Tips do not tin after 2 uses. Actually the solder just bounces off the tip, even if I use a tip cleaner/tin that's a sign of a very cheap tip. I think you got what you pay for
I ordered these before realizing that it would be better if I only had a few soldering tips. Some of these I will probably never use. In the future I will only buy the attachments I need and not this set. However, the price was good and it's not like they take up too much space.
I was actually only interested in one of the nibs with more surface area and wasn't aware that most of them have quite thin nibs. In my experience, it's difficult to get enough power to melt solder with thinner tips, and you end up using higher temperatures than you want, reducing tip life. I would actually prefer a 2mm wedge instead of this set, but that's just my opinion. If you are looking for a variety of conical tips - they work, are of good quality and are reliable.