Clamping force is distributed over a larger area due to the integral head flange, which allows usage with irregular, misaligned and oversized holes. Steel Class 8.8 and 10.9 and stainless steel are available. For steel, zinc plated and plain finish (no surface treatment to inhibit rust) are common. Plain finish steel and stainless steel thread tolerance is 6g and plated steel is 6h; right-hand threads are standard.

DIN6921 hexagon flange bolt also called hex flange screws, some are fully threaded while those that are partially threaded have a minimum threaded length that varies with bolt diameter and bolt length. Length is measured from under the head to the tip.

If vibration occurs after they are installed, they need to be re-tightened; the flange has a thin part, which can be slightly deformed and locked more firmly. In addition, if it goes up to the hole, the ordinary bolt can't use the tool. DIN6921 hexagon Flange Bolt head is small, and the flange plate below also plays a tightening role, but it can be up to the hole with a special tool. , about the same principle as the hexagon socket bolt. Then there is the flange top flat pad, which is safer on softer, non-wear-resistant materials and will not cause perforation.

http://www.rock-hardware.com/