JDF F436 Hardened Structural Washer

The product in the image is a high-strength structural washer manufactured by Ningbo Jinding Fastening Piece Co., Ltd., a major fastener manufacturer based in China. The marking 'JDF' on the washer is the registered trademark and manufacturer's identification symbol for the company, while 'F436' refers to the ASTM F436 standard. This specific standard covers hardened carbon steel and weathering steel washers intended for use with high-strength structural bolts, such as those meeting ASTM A325 or A490 specifications.

Originally founded in the Zhenhai District of Ningbo, the brand has become a significant player in the global fastener market, exporting structural hardware to markets in North America, Europe, and Australia. These washers are through-hardened or carburized to provide the necessary strength and stress distribution required for critical infrastructure, such as bridges, buildings, and industrial machinery.

As of 2026, the brand continues to be owned and operated by Ningbo Jinding Fastening Piece Co., Ltd., which maintains extensive manufacturing facilities in Zhejiang Province. The company manages the entire production cycle, from raw material processing and cold forging to heat treatment and surface finishing, ensuring compliance with international quality standards like ISO 9001.