Every grinder eventually needs to be cleaned eventually. If you have an espresso grinder, a Baratza coffee grinder or even a hand-held Hario Skerton grinder, you need to clean it eventually. 

Just put a few pellets in the grinder, run them through and follow it up with some beans and you're ready to go. They're 100% food safe and can be used on pretty much any coffee grinder - stand alone or integrated - on the market.