Lean manufacturing has broken through the plant-floor ceiling. While lean principles have long been deployed at a grassroots level, the benefits are only now fully recognized by others in the organization.
There are many views of lean manufacturing. To purists, lean is the Toyota Production System (TPS), based on level-loading production replenishment to support pacemaker operations. To some, it's kanban replenishment to reduce inventories. To many, it's repetitive scheduling and pull-based kanban replenishment. To others, it's flow manufacturing, based on Demand Flow technology (developed by JCIT International) recently acquired by PeopleSoft Inc. And there are those that apply Drum-Buffer-Rope (from Eliyahu Goldratt's Theory of Constraints [TOC], used independently or as logic for some finite scheduling), other finite scheduling and advanced planning & scheduling (APS) to lean manufacturing initiatives.
Which is right? Most manufacturers will use whichever is best for their situation. Generally it depends on whether a product is standard or configured and made repetitively or infrequently. For standard products, a good choice is automated TPS-or lean management. For repetitive production, many have success with repetitive scheduling. For configured or small-quantity production, level-loading multiple operations using Drum-Buffer-Rope or flow manufacturing works well, and many also have success with finite scheduling or APS. Furthermore, most companies use a combination of approaches, including materials requirements planning (MRP) for other product lines and procurement.
In current lean initiatives, manufacturers want automated, synchronized and real-time capabilities that can link those initiatives across the organization and with trading partners.
Five years ago, lean solutions were based on Demand Flow principles. Today they are based more on the TPS lean precepts. TPS level schedules the replenishment rate to the pacemaker operation, while flow level loads an entire cell or focused factory. Both approaches assume flexible capacity resources and are designed to stabilize production by leveling demand over a given period. This reduces the bullwhip effect on inventory levels from demand variability on operations and suppliers. While some companies build to daily demand rates or one-piece flow rates for low-volume items, most have weekly or even longer periods for high-volume demand.
The core elements of a lean system are production leveling and kanban management-integrated into financials, procurement, ERP, demand planning, quality management and warehousing. A growing number of solutions also include value stream mapping, line design, lean analytics, method sheets and throughput costing.
What separates one solution from another is its approach to production leveling. To be a lean demand-driven enterprise, companies must integrate the performance improvements from their plants into the fabric of the organization. There are now many good solutions in the market to support the drive to be lean.