Hexagonal flange bolts have a protruding flange face under the head, similar to the role of a washer. Since the flange surface distributes the pressure and reduces the damage of the bolt head to the connection area, it can be fixed effectively without additional washers. It is mostly used in places with more stringent structural requirements, such as automobiles and mechanical equipment. Its flange face design allows it to provide better tightening effect when connecting and reduces damage to the connecting parts.
Reference standards:DIN6921,GB5787,JISB1189.