Vendor Managed Inventory (VMI) is a replenishment model in which the supplier, not the customer, monitors an agreed set of stock items and refills them to pre-defined minimum and maximum levels. The customer shares consumption and stock-level data, and the vendor decides when and how much to ship. This shifts the buying decision upstream: instead of your team raising purchase orders, the supplier watches your usage and keeps the shelf full. VMI is common for high-volume production materials, packaging, fasteners, and maintenance (MRO) spare parts.
In a VMI arrangement, both sides agree on which items are covered and on a minimum and maximum quantity for each. The customer then feeds the supplier reliable data on current stock and recent consumption. The supplier reviews that data on a set cadence (daily, weekly, or continuously), compares it against the agreed thresholds, and generates a replenishment shipment whenever stock is heading toward the minimum. The typical loop looks like this:
The min and max are essentially a shared reorder point and target level. The minimum usually embeds a buffer of safety stock to cover demand and lead-time variability, so a spike in usage does not cause a stockout before the next shipment lands.
VMI lives or dies on data quality. The supplier can only replenish well if the numbers you send are accurate and timely. At minimum they need current on-hand stock, recent consumption or issue history, and any known upcoming demand changes. Poor data (missed goods receipts, uncounted issues, stale records) leads the supplier to ship too early, too late, or the wrong quantity. This is why a disciplined stock system matters: a CMMS that logs every spare part issued against a work order gives the supplier a clean, real-time consumption signal rather than a monthly guess.
VMI and consignment stock often travel together, but they answer different questions. VMI is about who decides replenishment (the supplier). Consignment is about who owns the stock (the supplier owns it until you consume it). You can run either one alone, or combine them:
Combining both minimises your working capital because you carry parts you have not yet paid for, while the supplier keeps them stocked.
Done well, VMI reduces two things at once: stockouts and administrative overhead. Because the supplier watches usage continuously and holds accountability for availability, the risk of running dry drops, which directly protects against unplanned downtime when a critical part is missing. Your buyers stop raising routine purchase orders for covered items, freeing them for higher-value sourcing. Suppliers gain visibility into real demand, so they can plan production and smooth their own inventory. Applying ABC analysis helps decide which items deserve VMI: high-turnover, high-consequence parts usually justify it, while slow-moving C items may not.
VMI is not free of risk. The biggest exposure is data quality: if your stock records drift, the supplier replenishes against fiction. The second is dependence. You hand replenishment control to one vendor, so a supplier failure or dispute hits harder. Mitigate this by keeping your own visibility of stock and usage (never go blind on data you have outsourced), auditing counts periodically, defining clear service levels and penalties in the contract, and retaining the ability to reorder manually if the arrangement breaks down. Ownership of the accurate usage data should always stay with you.
Maintenance, repair, and operations (MRO) spares are a natural fit for VMI: bearings, seals, filters, belts, and consumables that many machines burn through predictably. A VMI supplier can keep a bin stocked to agreed levels so maintenance never waits on a stores request. The catch is that MRO demand is lumpier than production demand, so the min and max must reflect real failure patterns rather than a flat average. Feeding the supplier issue data from every completed work order (which items were used, on which asset, how often) turns guesswork into a defensible replenishment plan. Fabrico tracks spare-parts consumption and stock levels as parts are issued against work orders, giving you and your VMI supplier the same accurate usage picture. To be clear, Fabrico is the data foundation: it does not place orders or auto-reorder for you, and the actual replenishment stays supplier-side under the VMI agreement.
Consider a hydraulic seal kit held under a VMI agreement.
First, set the minimum (the trigger). Expected demand during lead time is 8 kits/week multiplied by 1.5 weeks, which equals 12 kits. Add the 6-kit safety buffer: minimum equals 12 plus 6, so the trigger is 18 kits. Now suppose the current on-hand stock is 16 kits. Because 16 is below the 18-kit minimum, the supplier triggers a replenishment. The order quantity brings stock back to the maximum: 40 minus 16 equals 24 kits shipped. After delivery, on-hand rises to 40. If weekly usage then jumps to 12 kits, stock reaches the 18-kit trigger sooner (after roughly 1.8 weeks instead of 2.75), and the supplier ships again earlier. That responsiveness, driven entirely by the usage data you share, is the whole point of VMI. If you also model order cost against holding cost, an economic order quantity calculation can refine how much to ship each cycle rather than always filling to the maximum.
No. You delegate the replenishment decision, not visibility or ownership of your data. You still set the min and max levels, approve the item list, and should keep your own accurate stock and usage records so you can audit the supplier and reorder manually if needed. VMI works best when both sides see the same numbers.
A reorder point is a threshold your own team acts on. In VMI, the supplier owns that action: they watch your stock against the agreed reorder point (the minimum) and ship without you raising a purchase order. The underlying math is similar, but responsibility for monitoring and replenishing moves upstream to the vendor.
No. Fabrico tracks spare-parts consumption and stock levels as items are issued against work orders, giving you and your supplier an accurate, real-time usage signal. It does not place orders, auto-reorder, or manage supplier replenishment. VMI replenishment is handled by the supplier under your agreement, using the reliable data Fabrico helps you capture.
Want a clean, real-time record of what spare parts you actually consume, so your VMI supplier replenishes against fact instead of guesswork? Book a Fabrico demo and see how accurate consumption tracking becomes your inventory data foundation.
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