You can sort records to make a record with the greatest (most recent) date the first record. This can identify the factory.
Once you have that record, there is more than one way to get to the result that you want:
1) You can use Go to Related Records to pull up all records related to that Factory, then use Constrain Found set to limit the found set to entries dated with a date in the last 30 days. See this thread for examples of scripted finds that includes computed date range examples: Scripted Find Examples. Just use Constrain Found Set in place of Perform Find.
2) You can set up a relationship that matches on a computed date range to match to those self same records. This makes it possible to list the related records in a portal or GTRR can use this relationship to pull up a found set of the same.
I didn't see this before.