Dongfeng EQ143 rear tire screw (active ring) production of screws of the material is mainly used in special steel mechanical properties to achieve 12.9. Factory invested a huge sum of money from Japan TOYO-RO purchased TXG surface blackening heat treatment furnace, full computer control, to ensure the stability of heat treatment, the screw surface as a. Factory has a complete material mechanical performance test, the factory of each batch of screw sampling, archiving, ensuring the quality of stability and traceability.