Just-in-Time

Origin. Toyota Production System; developed by Taiichi Ohno and Kiichiro Toyoda (1950s-1970s); JIT is one of the two pillars of TPS alongside Jidoka.

Mechanism. Produce only what is needed, when it is needed, in the amount needed. Eliminate inventory buffers that hide problems and consume capital. The system is pulled by customer demand, not pushed by production schedules. Lead times compress; quality problems surface immediately (no buffer to absorb defects); cash flow improves. JIT requires reliable processes: variability and unreliability cannot be buffered.

Procedure. Map the value stream from order to delivery. Identify inventory at each stage. For each buffer, ask: what problem does this inventory hide? Address the underlying problem (unreliable supply, quality issues, long changeovers). Reduce batch sizes and increase delivery frequency. Synchronize production to takt time. Pull from downstream; do not push from upstream. Stop the line when problems occur — JIT without Jidoka is chaos.

Applies to. Manufacturing, software deployment (continuous delivery), any system where inventory hides problems and delays feedback.

Limitations. JIT without reliability improvement is a recipe for stockouts and line stoppages. The approach assumes that underlying variability can be reduced; if it cannot (truly stochastic demand, unreliable suppliers with no alternatives), JIT amplifies volatility rather than absorbing it. Also: JIT optimizes a single supply chain; it pushes variability onto suppliers unless the system includes them.