The above is another way of illustrating how each document ‘feeds’ another. This is quite clear when you understand the requirements of each document.
It should be noted here that while there is a reference to a characteristics matrix, some companies put ‘critical’ (or ‘special’ characteristics, or whatever your terminology is) on their drawing or somewhere other than a ‘stand-alone’ characteristics matrix. This is an example of ‘meeting the intent’. You can start all of your documents at the same time, technically, but ‘critical path’ comes into play.
From this illustration we can see several factors.
Determining / defining ‘critical’ or ‘special’ characteristics (customer and internal) must be started early. If you do not know what these are you cannot complete either of your FMEAs. If you do not complete your design FMEA you cannot complete your process FMEA as sometimes your design FMEA will contain inputs to your process FMEA. You cannot complete your process FMEA until your process flow diagram is complete If you cannot complete your process FMEA, you cannot complete your process control plan. In the same vein, you cannot complete your characteristics matrix until you know your customer requirements.
Typical Automotive Trilogy Development
Process Flow Diagram
(Includes ALL Processes)
(On ALL Processes)
Process Control Plan
(Critical Processes from FMEA)
(On Intended Use)
Some Elements may be Included On
& Characteristic Control Issues
& Failure Effects Issues
(drawing, RFQ, etc.),
Your company’s internal design / process requirements