Electronic – Soldering iron tip grinding

This looks to me like a combination of too high heat and crappy tip coating. Unfortunately this is common with unregulated soldering irons. They usually get much hotter than a regulated iron because they always put out the same power, and that power has to be enough to solder against a ground plane or something else that acts like a heat sink. A regulated iron would just crank up the power when needed, but a unregulated iron is stuck with a fixed power, so gets too hot, sometimes way too hot, when just sitting in the holder. I've seen a unregulated 25W soldering iron get hot enough to visibly glow in a dark room.

The excessive heat can not only damage whatever you're soldering, but it speeds up the oxidation reaction that eventually ruins tips. Solder oxidizes fairly quickly, even at normal soldering temperatures. You may have tinned the tip regularly, but I'm sure that didn't last long. Then the tip coating starts to oxidize. Once that's worn off, you're left with copper. Copper is actually eaten away by soldering itself. It migrates into the tin/lead mix, which is one reason solder works so well on copper.

People that buy unregulated irons are shopping on immediate price, so manufacturers make them as cheap as possible. That probably includes the cheapest possible tip coating that looks good out of the box.

So in short, it looks like you got what you paid for.

Leave the solder on the tip.

The tip of most soldering irons are iron plated copper.

As such, if the tip is exposed to the atmosphere, it will rust.

Now, typically, there is a layer of solder which coats the tip. However, if you wipe the tip off, the solder coating remaining is very thin, and can oxidize through, allowing damage to the actual iron plating of the tip. Leaving a heavy coating of solder on the tip (e.g. the "blob" the manual describes) is indeed a good way to preserve tip life.
However, the great majority of tip wear occurs when the iron is hot, as the increased temperature dramatically increases the rate at which the tip will oxidize and react with the solder, so it's not absolutely critical you leave solder on the iron tip when you turn it off. It's a good idea, but it's not absolutely vital.

It's also worth noting that the solder blob will probably protect the tip from light mechanical damage during storage as well.

During normal use, the mechanism that wears through the tip plating is different. Basically, over time, the iron plating actually dissolves away into the solder. However, there's not much you can do about this, short of using a fancy soldering system that reduces the iron temperature when it's in the stand, which reduces the rate at which the iron dissolves away (at least when it's in the stand).

Basically, iron tips don't last forever.

During normal use, you should never wipe the tip before placing the iron back in the stand. You should always wipe it after removing it from the stand, before actually soldering something.

• Remove iron from soldering iron stand.
• Wipe tip on sponge.
• Solder something
• Place iron back in stand with solder left on tip.
• Repeat.