But how much should actually be kept in stock? Is a Just-in-Time approach sufficient, where parts are only procured when needed? Or is a safety buffer necessary to cushion unforeseen failures - perhaps only for certain parts?
In addition, there are other principles such as FIFO, LIFO, or On-Demand that can help with the optimal organization of spare parts storage.
In this article, we compare these approaches, explain advantages and disadvantages, and provide helpful tips on how to avoid common mistakes.
Just-in-Time: Less inventory, higher risk
With the Just-in-Time (JIT) approach, parts and materials are only procured or delivered when they are actually needed. This reduces storage costs and ties up less capital. For maintenance, this means relying on fast procurement through suppliers or partners instead of keeping expensive stock on shelves. This approach is particularly suitable for standardized, readily available parts and especially for planned maintenance or repairs. However, the downside is clear: if an unexpected failure or delivery delay occurs, it can lead to extended downtimes. In maintenance, where time often equals money, JIT is therefore risky for critical components.
Safety buffer: Always prepared
A safety buffer in spare parts storage means that companies deliberately keep additional stocks on hand to be able to react at any time. This ensures high availability and reduces the risk of prolonged machine downtimes. Especially for rare or critical spare parts that are difficult to obtain, a buffer stock is often indispensable. The downside: storage requires space and ties up capital. Moreover, parts that are rarely needed may become outdated or unusable.
FIFO, LIFO, and On-Demand: Organizing what’s on hand
Besides the question of how much to store, there is also the question of how to organize inventory. Established principles can help:
FIFO – First In, First Out: The oldest part is used first. This prevents spare parts and materials from becoming obsolete or unusable. Particularly useful in maintenance for wear parts or materials with limited shelf life, such as lubricants or seals.
LIFO – Last In, First Out: The most recently received part is used first. LIFO can be practical in warehouses without complex shelving or conveyor systems, since the front (newest) items are taken first. This works well when there are no expiration dates or similar concerns, but it is risky since older stock may be left unused.
On-Demand: Parts are only ordered when the actual need arises. Some companies already rely on this method, procuring parts only after a defect occurs. This saves storage costs but significantly extends downtime and is often unsuitable for critical parts.
Avoiding common mistakes
A good spare parts storage strategy in maintenance helps avoid frequent pitfalls:
-
Insufficient risk analysis: Not all parts are equally critical. Stocking everything wastes money.
-
Wrong priorities: Important spare parts are missing while less relevant ones are overstocked.
-
Lack of transparency: Unclear inventories result in double orders or overlooked items. A digital warehouse management system (WMS) or spare parts management tool can help.
-
Obsolete stock: Without FIFO or regular checks, spare parts can become unusable. Digital systems also make it easier to maintain an overview of stock.
Conclusion: Finding the right balance
In maintenance, neither extreme Just-in-Time nor unlimited stockpiling makes sense. The optimal strategy combines buffer stocks for critical, hard-to-source parts with lean processes for standard components.
A well-thought-out storage concept ensures machines are back in operation as quickly as possible — without unnecessarily tying up capital in inventory.
Companies that regularly analyze spare parts needs, set clear priorities, and organize stocks transparently remain able to deliver and competitive — even when unforeseen issues arise.
