Just In Time
Just-In-Time (JIT) is a production and supply-chain philosophy that releases material, parts, and work only when needed, in exact quantities, matching actual demand rather than forecasts. In CNC machining, JIT means jobs are pulled by downstream demand, with machining and delivery timed to minimize waiting, work-in-progress, and finished-goods inventory. It is a management philosophy reducing waste in time, space, and resources.
In a real CNC or millwork shop, JIT shifts the production model from stocking large batches to making exactly what the next process consumes. A JIT cell uses Kanban signals to release work only when downstream operations use up the previous parts, so raw material is staged only for near-term jobs. For example, in edgebanding, panel cutting, edge application, and hardware kitting are sequenced so cabinets flow to assembly in the correct order without piling up in storage. This reduces handling damage, re-picking, and floor congestion. However, JIT only works if suppliers deliver reliably, setups are quick, and processes are stable because the low inventory leaves no room for delays or errors. The technical benefit is synchronized flow that cuts lead times and carrying costs, but every disruption becomes immediately visible.
Is JIT the same as lean manufacturing?
They overlap, but JIT is the demand-pull production method, while lean is the broader waste-reduction philosophy; some sources treat them nearly synonymously, but JIT is specifically about timing, quantity, and flow.
What is the core control mechanism in JIT?
The core control mechanism is a pull signal—often Kanban—that authorizes upstream production only when downstream consumption creates a need.
Why does JIT fail in real shops?
It fails when the shop cannot maintain supplier reliability, stable cycle times, short setups, and consistent quality, because JIT removes the inventory buffer that normally masks those problems.