6 Warehouse functions and flows

“Success is a process, not an event.” — Richie Norton

Learning objectives

identify the main operations inside a warehouse;
explain how receiving, put away, storage, order picking, and shipping connect; and
distinguish optional activities such as pre-packaging, kitting, and cross-docking.

Typical warehouse functions and flows

Warehouses perform several everyday activities regardless of size or industry. The terminology may change, but the tasks remain remarkably similar:

Receiving. Accepting and inspecting inbound shipments.
Put away. Moving goods from receiving to their designated storage location.
Storage. Physically containing goods until they are needed.
Order picking. Retrieving goods from storage to satisfy customer orders.
Shipping. Consolidating, packing, and loading orders for dispatch.

The classical linear view of a warehouse process emphasizes the sequential nature of these main activities. In this simplified model, goods flow from receiving to put away, then into storage, out through order picking, and finally to shipping (see Figure 6.2 and Figure 6.1).

%%{init: {"themeVariables": {"fontFamily": "Arial, sans-serif"}}}%%
flowchart LR
  R["Receiving"] --> P["Put away"]
  P --> S["Storage"]
  S --> O["Order picking"]
  O --> SH["Shipping"]

Figure 6.1: Traditional Warehouse Process Flow.

Terminology

Terminology varies across industries. Some authors refer to functions, others to internal activities or operations, but they all describe the same underlying processes.

Extended warehouse functions and flows

Figure 6.2 shows the main internal warehouse flows and their connections. Products from suppliers enter through Receiving, where they are inspected and processed. From there, goods can be routed to reserve storage for bulk inventory, primary picking areas for faster access, or directly to Shipping through cross-docking for immediate dispatch. Customer returns use the same entry point before inspection and routing. Replenishment processes maintain the connection between reserve storage and case picking areas, while broken case picking areas supply items to Accumulation, Sortation, and Packing, ensuring orders are consolidated and prepared efficiently before reaching Shipping.

%%{init: {"themeVariables": {"fontFamily": "Arial, sans-serif"}}}%%
flowchart TB
  S["Suppliers"] == "Products" ==> R(["Receiving"])
  C2(("Customers")) == "Returned<br>products" ==> R
  subgraph Warehouse["Warehouse"]
    direction TB
    R -- "Direct put away<br/>to reserve" --> RS(["Reserve storage and<br/>pallet picking"])
    R -- "Direct put away<br/>to primary" --> CP
    R -- "Cross docking" --> SH
    RS -- "Replenishment" --> CP(["Case<br>picking"])
    CP -- "Replenishment" --> BCP(["Broken-case<br>picking"])
    CP --> ASP(["Accumulation,<br/>sortation,<br/>and packing"])
    BCP --> ASP
    ASP --> SH(["Shipping"])
  end
  SH ==> C(("Customers"))

Figure 6.2: Comprehensive overview of warehouse functions and flows, highlighting Receiving, Storage, Picking, and Shipping processes.

Receiving

Receiving controls which goods enter the warehouse records and storage system. Workers unload trucks, compare incoming goods with purchase orders and quality requirements, and record accepted units in the warehouse management system (WMS). Receipt errors then affect inventory records and downstream work:

Unload and check: Workers unload pallets or cartons, count items, and compare them with the supplier’s packing list and purchase order. This step verifies quantities and item identifiers (SKUs).
Inspect quality: As items are counted, they are inspected for damage or defects. Early detection allows issues to be addressed before goods enter inventory.
Record receipt: Accepted items are logged into the WMS using barcode or RFID scanners; this updates stock levels in real time and generates labels or reports. Accurate data capture prevents future stock discrepancies.
Stage for put away: Goods are temporarily placed in a staging area and labeled so that put-away staff know where to store them.

Receiving checklists and electronic advanced shipment notices can reduce processing time and errors. Receiving also gives staff the first opportunity to identify overages, shortages, and damage (OS&D), file claims, and reconcile physical goods with system records.

Cross-docking

Sometimes, goods do not need to be stored at all. In cross-docking, inbound shipments are immediately sorted, packed, and loaded onto outbound trucks for customers. This technique is used when fulfilling back orders or handling high-velocity items, reducing handling and storage costs. Successful cross-docking requires precise scheduling and real-time information so that inbound and outbound flows are synchronized.

Pre-packaging and kitting

Warehouses may process incoming goods before storage. In pre-packaging (also called pre-pack), workers prepare fixed kits, bundles, or retail-ready packages before receiving a customer order. Promotional bundles, subscription boxes, and retail distribution use this process when orders repeatedly contain the same SKUs. Pre-packaging reduces work near dispatch and requires accurate demand forecasts and inventory plans.

Kitting combines individual items into a ready-to-ship unit. For example, a warehouse can register a yoga mat, resistance band, and water bottle as one “fitness kit” line item. E-commerce, healthcare, and manufacturing operations use kitting to reduce repeated handling and picking errors. Both pre-packaging and kitting transform receiving into a value-added service, but they require space and labor. When storage volume or product variety makes pre-packaging impractical, warehouses may store items in bulk and package them only when demand materializes.

Put away

Put away moves goods from receiving to an assigned storage location. The location decision affects space use, labor, and inventory accuracy. The process has 5 basic steps:

Select product to put away: Pickers retrieve pallets or carts from the staging area.
Identify and scan: Using RF or barcode scanners, they identify the job and the specific SKU to be put away.
Travel to location: The WMS directs them to a designated slot based on criteria such as item size, weight, turnover rate, or family.
Place and record: Goods are placed into the assigned location, and the location’s barcode is scanned to confirm.
Repeat until complete: The process continues until all items in the pallet or cart have been stored. A variety of put-away strategies exist. For example:`

Directed or slotted put-away relies on rules or real-time data to guide storage decisions (e.g., placing heavy items on lower racks, fast-moving SKUs near the front, and slow movers in more remote locations).
Random or chaotic storage assigns goods to any available slot. The WMS must then maintain accurate location records.

Put-away decisions depend on product weight, dimensions, fragility, stackability, transaction volume, received quantity, value, and picking method. Automated storage and retrieval systems (AS/RS) and conveyors can reduce manual travel and placement errors.

Storage

After put away, goods remain in storage until demand arises. Storage design balances accessibility, space use, and product care. The method depends on item size, quantity, handling characteristics, containers, and environmental requirements.

Pallet storage systems accommodate bulk or palletized loads and often use high bay racking or automated pallet shuttle systems.
Case storage systems store products in cartons or cases on shelving or flow racks, often with a forward picking location where small quantities of frequently picked items are staged.
Broken case (each) storage systems store individual units in bins, drawers, or carousel systems for piece picking. These areas often feature ergonomic workstations and pick-to-light or voice-directed technologies.

Storage policy and material-handling choices affect space use, handling cost, and product condition. Temperature-controlled warehouses may separate dry, cold, and ambient zones. Forward pick locations place fast-moving SKUs near picking areas to reduce travel time.

Order picking

Order picking is the process of removing items from storage to meet a specific demand. It is the basic service a warehouse provides for its customers and the function around which most warehouse designs are based. Accurate and efficient picking underpins customer satisfaction and profitability because picking errors are expensive to fix once orders leave the warehouse.

Different picking strategies exist, and the optimal method depends on order profiles and warehouse layout:

Single-order (discrete) picking: A picker gathers one order at a time. The method requires little coordination and can create excessive travel at high volumes.
Batch (multi-order) picking: Several orders with similar items are picked together to reduce travel time.
Zone picking: The warehouse is divided into zones; pickers work in one zone, and orders move from zone to zone until complete.
Wave or cluster picking: Orders are released in waves based on shipping schedules or carrier cut-off times; cluster picking uses multiple totes to pick items for multiple orders simultaneously.

Pick-to-light, voice-directed picking, and automated picking systems can reduce search time and picking errors. Routing rules and real-time WMS guidance direct pickers through the warehouse.

Shipping

The shipping process transforms picked items into customer shipments. It includes multiple steps:

Sort and accumulate: Batch picks are sorted into individual orders, and distributed picks are accumulated into orders when multiple items are required.
Check for completeness and accuracy: This is the last opportunity to verify that orders contain the correct items and quantities.
Package goods: items are packaged in appropriate containers (polybag, box, pallet, etc.), using protective materials as needed. Packing methods may be manual or automated; automated packing systems use carton erectors, auto baggers, and document inserters to speed the process.
Prepare documents: Shipping labels, packing lists, and bills of lading are generated and attached to the packages.
Weigh and cube shipments: Orders may be weighed and measured to determine shipping charges.
Accumulate by carrier and load: orders are consolidated by outbound carrier, staged at the dock, and loaded onto trucks.

Efficient packing and shipping protect goods during transit, reduce the risk of damage and returns, and ensure that customers receive their orders on time. Many warehouses invest in transportation management systems (TMS) and route optimization software to schedule pickups and select the best carriers. High-volume operations use automation to reduce manual labor and maintain throughput, especially under tight delivery schedules.

Conclusion

Warehousing combines interdependent processes that move goods accurately and within the required time:

Receiving verifies quantities and quality, updates the WMS, and stages goods for put away.
Put away assigns each item to an optimal location based on its characteristics and expected demand; WMS guided strategies and automation improve accuracy.
Storage balances space utilization with accessibility; pallet, case, and broken case systems cater to different unit loads while forward pick locations speed picking.
Order picking retrieves items to meet customer demand; the picking method and supporting technology affect travel time and errors.
Shipping consolidates, packs, and dispatches orders, ensuring that goods are protected, documents are accurate, and carriers are properly scheduled.

Optional activities such as cross-docking, pre-packaging, and kitting change where handling occurs. Cross-docking bypasses storage for selected items. Pre-packaging and kitting assemble items before order release to reduce downstream work.