What are failure codes?
Failure codes illustrate why an asset failed during production. Additionally, a failure code applied to a work order marks an instance of a particular failure behavior. The use of codes in a CMMS system ensures a consistent way of documenting the key aspects of the failure event according to pre-defined categories. Some examples include:
- Breakage
- Corrosion
- Imbalance
- Misalignment
- Overheating
- Vibration
Why are they used?
Failure codes are used in mining data in preventive maintenance software, which in turn makes subsequent analysis possible, which leads to net improved system availability. For example, the number of times an instance of a particular failure code occurs, divided by the total operating age of the equipment, approximates the failure rate. For maintenance organizations that don’t use failure codes, determining any sort of failure trend is a labor-intensive process of searching through work orders and making several educated guesses.
Why should you use them?
Knowing the failure rate for a failure code can help in doing the following:
- Optimize PM intervals
- Assess desirability of additional PM tasks
- Eliminate unnecessary PM tasks
- Improve failure response
- Improve work practices
The consistent use of the failure codes provides a convenient method of getting statistics about equipment failures or breakdowns. They aid your ability to effectively identify trends and problems. Let’s say that you have a fleet of similar machines. You could run a report for a period of time and, by selecting a failure code, determine how many times the failure occurs on an individual system. You can then compare this data across the entire fleet. If the failure rate is above average, it may be worthwhile proactively replacing parts or shortening the PM interval.
Having the correct codes and will also generate the types of reports and statistics that you require whether you are looking to improve OEE, or to implement a 6-Sigma or TPM program. These statistics are invaluable in any continuous improvement program. Codes can also help spot trends with work practices that cause the failures. For example, let’s say that you have equipment that has problems with contamination. You could run a report for a period of time and determine how many times your machine has had contamination problems. It could turn out the contamination is caused by a single technician who is over lubricating moving parts.
Who should input the codes?
Ideally, it is best to have the data entered correctly closer to the event by those who investigated and corrected the failure. In most cases, this is the technician that responds to the failure.
How many should you have?
Failure codes should provide an easy way to quickly analyze equipment failures, problems and faults. Without doubt, effective and accurate code lists are required for identifying trends but deciding what selection choices to place on such pick lists is no trivial matter. Too few and they would not support the level of data analysis desired or the data will be meaningless. Equally if there are too many options, technicians tend to suffer from “choice overload” and the default will become either the “Miscellaneous” or “Other” option, which will again render the data meaningless. Ideally, you should aim for 20-30 failure codes. Pop-up tables in the CMMS eliminate the need to memorize codes.
Who should develop them?
These codes should be easily available and understandable to the people who request work, to the maintenance personnel that complete the work and to the engineers who want to get the data they need to understand what is occurring in the field. Fault coding development really requires an integrated approach with these 3 groups, especially if there is a desire to do some sort of wide ranging analysis. Ultimately, the codes have to allow the field personnel a relatively painless way to provide the information that the engineers need. Unless that occurs, the end product will not be used.
Conclusion
In general, we collect failure codes for the purpose of analysis. Analysis, in turn, provides knowledge of equipment failure behavior patterns with respect to other external and internal factors such as “working” age, PM frequency, EHM parameters and decision models, operational tradeoffs etc. We can then use this knowledge to improve system availability and ultimately, the company’s bottom line.