I've been working on a project using carbon fiber filled PLA. I knew standard brass nozzles would wear faster printing CF, but I had no idea how fast. (I just figured I'd replace my nozzle after the project is finished.) Well after printing about 1.5kg of carbon fiber PLA, I noticed my prints were getting a little ragged and also that my table height was needing re-calibrating. I finally looked at the nozzle closely and realized that the orifice diameter had enlarged from 0.5mm to almost 1mm, and also that about 0.4mm had worn off the tip of the nozzle! This explained my increased blobbing, poor surface finish and the need to re-calibrate the Z axis. I had no idea the nozzle would wear so fast. CF is fun to print with (it has a nice mat black finish that really hides the print lines) but I'll have to invest in hardened nozzles if I keep it up.