This post provides information about Causal Factors relating to deviation and defects.
By Chris Vallee, Senior Associate, TapRooT®
Hint, there is usually more than one Causal Factor that:
- caused the deviation/defect
- failed to catch/stop the deviation/defect, and
- failed to mitigate the quality escape when the deviation/defect reached the internal/external customer.
Let's start with a few definitions.
QUALITY ESCAPE: Any product or service containing a deviation/defect that is released from point of origin, whether caught before it reached the end external customer or not. Definition Reference
Important Question: Is it a quality escape if the product or service met design/customer specifications?
DEVIATION/DEFECT: A product or service that does not meet required and documented specifications and/or can not be used by the end customer per its intended use. Definition Reference
Important Questions: Is it a defect if made to specifications?
If the defect is corrected on the spot would you analyze for Causal Factors or Root Causes?
CAUSAL FACTOR: A mistake, error, or failure that directly leads to (or causes) an incident or that fails to mitigate the consequences of the original error.
- An action someone performed?
- An action, a piece of equipment, component, or process transaction performed?
- An action not performed by someone?
- An action not performed by a piece of equipment, component, or process transaction?
Important Note: We do not fix Causal Factors, we fix Root Causes that allowed, encouraged, or failed to prevent the Causal Factor from happening.
ROOT CAUSE: The absence of a best practice or the failure to apply knowledge that would have prevented the problem (Causal Factor) or would have significantly reduced its likelihood or consequences.
Back to finding Causal Factors. As stated earlier, there is usually more than one Causal Factor that caused the defect, failed to catch/stop the defect, or failed to mitigate the quality escape when the defect reached the customer. Experts are often quick at finding the Causal Factor for the defect. What are often missed are Causal Factors that:
- failed to catch/stop the defect, and
- failed to mitigate the quality escape.
Let’s stop and think for a second: how many source inspections, in-process inspections, no-go mistake-proofing safeguards, and eyes-on and touchpoints have companies built into most of their quality systems? How on earth could these fail to catch a defect or allow it to escape forward to the next customer?
Here are some common failure points to discuss:
- Does the assembler or inspector have working knowledge of how their task completion point fits into the final product or service to the customer?
For example, an assembler drills an alignment hole into a sub-assembly per blueprint and the inspector stamps the part off as per specification. The part is forwarded to final assembly. The final assembler uses the alignment hole to drill a hole in the final assembly and drills into another component, damaging it.
Would you have identified the part being passed per specification as a Causal Factor? You should, because this is a touch point that could have prevented an internal quality escape.
- The damage to a part that creates repair or rework is assigned as the cause of the defect as opposed to just treating it as a point of discovery that needs to be investigated. Often, this encourages an unauthorized correction to “make it work”.
In the example above, final assemblers moved the part over slightly to ensure that it would not be drilled into while drilling through the alignment hole, which prevented future quality rework requiring quality notifications. This again would be another Causal Factor to be analyzed for root causes.
These are just a few ideas to get your mind in gear for finding accurate Causal Factors to then be analyzed for effective Root Causes to prevent future Quality Escapes.
(Republished with Permission. The original post can be found here).
TapRooT® Root Cause Analysis is used to improve performance by analyzing and fixing problems to prevent major accidents, quality issues, equipment failures, environmental damage, and production issues. Click HERE for more information.
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