Populate field with another fields value conditionally

[Bankshot]

I want to populate the serial number field with the id field value but only if the part type column does not contain certain values. Any suggestions 

[WillowMobileSys]

You would insert into the App Formula property and expression like:

IF (NOT(IN(Part Type], {"Value 1", "Value 2", "Value 3", "Value 4",...})),
    [ID Field],
    ""
)

See these articles for more on the expression functions used above

IN() 

NOT()

IF()