Kanban

Kanban comes from the Toyota Production System and is the operational tool of just‑in‑time. A typical loop connects a line‑side rack with a supermarket or a supplier: when a container is emptied, its card goes back upstream and triggers replenishment of exactly one container. Electronic kanban (e‑kanban) replaces physical cards with scans, but the logic stays the same. The basic sizing formula is:

• Number of cards = daily demand × replenishment lead time (days) × (1 + safety factor) ÷ container quantity

Kanban in practice

The card count is a parameter, not a constant. A line uses 400 units a day, a container holds 50 units, replenishment takes half a day and the safety factor is 20%: 400 × 0.5 × 1.2 ÷ 50 = 4.8, so the loop gets 5 cards. If the cards are collected from the line only every half day, the waiting time is part of the lead time too. Lead time grows to one day and the same loop needs 10 cards, without any change on the supplier side.

The second source of drift is demand. When a new product ramps up and consumption rises to 600 units a day, the loop needs 8 cards; with the original 5 it holds at most 250 units while the line uses 300 during a single replenishment cycle, and it runs dry. When demand drops to 250 units, 3 cards are enough and two full containers sit idle. Kanban works best for repetitive parts with fairly level consumption; for low‑volume, high‑variety items or volatile demand, planning from MRP tends to be the better fit.

Logio designs kanban loops, supermarkets and line feeding as part of intralogistics and material flow projects and tests card counts with dynamic simulation before they change on the shop floor. The demand figure behind the formula can come from Veritico STOCK, which forecasts demand per item, location and day.

Related terms

• Just‑in‑Time (JIT)
• Lean Manufacturing
• Material Requirements Planning (MRP)
• Lead Time
• Bill of Materials (BOM)