Process Failure Modes and Effects Analysis (PFMEA) From the Process Flow to Production

PFMEA is a tried and tested approach to critique risk. Its purpose is simple, to identify potential failures, their consequences, the seriousness of the consequences and the reasons why they happen. Control methods are considered in two ways:

The first being activities in place which reduce the likelihood of the reasons for failure happening. The second being activities which tell you when a failure has occurred and thus enabling you to do something about it.

The overall purpose is to establish where the high risk areas are based on the current situation and then take action to reduce the risks. The approach taken and the timing of the task are instrumental to achieve maximum payback. When used correctly it is one of the singly most powerful quality tools available to companies. Process FMEA used in isolation like this is very thorough, but a missed opportunity to reap the full intended benefits of the document.

PFMEA strategy

Process Flow Diagram

The starting point is not the PFMEA but defining the process in the process flow diagram. Care must be taken here to select the correct wording and level of resolution. The output of process flow diagram must then be synchronised with the input to the PFMEA so that you critique the correct aspects of the process for risk.

PFMEA

You now compile your PFMEA in terms of failure modes, effects, severity of effects, causes of failure, prevention controls, occurrence, detection controls and their ranking followed by priority. At this stage it is still important to have recommended actions to reduce risk. However you now need to bring the PFMEA to life through the practical deployment of the content of the PFMEA to production. Primary data being the prevention controls to avoid failure and the detection controls to detect failure at the various stages of the process as defined in the process flow.

Production documents

It is essential that the primary data contained within the PFMEA is displayed at the point of use in plain view to the person who needs to know and act on the data. Failure to do this simple but necessary task will result in a company being exposed to the latent risk of a loss of process control, often resulting in customer complaints. Deployment typically is through the use of visual instructions located where the task takes place, sometimes the data flow is via the control plan (automotive sector), although this does depend of sector specific requirements.

Key points for consideration are:

Sufficient resolution of the process steps in the process flow diagram. The data contained in the process flow diagram is synchronised to the functional requirements column on the PFMEA. PFMEA is a true reflection of the current situation, as a living document. The prevention and detection controls defined in the PFMEA are communicated to the person carrying out that particular step of the process at the location where the task is undertaken. Appropriate reaction planning is identified at the process step location to clearly identify what to do if a failure is identified.
Summary

This article is intended to provide an overview of the necessary linkage of the PFMEA to achieve maximum benefit to a business who are considering the utilisation of PFMEA for the first time or are existing practitioners but don't believe they are reaping the true benefits that PFMEA can deliver.

Roger Thorpe has been an FMEA facilitator and consultant for 13 years. Many of his customers being tier 1 automotive manufacturers. For more information on PFMEA construction from an expert visit his website: http://www.fmea.org.uk