Just-In-Time (JIT)

JIT is built on several interconnected principles. First is demand-pull production: nothing is manufactured until a customer order or downstream kanban signal triggers it. This eliminates the overproduction waste that is the single largest source of inefficiency in most factories. Second is continuous flow, where production steps are arranged to minimize waiting and transport between operations. Third is takt time alignment, ensuring that production pace matches customer demand rate so that neither overproduction nor underproduction occurs. Fourth is zero defects, because without buffer stock, any quality issue immediately halts the line — making robust quality at the source (jidoka) essential. Fifth is supplier synchronization, where key suppliers deliver small, frequent shipments directly to the production line rather than to a central warehouse. Together, these principles create a tightly coupled system that is highly efficient under stable conditions. The trade-off is that JIT systems are more vulnerable to supply chain disruptions, making risk management and supplier diversification critical considerations.

Transitioning to JIT is a phased journey, not an overnight switch. Start by mapping your value stream to identify where the largest inventory buffers exist and why. Often, excessive inventory masks underlying problems — unreliable machines, inconsistent suppliers, or long changeover times. Address these root causes first using tools like Total Productive Maintenance (TPM) for equipment reliability, SMED (Single-Minute Exchange of Die) for faster changeovers, and supplier development programs for delivery consistency. Next, implement a pull system — kanban is the most common mechanism — for your highest-volume components. Reduce batch sizes gradually, monitoring the impact on delivery performance at each step. Use a production scheduling tool to plan at the shift level rather than the weekly level, providing the granularity JIT requires. Establish clear escalation protocols for supply disruptions, including pre-negotiated expedite agreements with backup suppliers. Measure progress with metrics like inventory turns, days of supply on hand, and dock-to-dock time.

Effective JIT scheduling requires real-time visibility into demand, production status, and supplier delivery timelines. Traditional spreadsheet-based scheduling lacks the responsiveness JIT demands — by the time a spreadsheet is updated, the information is already stale. Modern production scheduling platforms like LinePlanner provide a shared, real-time view of the production calendar that updates as orders are received, tasks are completed, and delays occur. Drag-and-drop scheduling makes it easy to resequence production in response to priority changes. Color-coded status indicators highlight at a glance which orders are on track, at risk, or late. Integration with supplier portals can trigger just-in-time material deliveries automatically. The shift-level scheduling granularity in LinePlanner is particularly valuable for JIT, because it allows planners to align material arrivals with the specific shift when they will be consumed — eliminating the staging time and floor space that coarser scheduling horizons require.