Maintenance and reliability engineers will happily (well, not happily) undertake a review of spare parts that are not classified as critical, yet they will shy away from reviewing items that are classified as critical. The argument is: ‘the item is critical and so we must stock it'. Thus the classification drives the review action rather than a cost benefit or stocking analysis. But what if the classification was wrong, or the item was significantly overstocked, or the supply arrangements had changed? Surely these are factors that can be reviewed and have nothing to do with the part's criticality?
It doesn't make sense to limit your review action based on the idea of criticality alone. This will drive you to review parts that are critical but not defined as such and not review parts that are defined as critical but which may no longer be critical. Classifying an item as critical tells us that we need to have ready access to the item when it is required, it doesn't tell us what the alternatives are or how many we need to carry. Nor does it tell us whether we need to actually own the items prior to needing them. Don't shy away from reviewing critical items. They may be just as overstocked as any other item, or there just might be a viable alternative to holding the item at all.
Phillip Slater is a leading authority on materials and spare parts management. He is a qualified engineer, an experienced operations and maintenance manager, a seasoned management consultant, and the author of four operations management books, including Smart Inventory Solutions, now in its second edition. www.PhillipSlater.com