Pull Signal
Is a pull signal the same as demand forecasting?
No. A pull signal is an execution trigger based on actual consumption or order release, whereas forecasting is a planning input used more heavily in push systems.
What metrics determine whether a pull signal is working correctly?
Inventory accuracy, replenishment lead time, signal-to-receipt cycle time, stockout frequency, and adherence to standard container or kanban quantities.
What fails first in an electronic pull system?
Data integrity usually fails before material flow: inaccurate transaction timing, stale master data, or unposted moves cause the system to believe inventory exists or is consumed when reality is different.
A pull signal is a demand-trigger used in inventory and production control to authorize replenishment only after downstream consumption, customer order, or a preset inventory threshold occurs. In lean manufacturing, the signal can be physical or digital—most commonly a kanban card, scan, or system event—that tells the upstream process exactly what quantity to replenish and when. It replaces forecast-driven push logic with consumption-driven ordering.
On a manufacturing shop floor, a pull signal fires when a line-side bin empties, a kanban card is removed, or a barcode/RFID scan records consumption at the point of use; that event immediately releases a replenishment action to the upstream process or supermarket. In warehousing, withdrawal kanbans or system triggers create a replenishment order for a specific SKU or location, restoring inventory only to its defined target level rather than relying on forecast. For raw material tracking, the signal propagates upstream from finished-goods consumption to subassemblies and raw materials, forming a controlled chain tied to actual usage. This synchronization reduces excess inventory and dampens the bullwhip effect. The trigger point acts as a decoupling point where inventory policy shifts from push to pull. Success demands accurate on-hand balances, stable lead times, disciplined scan compliance, and defined container sizes; otherwise the signal loses reliability and true pull behavior breaks down.
Signal loss from skipped scans: If empty-bin scan, kanban return, or withdrawal transaction is missed, upstream process never gets replenishment cue, causing line starvation, delayed kit builds, and stockouts.
Phantom replenishment from bad inventory accuracy: On-hand counts at supermarket or point of use are wrong, signal fires too early or too late, causing overproduction or emergency expediting from incorrect consumption data.
Lead time instability and bottlenecked receiving: If suppliers, receiving, inspection, or put-away cannot replenish in designed cycle time, downstream consumes faster, safety stock depletes, and work-in-process stalls.