I understand what you are saying but I'd rephrase it like this. Everytime I loosen or tighten the locks on adjustable dumbbells small iron bits fall off. The iron bits are very sharp and I've cut my hands on them many times already.

Your picture actually looks like bits and long thin strips of metal

You can refer to metal bits that fall or chip off as “swarf” or chıppings, flakes, shards. If they are sharp and pointed like broken glass “shards” is the best answer. İf they look like the curly bits that come off a lathe “swarf” is the correct word. Chips = little bits lıke tiny stones. Flakes if they look like thın slices of curly cheese from a grater.

Can u help me learning english?