Chronic versus Sporadic Failures – Which is Your Focus? – A Terry Wireman Blog Series
In their book “Root Cause Analysis – Improving Performance for Bottom-Line Results” Robert and Kenneth Latino define sporadic and chronic failures. (The following material is derived from pages 22-24.)
The sporadic occurrence usually indicates that a dramatic event has occurred. For example, there is usually a large business problem such as a breakdown, a fire or an explosion in a manufacturing or process plant or the company just lost a long-standing contract to a competitor. These events tend to draw a lot of organizational attention. Not just a passing note on the daily report, but urgent and immediate attention. In other words, everyone in the organization knows that something bad has happened. The key characteristic of a sporadic event is that they happen only one time with usually one failure mode. There is one failure mechanism at work that has caused this event to occur, so this is very important to remember. Sporadic failures have a very dramatic impact when they occur which is the reason many people tend to apply financial figures to them. For instance, you might hear someone say, we had a $10 million failure last year. So by their definition, the authors are tying sporadic events to what are normally referred to as equipment breakdowns.
Sporadic events are very important and they certainly are expensive however they do not happen very often. If a company had a lot of sporadic events, it would not be in business very long.
Chronic events on the other hand are not very dramatic when they occur. These types of events happen over and over again. They happen so often that they actually become the cost of doing business. We become so proficient in working on these events they actually become part of the status quo. We can produce are normal output in spite of these events. In the Japanese textbooks, chronic losses are often referred to as “Idling and minor stoppage losses”.
Some of the characteristics of chronic events include they are expected as part of the operational routine. Organizations accept the fact that they’re going to happen. In a typical plant, they even account for these events by developing a maintenance budget. A maintenance budget is in place to make sure that when routine events occur the money is available to fix them. These types of events demand attention but usually not the attention a big, sporadic event would. The key characteristic of a chronic event is the frequency factor. These chronic events happen repeatedly and for the same failure mode. For instance, on a given pump failure, the bearing may fail three or four times a year or, if you have a bottle filling line and the bottles continuously jam, these would be considered chronic failure events. Chronic events tend not to get the attention of sporadic events because, on their individual occurrences, they are not usually very costly. Therefore rarely would an organization ever assign a dollar figure to an individual chronic event. It becomes an accepted cost of doing business.
What most companies fail to realize is the tremendous affect the frequency has on the cost of chronic failures. A stoppage on a bottle line due to a bottle jam may take only 5 minutes to correct when it occurs. If it happens five times a day, it adds up to 152 hours of downtime per year. If an hour of downtime costs $10,000, then it becomes an annual loss of approximately $1.52 million.
As we can see the frequency factor is very powerful. But since companies tend to see chronic events in their individual state, they sometimes overlook the accumulated cost. Just imagine if we were to go into a facility in aggregate all the chronic events over a year’s time and multiply their effects by the number of occurrences. The yearly losses would be staggering. In the TPM textbooks from Japan, these types of losses (Chronic) always account for a higher percentage of the total losses in a plant than do the sporadic losses.
Why is this important? Just consider which type of losses receives a higher level of attention in your plant Sporadic or chronic? Do you spend more time on chronic or sporadic failures? What if you could eliminate 80% (applying some Pareto principle) of all of your chronic failures? What would that do to your overall maintenance costs? What would it do to the capacity of your plant? It is seen in the majority of chronic failures that workmanship (either from maintenance or operations) is responsible for the majority of these failures/ losses.
In the majority of cases, organizations are quick to reward the Hero who can quickly repair a sporadic loss. However, they never reward the artisan technician whose skills can eliminate chronic losses.
Which behavior does your organization reward? Perhaps a read of the Root Cause Analysis textbook would help you improve your bottom line.