Paul K

Z allows for comparisons and evaluations of process performance. Performance expressed as a Z value provides probabilities that can be summed. Z values allow normalization for comparisons of unrelated processes, especially useful for benchmarking.

Since a process FMEA is identifying risk associated with process application, the PFMEA can be a source of DMAIC projects. Those projects can cover all aspects of the projected process performance. The DMAIC approach can be used to increase throughput, increase capability, move the process mean, etc.. Since some KCs and CIs can be controlled through process application we can use DMAIC to make any adjustments needed to achieve the necessary process performance. Process and tool maintenance plans, safety issues, costs associated with process execution and inventory of parts and assets can also be impacted by DMAIC.

Root causes are at the base level of all causal analysis. A cause is considered a root cause when solving it can break or prevent the causal chain from being realized. Many problems are the result of multiple root causes as such there are multiple causal chains that must be broken or prevented. For example an automated drilling machine having problems accurately locating holes was found to be caused by multiple causal chains including those associated with the software program, the set up of the driller, the cleanliness of the product, the experience of the operator, the capability of the driller to stay on track and the maintenance plan for the driller. To solve this problem a solution set has to be developed based on the root causes that are actionable causes within each casual chain.

When the change will have a negative impact (e.g. Safety, cost, an adjacent process)

When the change in X would have a negative impact on safety, or when the cost of implementation of the change is prohibitive, when the change has a negative impact on another part of the system.