At a Glance
- Origin
- Toyota Production System (TPS), Japan, 1950s–60s
- Objective
- Zero stock, minimal tied-up capital
- Punctuality requirement
- 99 %+ (typically ±15 minutes)
- Extension
- JIS (just-in-sequence) for sequence accuracy
- Main risk
- Chain interruption with no buffer stock
The JIT concept: origins and basic principle
Just-in-time was developed by Toyota in the 1950s and 1960s as part of the Toyota Production System (TPS). The basic principle: no part is produced or delivered before it is needed. Production is driven by actual demand (the pull principle) rather than by forecasts and stock building (the push principle).
What functioning JIT logistics requires
JIT only works under strict conditions. First, suppliers must be extremely reliable – on-time rates of 99 % or more are required. Second, delivery windows must be agreed and met precisely (often to a 15-minute slot). Third, manufacturers and suppliers need closely coordinated IT systems.
The risks: when JIT fails
The COVID-19 pandemic made the vulnerability of JIT supply chains plain: a shortage of semiconductors brought car plants to a standstill worldwide because there was no stock to buffer it. Other risks include natural disasters, strikes and border closures. Many companies have responded with just-in-case buffers for critical components.
JIT vs just-in-sequence (JIS)
Just-in-sequence (JIS) extends JIT: parts are delivered not only at the right moment but also in exactly the right order for the production line. For example, at a car plant seats arrive in the exact colour and specification sequence in which the vehicles pass down the assembly line.
