DIN 9021 is a standard reference number that is commonly used in the manufacturing industry. It is a specific type of washer that conforms to the standards set by the Deutsches Institut für Normung (DIN), which is the German Institute for Standardization. This particular washer, known as DIN 9021, is widely recognized for its flat, circular shape and large outer diameter. It is designed to distribute the load of a threaded fastener, such as a bolt or a screw, over a larger surface area, thereby preventing damage to the material being fastened. The DIN 9021 washer is often used in various applications, including construction, automotive, and machinery industries, where it plays a crucial role in ensuring the stability and integrity of the fastened components.