A washer is a common fastener fitting used to support, cushion, seal or distribute pressure between a bolt, nut or threaded rod and the workpiece. It is usually made of metal or plastic and has a ring shape. One of the main functions of the washer is to provide support and cushioning between the fastener and the workpiece to prevent the fastener from over pressing or damaging the workpiece during the fastening process. It balances the distribution of fastening forces and reduces the possibility of vibration and loosening. In addition, gaskets can be used to provide a sealing effect and prevent liquid or gas leakage. It can fill the gaps in the threads or joints to ensure the tightness of the tightening parts. There are many types of washers, including flat washers, spring washers, lock washers, etc. Flat washers are the most common type and have a simple round structure; Spring washer is elastic, can provide better cushioning and tightening force; The lock washer has a special structure that prevents the fastener from loosening under vibration or load. The selection of gaskets should be determined according to the specific application requirements, including the material, diameter, thickness of the gasket. The correct selection and use of gaskets can improve the reliability and sealing of fasteners and ensure the firmness of the connection.