Process Flow Diagram
Is a Process Flow Diagram the same as a Data Flow Diagram?
No. A PFD emphasizes the operational sequence and control steps, while a DFD emphasizes the movement of data between entities and processes.
Why is FIFO sometimes written into the diagram?
FIFO is embedded in the storage or picking step to ensure older lots are issued first, reducing expiry, obsolescence, and lot-traceability errors.
Where does GRN creation fit in the receiving flow?
GRN belongs after receipt and inspection, before stock is formally updated and before invoice matching or payment processing.
A Process Flow Diagram (PFD) is a visual map of the sequence of process steps and decision points used to show how material, information, and approvals move through an operation. In manufacturing and supply chain contexts, it models receiving, inspection, storage, issue, replenishment, and shipment flows end to end. It links requisitions, purchase orders, goods receipt, quality checks, GRN, stock updates, binning, and material issue into a single control view.
In a real manufacturing setting, the PFD starts when stores raises a material requisition against a production order. That requisition becomes a purchase order, and when the shipment arrives, gate entry logs the truck, quality control inspects the goods, and the GRN is created only after the check passes. At that moment stock status changes from in-transit/received to inspected/available, and the ERP is updated before put-away assigns a bin location. FIFO is enforced during binning, and replenishment triggers automatically when stock falls below threshold. When production requests material, the PFD enforces issue authorization, deducts stock, and feeds the physical verification cycle. It also shows exception paths for damaged goods, missing quantities, or rework, so operators know whether to quarantine, return to vendor, or create a partial receipt.
Receiving bottlenecks: If gate entry, QC, and GRN creation are not clearly separated in the flow, trucks queue at receiving while paperwork waits for approval. This delays put-away and leaves stock appearing unavailable even though it is physically on site.
Stock-record mismatch: If the diagram does not enforce a stock update immediately after QC or issue, ERP shows available inventory that has already been consumed or quarantined. This causes production shortages, duplicate ordering, or missed customer commitments.
Missing exception paths: If the flow diagram only shows the happy path and omits shortages, damage, rework, return-to-vendor, or partial receipt branches, operators bypass controls and create unexplained variances between physical count, GRN, and ledger stock.