Introduction
SEMS Screws are combinations of a screw, a spring washer and a flat washer, which are fastened together by rubbing the teeth. There are also many types, including split type, gasket type, etc. These screws with corresponding washers are very convenient to use, and do not need to manually allocate spring flat washers, which saves time, can make the production line easy to operate and improve work efficiency.
http://www.junly-hardware.com/fastener-parts/