In a manufacturing plant, not all parts carry the same level of risk.
Some can be replaced easily, ordered quickly or temporarily substituted. Others, sometimes simple and inexpensive, can bring an entire production line to a halt when they become unavailable.
That is the difference between a replacement part and a critical part.
The challenge? Many businesses only discover which parts are truly critical… when they break.
A Critical Part Is Not Necessarily an Expensive Part
It is tempting to rank parts by their purchase price. Yet price tells you little about their true operational importance.
Imagine a $500 machined part installed in an essential piece of equipment.
It breaks.
No replacement part is available.
The original manufacturer no longer stocks it, and your supplier must reproduce it as a custom part.
That $500 part can then leave the equipment out of service for several days.
Its true strategic value is therefore not $500.
It lies primarily in the consequences of its unavailability.
That is why identifying critical parts must begin with a different question:
What happens if this part becomes unavailable tomorrow morning?
5 Criteria for Identifying a Critical Part
1. Its Impact on Production
This is the first criterion.
If the part breaks, can the equipment keep operating?
Can production be moved elsewhere?
Is there a temporary solution?
The more quickly a failure causes significant downtime, the more likely the part should be considered critical.
2. Its Replacement Lead Time
A part available locally within a few hours generally poses less risk than a custom part that takes several days or weeks to manufacture.
You therefore need to know the actual time between a failure and the point when a replacement part that meets specifications can be installed.
3. The Availability of Its Documentation
Do you have the drawing?
The dimensions?
The tolerances?
The material specifications?
The required treatments?
When a part breaks, discovering that the only available drawing is several years old, or that the part must be reverse-engineered from the damaged component, adds considerable risk.
4. The Availability of a Replacement Option
A readily available standard part generally poses less risk.
By contrast, a proprietary, non-catalogue, obsolete or custom-made part can become strategically important, even if it rarely breaks.
5. The Likelihood of Failure
Finally, review its history.
Does the part wear out regularly?
Has it caused downtime before?
Does it operate in a harsh environment?
Is the equipment ageing?
A part that combines high impact, a long procurement lead time and a high likelihood of failure deserves particular attention.
Start With Your 10 Most Critical Parts
You do not need to map out the thousands of components in your plant right away.
Start with your most important equipment.
Then identify the parts whose unavailability could have the greatest consequences.
For each part, document at least:
- its impact on production;
- its replacement lead time;
- the availability of the drawing;
- whether an alternative solution exists;
- its failure history;
- whether a spare part is available.
You will quickly gain an initial overview of your risks.
Identification Is Only the First Step
Once you have identified your critical parts, different strategies become possible.
For some, better documentation may be all that is needed.
Others can be kept in inventory.
And for certain custom parts that pose a high risk, proactive machining may be a suitable approach: the part is manufactured before a failure occurs so that it is available when needed.
The goal is not to stock every part.
The goal is to secure the ones whose absence could seriously compromise your operations.
A Question to Get Started
If one of your parts failed tomorrow morning, which would be the hardest to replace?
You may have just identified your first critical part.