On this page of our guide to BioShock Infinite you will find the first part of a detailed walkthrough of Chapter 25 - On the Factory. You will take part in many battles here and encounter a new type of Patriot.
Leave Chen Lin's workshop at approach a door located opposite the store. This passageway will soon become unlocked. Explore the first room before heading towards the factory.
Your job is to fight your way to a gate located on the other side of this area. You will have plenty of tears at your disposal and you'll also find a lot of salt and medical supplies. Wait for a Mechanized Patriot to join the battle before opening a tear that summons and automaton with rockets.
Once you've won explore the entire battlefield looking for supplies (you can also return to the Plaza of Zeal if you wish to). Approach the factory gate and deal with the remaining police forces.