A square washer has a regular quadrilateral shape. Compared with round washers, its structure with four corners is a distinctive feature, providing unique advantages in specific situations. A hole is usually provided in the center of the square washer, compatible with common bolts and screws, to facilitate the installation of fasteners.
Carbon steel, stainless steel, copper, etc., are most frequently used. Square washers made of carbon steel are characterized by low cost, and after corresponding heat treatment (quenching, tempering), they gain enhanced strength and hardness but have relatively low corrosion resistance. Due to excellent corrosion resistance, stainless steel washers are often used in humid or chemically aggressive environments, such as the chemical industry, food processing, and marine construction. Copper washers have good electrical conductivity and non-magnetic properties, making them popular in electrical equipment and electronic devices.
Materials such as rubber, plastic, etc., are included. Rubber square washers have good elasticity, shock absorption, and insulation properties, and are often used in scenarios requiring damping, sealing, or insulation. For example, at the connection points of mechanical equipment with strong vibration, they effectively reduce vibration transmission and provide sealing against dust and moisture. Plastic square washers are lightweight, corrosion-resistant, and have good insulation properties, making them commonly used in light or electronic equipment where weight and insulation are important.