1. Head height. The height of the head is measured parallel to the bolt axis, from the top surface of the head to the height of the supporting surface (for flat supporting surface head type); or from the top surface of the head to the cone supporting surface of the head and the square neck plane or without thread The height of the intersection point of the rod diameter (applicable to the countersunk head type).
2. Fillet under the head. All bolts with a flat bearing surface should have a certain rounded corner at the joint between the head and the rod. The radius of the small fillet is equal to 1/2 of the maximum value specified in the corresponding dimension table. The fillet radius should not exceed the value specified in the corresponding dimension table, except for bolts made of non-ferrous metals and corrosion-resistant steel. For bolts made of these two materials, the fillet radius value under the head should be negotiated between the supplier and the buyer.
3. The circumference of the head. The head of the weld nut is generally unprocessed or not trimmed. Therefore, the circumference of the head is allowed to have slight irregularities, and the edge can be round or flat.
