Just in Time Manufacturing
Just in Time manufacturing pulls parts and materials in only as the next process needs them, so inventory, waiting and overproduction get squeezed out of the line.
Materials are pulled through a line of stations, each one drawing only what the next step actually needs.
Reach for this when…
- Warehouses are full of stock that ties up cash and hides quality problems.
- Lead times are long because every stage batches up work before passing it on.
- A defect from three shifts ago is only found once it reaches the customer.
How to run it
- Pull from actual demand: nothing is made until the next step calls for it.
- Cut batch sizes and increase delivery frequency, even if each delivery costs more.
- Standardise the work so variation does not force safety stock.
- Stop the line the moment a defect appears, rather than let it pass downstream.
- Build supplier relationships tight enough to deliver small and often, reliably.
A worked example
Situation. Budi Santoso ran Suryamas Parts, an auto-parts plant in Surabaya, Indonesia, sitting on six weeks of stamped-metal inventory to cover supplier delays.
Applied. He moved the plant to pull scheduling, cut order batches to daily lots, and gave two key suppliers a standing slot on the line's kanban signal instead of a monthly forecast.
Result. Inventory fell from six weeks to four days, and a stamping defect that used to surface a month later was caught and fixed the same shift.
The catch
JIT removes the buffer that used to hide problems, so it exposes every weak supplier and every unstable process at once, which is the point but is genuinely painful the first year. It also leaves almost no slack for shocks: a single blocked port or a failed supplier can stop the line within days. It fits repeatable, high-volume production far better than volatile, custom, or low-volume work.
JIT without supplier reliability is not lean, it is fragile.
Origin: Taiichi Ohno; Toyota Production System