Vendor Managed Inventory for Industrial Components — How It Works and When It Pays Off
Why vendor managed inventory is back on the procurement agenda
Vendor managed inventory (VMI) is a supply model in which the supplier monitors the buyer's consumption, holds the buffer stock and triggers replenishment — so production calls off components when it needs them, instead of procurement ordering against a forecast.
VMI pays off when three conditions are true. Demand varies more than your lead time can absorb, the safety stock you carry to cover that variance is a material share of your working capital, and your supplier is genuinely able to hold the buffer for you. When those conditions are not met, VMI adds a contract and a data feed without removing any cost.
For most industrial components the question is not whether VMI lowers the unit price. It rarely does. The question is where variance, capital and obsolescence risk sit, and who is paid to manage them.
That is the short answer. The rest of this article separates VMI from the models it is usually confused with, breaks down the three cost lines it changes, explains why ownership of the stock matters more than most contracts admit, and sets out a five-question test you can run on your own component portfolio.
What is VMI — and how is it different from consignment stock, bill-and-hold and kanban?
The four terms are often used as if they were the same thing. They answer different questions.
Vendor managed inventory answers who decides when to replenish. The supplier does, based on the buyer's consumption data and agreed minimum and maximum levels.
Consignment stock answers who owns the stock. The supplier does, until the moment the buyer consumes it. Consignment stock usually sits at the buyer's site.
Bill-and-hold answers who holds stock that has already been invoiced. The supplier keeps physical possession of goods the buyer has been billed for and transfers them later. IFRS 15 defines the arrangement explicitly and sets strict conditions for it.
Kanban answers how the replenishment signal is sent. It is a signalling mechanism — a card, a bin, a scan — and it can run inside a VMI agreement or entirely without one.
The distinction matters because VMI on its own says nothing about ownership. A supplier can manage the replenishment of stock the buyer owns, or of stock the supplier owns. Mixing those two up is the most common source of disappointment in VMI agreements — a CFO is promised a balance sheet effect that the contract never delivers.
Driver 1 — Safety stock is the most expensive inventory you never discuss
Safety stock exists for one reason. It covers the spread between the demand and lead time you expect and the demand and lead time you must be able to survive.
The wider that spread, the larger the buffer. And as we set out in our analysis of nearshoring component sourcing, the spread has widened considerably — freight volatility, longer supply chains and forecast error at long horizons all push in the same direction.
The cost of that buffer never appears on a purchase order. It appears as capital tied up at your cost of capital, as warehouse space, handling and insurance, and as the planner hours spent counting, moving and re-sequencing it.
VMI does not make the variance disappear. It changes who holds the buffer, on what signal it is replenished, and on whose balance sheet the capital sits during the waiting period. Whether that is a real saving or a cost moved between two columns depends entirely on the contract — which is why the ownership section below is the most important part of this article.
Driver 2 — A stockout costs far more than the missing part
When a component runs out, the visible cost is the expedite — the air freight, the express machining run, the premium paid to a secondary supplier.
The invisible cost is larger. An idle line. Operators reassigned or sent home. Downstream operations rescheduled. Overtime to recover the lost hours. A late delivery to your own customer, and the conversation that follows it.
Most of those costs are booked to production or logistics, not procurement, so they rarely make it into a supplier comparison.
Calendar-based replenishment is a structural cause. Orders placed on a fixed schedule against a forecast made months earlier will run short whenever actual consumption runs ahead of it. VMI replaces the calendar with a consumption signal — when stock falls to the agreed minimum, replenishment is triggered, regardless of what the forecast said in March.
Driver 3 — Obsolescence risk sits with whoever holds the stock
This is the driver procurement teams most often leave out of the VMI business case, and the one suppliers most often leave out of the VMI contract.
Components become obsolete for ordinary reasons. An engineering change notice moves a part to a new revision. A product is discontinued earlier than planned. A customer programme is cancelled. A slow-moving spare part sits for years.
Every unit of stock built against a forecast is exposed to that risk. The question in a VMI agreement is not whether obsolescence happens. It is who pays for it when it does.
The honest answer is that it is usually shared. A buyer who commits to forecast or framework quantities remains liable for stock built against that commitment, while the supplier carries the risk on anything produced beyond it. That is reasonable — but only if the split is written down before the first revision change, not negotiated after it.
Who owns the stock — and why it matters for your balance sheet
Inventory sits on the balance sheet of whoever controls it, not whoever physically holds it. A component on your supplier's shelf can still be your inventory. A component in your own warehouse can still belong to your supplier.
That makes ownership the decisive term in any VMI agreement that is meant to improve working capital.
Three ownership models in practice
Supplier-owned until call-off — the supplier owns and holds the stock, and ownership transfers when production calls it off. The inventory stays off the buyer's balance sheet until consumption. The supplier carries the capital cost and will price it into the part, explicitly or implicitly
Buyer-owned, supplier-held — the buyer has been invoiced and owns the stock, but the supplier holds it. Under IFRS 15 paragraphs B79–B82 this is a bill-and-hold arrangement, and it only qualifies when the reason for it is substantive, the goods are separately identified as the buyer's, they are ready for physical transfer, and the supplier cannot use them or send them to another customer. The stock is on the buyer's balance sheet
Committed but not yet invoiced — the buyer has committed to forecast or framework quantities, the supplier holds the stock and invoices on call-off. The cash outflow is deferred until consumption, but the buyer carries the commitment and the obsolescence liability that comes with it. How this is treated in your accounts depends on where control sits in the contract
The last point deserves emphasis. Whether a VMI arrangement improves your balance sheet is a question for your auditor, answered from the contract — not from a supplier's sales material.
What to check in a VMI contract
The ownership transfer point — on receipt into the supplier's stock, on call-off, or on consumption
The invoicing trigger — and whether it matches the ownership transfer point
The maximum holding period — and what happens to stock that exceeds it
Minimum and maximum levels — who sets them, and how often they are reviewed
Obsolescence on revision change — who pays for stock built against the old revision
Data sharing — what consumption data the supplier receives, and how often
Run-out and exit terms — how stock is cleared if the agreement ends
Buyer-managed stock vs vendor managed inventory — a practical comparison
Factor | Buyer-managed stock | Vendor managed inventory |
Replenishment decision | Buyer, from forecast | Supplier, from consumption data |
Replenishment trigger | Calendar or reorder review | Agreed minimum level reached |
Safety stock sizing | Set by buyer, often by habit | Set jointly against measured variance |
Warehouse space and handling | Buyer | Supplier |
Working capital effect | Full buffer on buyer's balance sheet | Depends on ownership transfer point |
Stockout exposure | Buyer | Contractually shared, mostly supplier |
Obsolescence risk | Buyer | Split by contract — commitment vs overproduction |
Expedite cost | Buyer, often booked outside procurement | Supplier, within agreed demand range |
Purchase order volume | One per replenishment | One framework, call-offs against it |
Data requirement | Internal only | Consumption data shared with supplier |
The honest conclusion matches the one from our total cost of ownership breakdown. VMI does not win on unit price. It wins on the lines that never appear in a unit price comparison — and it only wins on working capital if the contract says so.
What VMI actually looks like in practice
Most VMI commentary describes the model as a software integration. In practice it is an operating agreement, and it works when four things are in place.
Consumption data flows, purchase orders do not. The supplier needs to see what production actually uses — weekly at minimum, daily for fast-moving parts. That does not require an EDI project. A shared consumption report or a scanned bin is often enough to start.
The buffer is sized to variance, not to habit. Minimum and maximum levels are calculated from measured consumption spread and the supplier's real replenishment lead time — and reviewed when either changes. A buffer copied from the old reorder point carries the old inefficiency into the new model.
Replenishment is the supplier's problem, run-out is a joint one. The supplier is accountable for keeping stock between the agreed levels. The buyer is accountable for flagging engineering changes, programme ends and demand shifts early enough for the buffer to follow.
One stock point for multi-process components. VMI pays off most when a cast, machined and surface-treated part — or a full sub-assembly — is held as one finished item by the party responsible for the whole chain. That is where VMI connects with one-stop-shop component supply and assembly and boxbuild. Three suppliers each holding a buffer of a semi-finished part is not VMI. It is three inventories.
A five-question test for your own component portfolio
Take your top twenty components by annual spend and run these five questions against each.
What is the value of the safety stock you hold for each component, and what does it cost per year at your cost of capital plus storage and handling?
How many stockouts and expedites did you have in the last twelve months, and what was the fully loaded cost — including idle line time and overtime, not only freight?
How accurate is your forecast at the supplier's lead time horizon — not at one month, but at the point where the order is actually placed?
How much stock have you written down or scrapped over the last three years because of revision changes, discontinued products or slow movers?
If a supplier held the buffer for you, which contract term would decide the business case — the ownership transfer point, the holding period or the obsolescence split?
Components that score high on the first four questions are VMI candidates. The fifth question tells you what to negotiate.
Frequently asked questions
What is vendor managed inventory? Vendor managed inventory is a supply model in which the supplier monitors the buyer's consumption, holds buffer stock and triggers replenishment within agreed minimum and maximum levels. The buyer calls off components as production needs them instead of ordering against a forecast.
What is the difference between VMI and consignment stock? VMI describes who manages replenishment. Consignment stock describes who owns the inventory — in a consignment arrangement the supplier owns the stock until it is consumed. The two can be combined, but a VMI agreement does not automatically include supplier ownership.
Does vendor managed inventory take inventory off the balance sheet? Only if ownership and control remain with the supplier until call-off or consumption. If the buyer has been invoiced or has taken control of the goods, the stock belongs on the buyer's balance sheet even when the supplier holds it. The accounting treatment follows the contract terms and should be confirmed with your auditor.
Which components are best suited for VMI? Components with steady but variable consumption, meaningful safety stock, line-critical status and a stable design. Multi-process components and sub-assemblies benefit most, because one stock point replaces several buffers. Highly customised one-off parts and components facing an imminent revision change are poor candidates.
Do we need an ERP integration to start VMI? No. Many VMI agreements start with a weekly consumption report or a two-bin system and add system integration once volumes justify it. What matters is that consumption data reaches the supplier reliably and on a fixed rhythm.
How long does it take to set up a VMI agreement? For components already in supply, a few weeks — the time needed to agree levels, data flow and contract terms and to build the initial buffer. For new components, VMI starts once the part is qualified and in series production.
Where Pamatek fits
VMI is built into how we supply components rather than offered as an add-on.
Pamatek holds committed components in our Danish stock free of charge for up to ten months, replenishes on your consumption signals rather than a calendar, and absorbs the demand variance that would otherwise sit in your own warehouse. Because we deliver across metal casting, die casting, CNC machining, surface treatment and assembly through one coordinated supply chain, the buffer is held as one finished part — not as semi-finished stock spread across several suppliers.
The outcome for our customers is a shorter planning horizon, fewer stockouts and fewer expedites, and one counterparty accountable for keeping the line supplied. The terms behind it are written down from the start.
If you want to know what VMI would change on your own components, send us your top twenty parts with annual volumes and last year's consumption. We will return a buffer proposal and a working capital picture you can take to your CFO.
Sources — Commission Regulation (EU) 2016/1905 adopting IFRS 15 Revenue from Contracts with Customers, Appendix B paragraphs B79–B82 on bill-and-hold arrangements. Accounting treatment is summarised for orientation and does not constitute accounting advice.
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