Lean Manufacturing and Just-In-Time Philosophy

Basic Idea Try to eliminate the system operational inefficiencies and the resulting waste by trying to produce the right items in the right quantities and quality at the right time through the right procedures. In the emerging philosophy, inventories should be carefully controlled and they should not function as the mechanism for accommodating the system inefficiencies => Just-In-Time (JIT) The aforementioned effort should an ongoing process towards continuous improvement rather than one-time/shot effort.

Enabling factors and practices of the lean manufacturing philosophy Reduce the variability in the system input quality of raw material delivery times operation processing times process capability (smaller) lot sizes output production volume production scope

Enabling factors and practices of the lean manufacturing philosophy (cont.) Timely and reliable information flow across the entire supply chain through stable, long-lasting and trustful relationships between the different parties in the supply chain flexible / electronic ordering mechanisms: Electronic Data Interchange (EDI), and e-commerce practices vendor owned and managed inventories

Enabling factors and practices of the lean manufacturing philosophy (cont.) Reliable and flexible production and transport systems establishment of well-tuned processes with predictable and controllable performance => Statistical Process Control (SPC) reduction of set-up times through the adoption of flexible equipment standardization of designs and production methods externalization of set-up tasks introduction of mistake-proofing techniques like explicit checklists integrated machine gages real-time linkage of the transport carriers to the corporate headquarters / operational planning center through mobile telephony and global positioning systems

Enabling factors and practices of the lean manufacturing philosophy (cont.) Well-trained, responsive and responsible / empowered personnel knowledge management quality circles employee ownership of the processes and their results flattened (middle) management structures

Push versus Pull production control schemes Push (MRP-type) control schemes: Predict the demand and try to initiate and coordinate production in order to meet these predictions under the available production capacity. Pull control schemes: Assuming a stable demand rate, establish the production capacity and the Work-In-Process (WIP) levels that will allow the system to meet demand as it occurs. Generated demand consumes the existing WIP’s and authorizes new (replacing) production, through a card-based mechanism known as KANBAN. Appropriate mainly for repetitive manufacturing environments.

KANBAN-based Production Systems + Station i Station i+1 A material balance equation: (Number of Kanbans) * (Container Size) = (Demand at Station i+1 over a Cycle Period) + (Safety Stock)