Consignment and VMI Stock
The Float Is the Decision

Why Consignment Looks Cheap Until You Count the Float

The pitch for consignment stock is seductive: put a rack of spares and consumables at the customer's site, let them draw what they need, bill them monthly for what moved. Sales love it because it removes the purchase decision from the customer. Finance rarely sees it for what it is, which is a working-capital loan that the distributor extends without an interest line and without a signed facility. A seeded rack at a mid-sized customer is routinely 8,000 to 20,000 USD of stock sitting on someone else's floor, and the distributor still owns every item on it until the moment it is consumed. That ownership is the entire economic question, and it is the one most consignment programmes never write down.

The second thing that gets lost is the shelf-life clock. A spare hotend sitting on a shelf for eighteen months costs almost nothing to hold. A spool of PA filament or a bottle of standard resin is a different asset: it is degrading from the day it is packed, and the customer is not going to accept a spool that has been on their own floor for two years. If the agreement does not assign that ageing to somebody, it lands on the distributor by default.

The 3D-Printing SKU Problem: Long Tails and Short Shelves

Distribution of fasteners or electrical components is a stable SKU problem, because the same catalogue sells for a decade. 3D printer distribution is not. Two forces make the parts tail unusually awkward to put on consignment.

The first is the length of the tail itself. A printer line generates dozens of small-value SKUs: nozzles in four diameters, three build-plate surfaces, extruder gears, thermistors, heater cartridges, fans, belts, PTFE tubing, and the sensor and board spares that sit behind them. The consumption curve is brutally skewed. In a typical installed base, roughly eight part numbers carry close to 90 percent of the pulls, and the last twenty numbers might each move once or twice a year. Seeding the full list is the standard mistake.

The second force is revision drift, which is specific to hardware that iterates quickly. A printer revised twice in three years strands spares that fit the earlier revision only. If those spares sit on a customer's floor under a consignment agreement, the distributor has parked obsolete inventory at a customer site and will eventually have to take it back and scrap it. The same is true of consumables with a chemistry-dependent shelf life: a resin formulation changed for a regulatory reason makes the previous bottles unsaleable regardless of the date printed on them.

Sizing the Float: Pareto, Not Generosity

The float should be sized from the customer's pull history, not from a wish to look well-stocked. The method is to take twelve months of that customer's parts orders, rank by line frequency rather than by value, and place the A-items on consignment first. Value ranking is the wrong sort: an inexpensive nozzle that fails monthly justifies more rack space than an expensive board that fails once. Frequency is what determines whether the customer experiences consignment as convenience or as clutter.

A workable three-tier structure for a single site consolidates to around forty lines, and rarely more:

• A-items, eight to twelve numbers. Consumed at least monthly. Float quantity equals roughly two months of that customer's observed pull, with a reorder trigger at one month. These are the items that make the programme feel valuable.
• B-items, twelve to sixteen numbers. Consumed a few times a quarter. Float equals one month of pull, restocked on the monthly reconciliation rather than in real time. Lower float, same service perception because lead time from the distributor's own warehouse is short.
• C-items, the rest. Not consigned. These stay in the distributor's warehouse and ship on demand. Putting a once-a-year part on a customer's rack parks capital for no service gain, because the customer was never going to need it faster than an express shipment delivers it.

The trigger discipline matters as much as the tiers. Set the reorder point so the rack is replenished before it empties, and let the monthly reconciliation drive the replenishment order rather than hoping the customer reports low stock. A consignment programme that depends on the customer telling the distributor it is running out has effectively delegated inventory control to the least motivated party in the arrangement.

Consignment vs VMI vs Sale-or-Return: Three Different Contracts

These three terms get used as synonyms and are not. The differences decide who holds the balance-sheet risk and who does the work, and the agreement needs to name which one applies to avoid arguing about it later.

• Consignment (strict). Title stays with the distributor until the customer consumes the item. The customer holds physical stock but owns nothing until draw. Settlement happens after consumption. The distributor carries all inventory risk including shrinkage, damage and obsolescence.
• Vendor-managed inventory (VMI). The distributor owns the replenishment decision and monitors stock levels, but ownership and settlement terms vary. In the version that protects the distributor, VMI is combined with a customer-held minimum or a floor commitment so that the distributor is not funding an unforecastable float indefinitely.
• Sale-or-return (SOR). The customer buys the stock outright and receives a right to return unsold or unused units, usually within a window and often subject to a restocking fee. This is not consignment at all, but it is frequently proposed as if it were, and it shifts the float cost to the customer while leaving the distributor exposed to the return.

The practical difference shows up in one line of the contract: when does title transfer? Everything else in the agreement, from who insures the stock to who counts it to who pays for a damaged unit, is downstream of that answer. Writing it down explicitly is what separates a programme that survives two years from one that ends in a dispute. The commercial terms that surround it, from payment structure to margin protection, are set out in our guide to distribution agreement contract terms and service level agreements.

The Risk-Allocation Table That Settles the Argument

The clause that causes the most argument is the one that was never written. Consignment stock at a customer site is exposed to four risks, and each one needs a named owner before the first rack is placed. If the agreement is silent, every one of them defaults to the distributor.

The two rows that need the most attention are obsolescence and end-of-agreement buy-back. Obsolescence is the one the distributor can actually control, by putting a dwell cap on every item: if a part has been on the rack for six months without moving, it rotates back to the distributor's warehouse on the next replenishment trip. That single rule prevents the slow accumulation of dead stock that makes consignment look unprofitable three years in. The buy-back row is the one that gets tested in practice, and specifying that the customer takes over the A- and B-items at cost while the distributor recalls the C-items removes the most common source of end-of-contract friction.

Settlement, Reconciliation and the Audit Trail

The commercial engine of a consignment programme is the consumption report, and it has to be produced on a schedule the customer has already agreed to. The month-end consumption file, reconciled against the on-hand count, is what generates the invoice. If that file arrives late or is disputed every month, the programme has failed operationally regardless of how good the pricing is.

Three practices keep it clean. First, count on the same day each cycle and have the customer sign the count sheet, so a shrinkage dispute is resolved against a shared record rather than memory. Second, reconcile the physical count against the transaction log every cycle and treat any difference over a stated tolerance, commonly two percent, as a real discrepancy to investigate rather than a rounding artefact to absorb. Third, keep the stock report and the consumption report as separate documents, because merging them hides exactly the discrepancy that the reconciliation exists to surface.

The audit trail also has a quality dimension. When a part on consignment turns out to be from a defective batch, the distributor needs to know which customers hold which lots, and the consumable side of that problem is the same one covered in our guide to filament lot consistency and filament lot traceability. A consignment rack that records only what left the distributor's warehouse, and not what lot sits at each site, cannot support a batch-level recall. That is a gap that is trivial to close at the point of seeding and very expensive to reconstruct afterwards.

When Consignment Loses: The Cases To Decline

Consignment is a tool and not a policy, and there are customer profiles where it destroys margin rather than building it. Declining these is a profit decision, not a service failure.

• Sites with low and irregular consumption. If a customer draws a part a few times a year, the float will age out before it is consumed, and the distributor will be rotating stock it never sold.
• Customers who will not accept monthly counts or audits. Without a count you cannot invoice reliably and you cannot contract out shrinkage. The whole risk-allocation table above assumes a counting discipline that a site unwilling to be counted cannot support.
• Customers with an unstable process. A plant that is changing its printer fleet every year will strand revision-specific spares faster than any dwell cap can rotate them.
• Accounts that are already slow to pay. Consignment adds a settlement step to an already extended payment cycle, and a distributor unwilling to fund a credit line for the customer should not fund a float instead.

The positive case is the mirror image. A site with steady monthly consumption, a stable machine fleet, an engineering team that will actually report low stock, and a signed counting discipline will convert a consignment rack into a durable revenue stream that is very hard for a competitor to displace, because replacing the distributor now means clearing a physical rack. That is the real return, and it is bought with the float.

Bottom Line

Consignment and VMI are inventory financing decisions dressed as a sales tactic. Size the float by pull frequency rather than by catalogue breadth, cap shelf dwell at six months so obsolescence cannot accumulate, name an owner for each of the four risks in writing, and invoice from a monthly consumption report reconciled against a signed count. Distributors who do those four things run consignment at a profit; those who skip the contract table discover the cost of the float three years later, when the stock has aged and the customer has moved to the next printer revision. For programmes that need to sit inside a broader working-capital plan, the cash-flow arithmetic is set out in our guide to distributor cash flow management, and the spillover risk of ageing stock is covered in end-of-life service parts planning.

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