The first picture is of an inexpensive 150W soldering iron with a fairly heavy tip, which is very useful for soldering coax connectors. One problem with the cheap iron, is that it has no temperature control. It just gets hotter and hotter if not used, until the barrel gets red hot.
The heavy tip retains heat because of it's mass, and the broad tip transfers it to a connector body very well.
The second photo shows what can happen it it is left plugged into a
power outlet, and somehow the rocker switch gets turned on
inadvertently.
This happened to me last week.
I had been in and out of my radio room many times while sorting and organizing 'stuff' in another space.
Apparently, I managed to flip the rocker switch ON.
Later, while
outside, I began smelling something like burning plastic or rubber.
After looking around, I guessed it must have been coming from a nearby
house.
As I went back into the radio room, I found the
odor quite strong, and discovered the counter under the soldering iron
was smoking, and a cardboard box which was on top of the iron had a
large scorched hole burned through the side, and a collection of small
hookup wire pieces had a lot of melted insulation.
I guess,
in the process of moving and sorting some of the piles on the bench, one
of parts trays wound up on the tip if the unused soldering iron.
Somehow later, I had inadvertently managed to turn ON the soldering
iron, and I am very grateful I was working quite close by.
Needless to say, I was VERY lucky to have found it when I did.
Please leave your soldering irons on some sort of a stand, when not in use; or if too large, unplug them.
Rod J