anyone ever heard this noise?

[koolZ71]

yesterday i was breaking...it only did it one time but scared the shizt outta me....a super super loud screaching, scaping sound...and no it wasnt the sensor on the pad..lately i have noticed tons of brake dust on my front rims...im just trying to figure out what the heck that noise was

[AMRAAM4]

I don't know all the inner workings of the brakes so someone correct me if the term is wrong, but could it possibly be the pad has worn down far enough for the piston/caliper to be hitting bare metal of the rotor?

[Blackrider]

It wouldent bee the piston but the Backing of the pad is Metel and could be Chewing up the roter. If thats the case feel the back side of the roter and feel if it is Rough if it is then you have destroyed the roter

[Rogue9]

On the brake caliper bracket, topside above the top guide rail for the outside pad there's a little nub of metal slag (I think) that might be rubbing.
are there any scratch marks on the rotors?
I don't know why this little nub is rubbing on my rotors since they never did before so I haven't figured out any other solution than to file it down.