Every product that stays in a catalogue long enough meets this moment. A component is discontinued, a material is reformulated, a subassembly is replaced by its successor, or a factory simply stops making the version you buy. Sometimes it arrives as a formal notice; more often it arrives as a quotation that has become strangely expensive, a lead time that has doubled, or an answer saying the item is temporarily unavailable in a way that turns out to be permanent. The companies that come through it without an emergency are the ones that treated the notice as the start of a project rather than as a piece of news.
The notice, and the time it really leaves you
A proper notice is a specific document: it names the reference being discontinued, the successor if there is one, a last date for placing orders and a last date for shipment. Those last two are not the same thing, and the gap between them is often where the whole plan lives. Read both, then read who it was sent to — these notices travel to the person who places orders, and the people who need them are the ones who design the product and the ones who promised a service life to a customer.
The time it leaves is always shorter than it reads, because the replacement has to be chosen, sampled, tested and approved inside that window, and so does any certification file the change touches. Which is why the first action is not a purchase order: it is to establish, in a few days, which of your products use that reference and what each of them has promised. A company that cannot answer the first half of that question quickly will discover the answer one angry customer at a time.
Sizing the last buy
- Decide how much longer the product that uses it will be sold. Not how long you hope: the date after which you would discontinue it anyway. Every figure below hangs on this one, and it is a commercial decision rather than a purchasing one.
- Add the production you will actually run in that period, taken from the forecast you would defend in front of your bank rather than the one in the sales plan.
- Add the spare parts and warranty returns for the whole period you have committed to support, which usually runs well past the day you stop selling the product.
- Add what the process destroys: scrap, test samples, the units lost in setting up a run. A component counted at its net requirement comes up short on the last batch.
- Subtract what you can reasonably expect from the replacement arriving earlier than the stock runs out — and be honest here, because this is the line everyone uses to make the number smaller.
- Then check the result against two constraints that have nothing to do with demand: the cash it ties up, and whether the item survives storage for that long at all.
Both ways of getting it wrong are expensive, and they are expensive differently. Too small, and you pay for a redesign under time pressure, air freight for a substitute, or a product withdrawn from sale for a season. Too large, and you have frozen cash in something that ages: tape on reels that oxidises, adhesives and elastomers that harden, batteries that will not take a charge, a material with a shelf life that nobody read. Storage conditions are part of the calculation rather than a detail, and so is the possibility the product itself is stopped before the stock is used — which happens more often than anyone plans for.
Qualifying a replacement
« Drop-in replacement » is a claim made by the party that wants the change to be easy. Sometimes it is true. What has to be checked is everything the word drop-in quietly covers: the physical footprint and how it is held, the behaviour at the edges rather than in the middle of its range, the firmware or the control sequence that addresses it, the tolerance stack it sits in, the colour and the surface after ageing, and the regulatory file the original sat inside. A part that is electrically identical and mechanically a fraction different is not a drop-in for an automated assembly line.
The cost of the change is rarely the price difference. It is the testing, the certification file that has to be amended where the change touches a characteristic the marking relies on, and — the one people forget — your own customer's approval, which can take longer than everything else put together in an industry where parts are qualified by the buyer. All of which is the argument for naming a second source at design time, when it costs an afternoon, rather than at end of life, when it costs a requalification.
Spare parts, and what you promised the customer
The commitment that binds you is rarely in a brochure. It is in a warranty duration, a service contract, a tender you won, or an expectation created by the kind of product you sell — a machine bought to last a decade carries an assumption about parts whether or not anyone wrote it down. European product rules increasingly attach repairability and spare-part availability obligations to specific categories of goods, with the scope and the duration depending on the category and on the text in force; if your product might be covered, that is a question for the applicable text rather than a general answer.
Practically, there is a difference between a part you hold and a part you can still have made. For a moulded or machined part the tooling may survive the supplier's catalogue decision, which turns a stock question into a storage question — who keeps the mould, in what condition, and who pays for the space. For a bought-in electronic component neither is available, and the honest route is often to support the product at subassembly level instead: keep complete boards rather than components, and replace the module. Whatever you choose, say it to the customer in advance. A stated support period that you honour is worth more than an unlimited one you will quietly stop honouring.
Stopping a reference cleanly
- Tell the customers before the stock runs out, not after. A buyer given notice places a final order and stays a customer. A buyer who discovers it when an order is refused goes looking for your competitor's catalogue.
- Name the successor and how to move to it. What changes, what does not, what has to be requalified on their side. A notice without a successor is a problem handed over; a notice with one is a service.
- Carve the spare-part reserve out of the last buy, and separate it physically. A reserve stored with the production stock is consumed by production, always, and the discovery is made on the first warranty claim after the line closes.
- Settle the tooling. Scrapped, stored, or returned to you — with a written answer to who owns it, who stores it and who pays. Tooling nobody decided about is tooling that disappears during a factory move.
- Archive the file, not just the part. Drawings, the approved sample, test reports, the certification file, the supplier's own references. The reference can then be rebuilt elsewhere years later, which is the only real insurance against this situation.
All of which is easier if the contract said so. The clause worth having obliges the supplier to notify a named person — not an inbox — a stated period before any change or discontinuation, gives you a defined window to place a final order at the current price, and requires that the tooling and the documentation come to you when a reference is stopped. Add one sentence that is usually missing: the same obligation applies to the components the supplier buys in, because the discontinuation that will hurt you is almost never theirs. None of this is negotiated at signature, when nobody is thinking about the end, and all of it is wanted later, when the notice has already arrived too late.
Keep one list, updated when a product changes rather than once a year: for each reference you buy, which of your products use it, which single supplier makes it, and what you have promised the customers who own those products. The list is tedious and short. It is also the difference between a discontinuation notice that starts a project and one that starts a search through old drawings.