Design, development and manufacture any kind of washers ...
Toothed lock washers or star washers. Directional teeth or serrated edges bite into fastener head/workpiece to prevent loosening. Most common standards are DIN 6797 and DIN 6798. Tab washers: It a washer that works by having a side tab that can be bent into place against a nut to lock it. Some standards are: DIN 432, DIN 463, DIN 93, and DIN 462.