufacturing not because it’s more wasteful or costly, but because it can easily lead to the other wastes of Lean including waiting, inventory, extra processing, and defects. Because overproduction results in high levels of inventory, problem-areas and quality issues can easily be hidden.
To eliminate the waste of overproduction, a facility must embrace the just-in-time production method. The JIT method utilizes a pull system instead of the push system that is at the core of mass and batch production. Instead of forecasting the customer’s demand, production is scheduled as requested. Typically used with a Kanban system, manufacturing of a product does not begin or continue until signaled. JIT is one of the central pillars of the Toyota Production System, the major precursor of Lean manufacturing.