It has a third attack where it lunges its neck straight out. It is very easy to dodge, but it has much longer range than its spin attack.

To force their side panels to open use your vertical attacks. For instance, on keyboard and mouse it's Right Mouse Button. To kill the one in Resolve Biolabs (the one standing on acid) get Elite Hazard Legs (https://thesurge.wiki.fextralife.com/El ... d+Leg+Gear) from enemies on the next level, i.e. the UTOPIA Project area where you find Dr. Gene Barett.

Rush to it, you will be minced by its weapon if you are too far. Just circle it and wait for the side panel to open. Don't stay too near or it will sit on you.( also don't keep attacking carelessly, you will be Flattened) You can easily destroy some back armor to out balance it and force it to use smaller replacement legs. You can damage them and cause them to spark. I don't know if that encourages it to reveal its weakspot. Save stamina, unleash when it's sides open.

A 100% safe method is to just kill everything near the smelter bot, then get just close enough to lock on from a spot that it cant hit you from, then spend the next 15-20 minutes continuously firing the free drone laser shot until its dead.

Here’s a sound thing for anyone who’s having trouble keeping track

1 short beep: lunge
1 short 1 long: slam
2 short beeps: Stomp
2 long beeps: Around the world spin. Will kill in one hit if not at full health

I killed the first one in Abandoned Production after seeing the 2 in the second level to see if I could, and when I went back to the second level there was only 1, and a Shining Coin just chilling on the ground.