Special Product Characteristics:

These special product characteristics are derived from the DFMEA. The special product characteristic derived from the DFMEA are marked on the component drawings in form of notations. You normally will not have a characteristics at the system level drawings. Factors influencing the declaration of special product characteristic are:

1) Government regulation.
2) Safety concern.
3) Severety of failure mode
4) Occurances of causes.

Each organization has its way of nominating special characteristics. Some use charts like the one below to mark a feature as special characteristic.

The general methodology based on the product manufactured or sercvice provided you can create your very own Chart.
 

 

Its a fact to be noted regarding the severity of 9 or 10 must be accompanied by a plan to reduce it below 9.

Others will depend on the type of product and its occurrences. All the design charecteristics and process charecteristics must be cascaded to the print. This is what can be used to measure the conformance to print for all products produced. The capability index will also be calculated on the charecteristics identified here on the print.

The method to calculate the CPk and PPk are explained seperately.