DIN 6921 Hex Flange Bolts
DIN 6921 Hex Flange Bolts are hex washer head bolts with external machine screw threads, a circular flange and smooth (non-serrated) bearing surface; the flange flares to a diameter that is larger than the hex top section. Clamping force is distributed over a larger area due to the integral head flange, which allows usage with irregular, misaligned and oversized holes. Flange bolts are often used with flange nuts. 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. 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. DIN 6921 Hex Flange Bolts are similar to ISO 4162, JIS B1189, ASME B18.2.3.4M and IFI 536.