Hello,
I damaged again my soldering iron tip and don't know why. It looks like this:
Can you tell me, why this is happening? Is the iron getting too hot? Or do I have to store in a special way? I stored it in the soldering iron holder by room temperature after using it.
Thank you!
Way too much heat, it’s badly oxidized. It looks like an inexpensive tip with no plating, other than for perhaps the tip for 2mm or so.
What brand iron?
Edit: I don’t like such small tips, there is no thermal mass from which to transfer heat. The smaller the tip, the more likely you have to overheat them to get a decent solder joint. If you are only soldering small smd’s, maybe it will be okay but as soon as you need to solder a thru-hole lead, you’ll never get enough to heat out of such a small tip.
I'm in no way an expert, but I do have decades of soldering experience and have similar problems, in the past. My cases may not match your case, so my "solutions" may or may not apply, but here's a list:
And now, for a little chemistry/physics: When you solder something, what is actually happening is, the solder is actually dissolving some of the metal on the surfaces you are soldering. This is what allows the solder to create a good electrical bond, and even mechanical. The flux cleans oxides off the surface of the metal [that you are soldering to] so the molten alloy can get good, clear access to this metal, and properly dissolve it, so the bond is good.
The same sort of thing happens on the soldering iron tip. And, the better soldering iron tips employ metals that stand up to this well, and thus provide a long service period.
Tip [pun kinda intended 
]: When you're done soldering, don't wipe the tip off! Leave it coated with solder. That will keep it tinned and prevent the tip from oxidizing. It also will help prevent the accumulation of carbon. BTW: I used to have this problem a lot, until I bought a soldering station from a different manufacturer. I've gone over a year with none of that nonsense! I hesitate to offer a recommendation, though, 'cuz, in other ways it's lacking. When I get my hands of more funds, I plan to purchase a higher-end system. Also, I don't think the model I have is available anymore...but here it is: X-Tronic™ Model # 3020. I chose it because of the availability of a flat bottom bevel tip, that I like to use for hand soldering SMD parts.
TIP2: Throw out that sponge that comes with most soldering irons/stations. I mean, think about it: Hot iron shoved into water!?! Talk about shocking the hell out of the thing! Instead, invest in a Metal Wool Soldering Tip Cleaner:
Hakko makes some inexpensive but nice soldering stations with good tips and temp control. I have destroyed a lot of tips until I went to the ones with heat control.
I like the wet sponge sometimes. It helps to remove some residue from burning on the tips.
Thank you very much for your tips! To my used products. I tried to use high quality products from ERSA.
The soldering iron:
Ersa Lötkolben Multitip C 25 25W 230V 0920BD
The Tip:
ERSA Lötspitze 0172BD Ersadur bleistiftspitz zu Multitip C25
Are this products not good?
You need to practice, until it becomes habit, to clean the tip before EACH soldering action.
Paul
Far too hot, once a bit gets that oxidized its hard to repair it.
Firstly you need an iron that has temperature control, preferably with a dial to set the temperature,
anything less will just be horrid and difficult to use.
Soldering iron bits are made of copper, with a coating of iron on the tip. The iron coating is
insoluable in molten solder and prevents the bit dissolving away (bare copper dissolves in a few hours
of use).
You have to protect the iron coating by never using abrasives or hard metal tools on it - once the coating
is damaged the bit will dissolve away...
This means if it gets oxidized its very hard to remove the oxide without risking the iron plating.
Never leave an iron switched on and unused, the bit will oxidize.
If you see very cheap bits, they may be uncoated, or not made of copper. Avoid like the plague!!
450C is much too hot.
This is a great soldering iron. I have the older model.
This PDF will give you the correct temperature range for each type solder you may be using: Solder melting temps
Paul
Irons have to be the right amount above melting point for good rapid melting and solder flow,
enabling a quick and reliable joint. Too cold is just as bad as too hot - experience and practice
help know when its right.
As others have indicated, There seems to be a slight problem with this iron. The 15W version is specified as 350 °C while the 25W version is specified as 450 °C. These irons are supposed to have a degree of temperature control by the PTC element but this is simply not the same as an actual temperature controlled (electronic or Curie Point) iron.
The 450 °C is simply too hot. These are apparently designed as production line irons, to be used continuously, not to sit on your bench while you move components around.
In "the old days", the trick was to make a power board with a switch and a lamp in series with the socket for the iron; the switch would short out the lamp to supply full power (in advance) when you needed to use the iron, the lamp in series would keep it hot at a lower temperature. This is still a plausible approach with a footswitch but really, you need a proper temperature-controlled iron.
In the meantime, buy a new tip and turn the iron on only when you need to solder a number of connections.
Something others have not mentioned - never, just never use the tip for melting plastic.
MarkT:
You have to protect the iron coating by never using abrasives or hard metal tools on it - once the coating
is damaged the bit will dissolve away...
Which reminds me, I forgot to mention that using fine grit sandpaper on your soldering iron tip should be a last measure, and is remedy for carbon build up. And only sand away the carbon. Avoid sanding the metal on the tip. This should be a rare action, and with proper care of the tip, it should never be needed.
Forget the sandpaper or anything similar, there are products that do not destroy the plating on an oxidized tip. These are used on a cold, not hot, tip.
Clean, heat and coat with solder or dip in tip tinner.
NEVER use sandpaper on coated tips.
Just tin the tip with normal resin-cored solder, and clean on a damp solder sponge or goldilocks (SS wool).
Repeat several times as needed.
Prevent by setting the right temp, and never use the tip to melt plastics.
Leo..
When I finish work and unplug my irons, I keep the tips wet with molten solder until they get cool enough for the solder to freeze, then they have a protective solder coating until next use.
It's over heated and generally for new soldering iron tips, you'd better do the tinning of the tip before you start to formally use it, that helps to extend the service of life of the soldering tip. Here are some reference of soldering:
It would also be a good option to get the cleaning sponge (actually it's slices of metal made into sponge form), which you can dip your soldering tip into to get rid of the residue of rosin & solder to keep the tip nice & clean.
Last summer I forgot to disconnect my solder iron. 4 weeks later I discovered that it was still on. The tip was damaged and needed to be replaced.
It is not the first time I forget to turn it off. I finally solved it by using a Nano, a PIR sensor and a relay (+ other parts) to make a SIC - Solder Iron Controller.
I turn it on by pushing a button. Then a LED display start counting down to when the iron is hot enough (estimated time). As long as there are movements around, the iron stay on. If no movements, then it is turned off after 30 minutes.
No matter how much movements there are, the iron will always be turned off after 4 hours.
That's a clever approach, but perhaps use 5-10 minutes rather than 30 minutes - enough time to boil a
kettle or whatever...
MarkT:
That's a clever approach, but perhaps use 5-10 minutes rather than 30 minutes - enough time to boil a
kettle or whatever...
It's easy to upgrade the "firmware" for this unit 
