KIC

The Process Window site Index for a complete set of profile statistics is calculated as the worst case (highest number) in the set of statistics. For example: if you run a profile with three thermocouples, and four profile statistics are logged for each thermocouple, then there will be a set of twelve statistics for that profile. The PWI will be the worst case (highest number expressed as a percentage) in that set of profile statistics.

The Process Window Index is calculated using a formula that includes all statistics for all thermocouples. The formula for the PWI is calculated as follows:

i=1 to N (number of thermocouples)
j=1 to M (number of statistics per thermocouple)
measured_value[i,j]=the [i,j]th statistic's value
average_limits[i,j]=the average of the [i,j]th statistic's high and low limits
range[i,j]=the [i,j]th statistic's high limit minus the low limit

Thus, the PWI is the worst case profile statistic (Maximum, or highest percentage of the process window used), and all other values are less.

Benefits of Ranking with PWI