Hex Flange Bolt Head Weight Reduction Design Criteria

This report describes the design of hex flange head bolts, both inch and metric series, having heads reduced in volume to the least amount without degrading manufacturing or assembly requirements. Head dimensions were developed through a partly empirical equation involving all normal bolt strength test criteria, plus the added criteria that driving capacity must be no less than twice the torsional strength. The design was validated both in the laboratory and on the production line. An annual material saving of 2,000 tons resulted by replacing the standard hex flange bolts with the reduced head design in Ford Motor Company's production.