5 Conclusion
As we see in the simulation, designing production systems that are as close as possible to one-piece flow will considerably reduce the amount of WIP inventories. As a direct consequence, organizations can reduce WIP inventories and waiting times (lead time), two of Lean’s seven main waste categories (remember TIMWOOD). Because less inventory will expose the process issues, companies will have stronger incentives to fix their root causes, which results in fewer defective parts. Manufacturing in smaller quantities rather than big batches also helps companies with overproduction waste by aiming for the ideal situation where it only produces as many as the customers need and only when they need them. Achieving one-piece flow may not have any noticeable impact on motion and overprocessing waste categories. However, unless countermeasures are taken (such as installing conveyor belts), one-piece flow might create extra transportation waste, as it requires more effort to move items one by one as opposed to moving them in batches.
How One-Piece Flow Impacts the Seven Waste Categories
| Waste category | One-piece flow production system |
|---|---|
| Transportation | can create extra transportation waste unless measures taken |
| Inventory | reduces WIP inventory |
| Motion | may not have any noticeable impact on motion |
| Waiting | reduces wait time |
| Overprocessing | may not have any noticeable impact on overprocessing |
| Overproduction | produces smaller quantities, therefore avoiding overproduction |
| Defects | has less inventory, therefore increasing the incentive to fix problems and decreasing the potential for defects |
