The Junker(1975)

The Junker, whose base of operations is beneath a junk yard in Good Haven, creates robots that "eat" metal. The Junker's robots consume cars, bridges and other structures. The Mighty Heroes attempt to contain the damage and eventually follow the robots back to the Junker's lair. But the villain traps the heroes inside a metal container, which he then crushes. Now, the Junker sicks his robots, saying they're free to consumer a "hero sandwich." But the heroes prevail, destroying the robots and capturing the Junker.