Hazard to say but you are going to get a long and diverse list of advice on this subject! Surely you have Googled the topic as a reliability person and seen the list of spare parts analysis options that is never ending. (And many software solutions of course to "help" you!) Often the method of spare parts analysis you use will define these classifications of spares.
It comes down to those spare parts that the organization cannot be without (critical) and those where there is some margin for availability (non-critical - aka, everything else). How the non-criticals are organized is not always so important, but they can be classified none the less.
A critical part is one that is related to an equally critical asset (equipment) or process. That's an easy estimation.
But you could have a "critical" part that is due to its long lead time to acquire or without it the asset is unsafe.
FMECA analyses help in this area because they eventually define what is critical and what is not in the "system" being looked at. Then, any spare related to something critical is deemed as such.
Even criticality can have its nuances. Is the criticality due to safety, production losses, lead time, etc. What really is a "critical spare part?"
A commonly available O-ring can become critical overnight if for some reason the parts bin is empty, causing the equipment to be down for far longer than it typically is.
If the equipment cannot function or perform as expected (windows of downtime, out/throughput, etc.) and safely, without the spare part, then the part is critical. Safety often trumps everything when it comes to criticality. Can a saw be operated without a hand guard? Yes. Safely? No. Therefore, the hand guard as a spare part is critical. (Or have a backup saw(s) available and toss the one with the broken hand guard. Maybe now the backup saws are critical "spares"?) ;-)
Had an instance once where a red light bulb was determined to be the most critical spare in the system since it was a safety indicator for humans. Even the built-in safety interlocks were deemed a lesser level of criticality in that case.
"Insurance" stock I am assuming is like buffer stock or minimum level of stock... that is usually defined via the analysis, so not much to say there.
Hope this helps. Chasing spares is a never-ending adventure!
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John Q. Todd
Sr. Business Consultant/Product Researcher
Total Resource Management
john.todd@trmnet.com------------------------------
Original Message:
Sent: 01-26-2025 07:30 AM
From: Lesiba Moja
Subject: Spare parts allocation
Let's Talk Spare Parts Management!
Spare parts categorization is a critical aspect of effective asset management, but it's often a topic of debate. I'm curious to hear how you differentiate between these key categories:
๐น Operating Spares
๐น Capital Spares
๐น Insurance Spares
๐น Critical Spares
From your experience:
- What criteria do you use to classify spares into these categories?
- How does this categorization impact your inventory strategies or maintenance planning?.
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Lesiba Moja
Reliability Coordinator
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