The supply chain in brief
A supply chain is the path goods take from raw materials to a finished product in a customer’s hands: suppliers, manufacturers, warehouses, transport and stores. Supply chain management is the coordination of that path. Because goods and information move at the same time, IT has a central role. A shipment is only as useful as the information that says what is in it, where it is and when it will arrive.
This article focuses on inventory control, the part of the chain concerned with how much stock is held and where.
Why inventory control matters
Holding too little stock risks running out, lost sales and unhappy customers. Holding too much ties up money, uses storage space and, for some goods, leads to spoilage or obsolescence. Inventory control tries to balance these. Software helps by keeping a current record of stock and by providing the information to decide what to order and when.
What an inventory system records
At its core, an inventory system keeps a record for each item, often called an SKU (stock keeping unit), and a quantity for each location. Whenever stock moves, the record changes. Typical events are:
- Receiving. Goods arrive from a supplier and quantities increase.
- Put-away. Goods are placed in a specific storage location.
- Picking. Items are taken to fill a customer order and quantities decrease.
- Shipping. Orders leave and are linked to a carrier and tracking number.
- Returns and adjustments. Returned goods, damage or counting corrections are recorded.
A record of each movement creates a history, which helps trace errors. If the system shows 40 units but the shelf holds 38, the history may show where the difference arose.
Capturing data accurately
Software is only as accurate as the data entered into it. Manual typing leads to mistakes, so warehouses commonly use technology to capture movements automatically.
- Barcodes and handheld scanners identify items and locations quickly.
- QR codes hold more information in a small space.
- RFID tags can be read without direct line of sight, so a pallet may be read as it passes a gate. These tags cost more and can be affected by metal and liquids.
- Sensors and connected devices, including those described under Internet of Things, can report conditions such as temperature for goods that need cooling.
Each of these produces a stream of data that must reach the central system reliably, which depends on dependable Wi-Fi coverage in large warehouses and on sensible handling of lost connections.
Counting and reconciling stock
Records drift from reality because of theft, damage, picking errors or unrecorded moves, so physical counts are needed. Two common approaches are:
- Full stocktake. Everything is counted at once, often at year end, which can mean pausing operations.
- Cycle counting. A few items or locations are counted regularly, so the whole warehouse is covered over a period without stopping work.
Differences between the system and the shelf are investigated and then corrected with a recorded adjustment, so there is an audit trail.
Reorder points and safety stock
Many systems help decide when to reorder. A simple method is the reorder point. It is the stock level at which a new order should be placed, so that new stock arrives before the old runs out.
A basic formula is: reorder point equals average daily demand multiplied by lead time in days, plus safety stock. Lead time is how long a supplier takes to deliver. Safety stock is an extra buffer for variation.
Here is a hypothetical example. Suppose an item sells about 20 units per day on average, the supplier takes 7 days to deliver, and the business keeps a buffer of 40 units. Demand during the lead time is 20 times 7, which is 140 units. Adding the buffer gives a reorder point of 180 units. When stock falls to 180, the system suggests placing an order. These numbers are only for illustration; real demand varies, and choosing a buffer involves judgment about the cost of running out versus the cost of holding extra.
More advanced planning uses forecasts based on past sales, seasons and promotions. Forecasting methods, including statistical modeling and sometimes machine learning, can help, but forecasts are uncertain and are best treated as estimates to be reviewed by people who know the market.
Connecting the systems
Inventory control rarely stands alone. Related systems include:
- Order management, which takes customer orders and reserves stock
- Warehouse management systems, which direct picking and put-away
- Transport management, which plans shipments and tracks carriers
- Purchasing, which sends orders to suppliers
- Financial management systems, which value the stock and record costs
Online shops add another link: the website should show accurate availability, or customers will order items that are not there. Connections between these systems are usually built with APIs or scheduled data transfers, so monitoring is needed to catch failed or duplicated messages.
Visibility and reporting
Managers use dashboards to see stock levels, slow-moving items, late deliveries and order fulfillment rates. Good reports depend on clean, consistent item data. Duplicated or inconsistently named items are a common cause of confusion and are the kind of problem data cleaning is meant to fix.
Risks and resilience
If the inventory system goes down, picking and shipping can stop. Warehouses therefore plan for outages with backups, offline modes on scanners and a clear business continuity approach. Supplier data and shipping information also cross organizational boundaries, so access should be limited to what partners need and accounts reviewed regularly. Supply chains can be disrupted by events outside anyone’s control, so technology improves visibility but cannot remove uncertainty.
Practical advice
- Keep item and location codes simple and consistent.
- Record every movement at the time it happens.
- Count regularly and investigate differences instead of just correcting them.
- Review reorder settings periodically, as demand changes.
- Test any system change with the people who work on the warehouse floor.
Inventory control is about having the right goods in the right place at a sensible cost, and IT is what makes the necessary information available quickly enough to act on.