As we all know, in the world of maintenance and reliability, there are hundreds of things vying for attention. How do we decide where to expend our valuable resources? It doesn't matter if we're talking about money, people, time, effort, materials or contract help; we want to focus on the equipment that is most critical and valuable to our operation, but which equipment is that? The answer to that question comes in the form of using a quantifiable and objective criticality ranking process.
The objective of performing a criticality ranking on you asset base is to determine which assets are most important to the overall operation. Traditional ranking or priority codes often differentiates equipment by using an "A-B-C" or "Hi-Med-Low" type of ranking. The problem with this ranking is that it is often done by one person and is very subjective and often no more than an educated opinion of one person. How many of us have these types of codes in our systems? How many of us never actually use the coding for any type of decision making?
Let's look at it another way. If you were to evaluate your equipment using the A-B-C method above would you get the same answer if you asked the Maintenance Manager and the Operations Manager to rank a piece of equipment? How about if you asked the Safety Department? The Environmental Manager? How about the Quality Control Manager? With this method there is a good chance you will have differing opinions and if you extrapolate this across all of your equipment then you can see that you may get conflicting priorities.
Our Maintenance Tip is utilizing a ranking process that is objective and quantitative and incorporates ranking criteria for all of the primary function and areas of concern. We usually use the five functional areas of Maintenance, Production, Safety, Environmental and Quality. We then utilize a cross-functional team to develop subjective weighted criteria based on business requirements for each of these functional areas. An example of the weighted criteria for the "Maintenance" Functional Area would be:
- Down Time Impact - What is the potential downtime impact if this equipment fails
None 0 pts Minutes 125 pts Hours 150 pts
Shift 200 pts
Multiple Shifts 250 pts
Days 400 pts - Repair Costs - What is the typical (average) cost to repair a failure on this equipment
None 0 pts
10,000 300 pts - Spare Parts Availability
In line Spares 0 pts
Spares In Stock 50 pts
Spares lead time 3 days or less 150 pts
Spares lead time > 3 days 300 pts - Affected Down Time Area - How much of the plant may be affected by failure
None 0 pts
Component Only 50 pts
Line 150 pts
Department 250 pts
Plant 500 pts
Similar criteria for all of the functional areas would also need to be developed. Using this type of set up the equipment with the highest point ranking is the most critical.
It is important to note that the criteria and the weighting will be different from plant to plant and industry to industry due to business issues. This is why it is important that the weighting and criteria be developed with representation and agreement from all areas of the plant. The key to an effective criticality ranking is to correctly configure the Criticality Ranking Tool (CRT) to incorporate all perspectives of the equipment. Set-up includes determining the ranking criteria for each area and also properly weighting the criteria to accurately reflect the criteria's relative importance to the organization. If the criteria are measurable and the whole organization agrees with them then a smaller team of knowledgeable personnel can actually rank each piece of equipment.
A spreadsheet or database can be set up to manage the information or you can purchase software for this purpose.
The completed ranking can then be used to determine which equipment gets attention first, how the maintenance strategy gets developed and what type of maintenance is performed. The overall ranking can even be loaded into the CMMS and be used to help prioritize work orders.
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