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3. Production Process Characterization
3.1. Introduction to Production Process Characterization


What is PPC?

In PPC, we build data-based models Process characterization is an activity in which we:
  • identify the key inputs and outputs of a process
  • collect data on their behavior over the entire operating range
  • estimate the steady-state behavior at optimal operating conditions
  • and build models describing the parameter relationships across the operating range
The result of this activity is a set of mathematical process models that we can use to monitor and improve the process.
This is a three-step process This activity is typically a three-step process.
The Screening Step
In this phase we identify all possible significant process inputs and outputs and conduct a series of screening experiments in order to reduce that list to the key inputs and outputs. These experiments will also allow us to develop initial models of the relationships between those inputs and outputs.
The Mapping Step
In this step we map the behavior of the key outputs over their expected operating ranges. We do this through a series of more detailed experiments called Response Surface experiments.
The Passive Step
In this step we allow the process to run at nominal conditions and estimate the process stability and capability.
Not all of the steps need to be performed The first two steps are only needed for new processes or when the process has undergone some significant engineering change.  There are, however, many times throughout the life of a process when the third step is needed. Examples might be: initial process qualification, control chart development, after minor process adjustments, after schedule equipment maintenance, etc. 
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