经典图书 Doesitmatterwhetheryoutightentheboltheadorthenut?Normallyitwillnotmatterwhethertheboltheadorthenutistorqued.Thisassumesthattheboltheadandnutfaceareofthesamediameterandthethecontactsurfacesarethesame(givingthesamecoefficientoffriction).Iftheyarenotthenitdoesmatter.
Saythenutwasflangedandtheboltheadwasnot.Ifthetighteningtorquewasdeterminedassumingthatthenutwastobetightenedtheniftheboltheadwassubsequentlytightenedinsteadthentheboltcouldbeoverloaded.Typically50%ofthetorqueisusedtoovercomefrictionunderthetighteningsurface.Henceasmallerfrictionradiuswillresultinmoretorquegoingintothethreadoftheboltandhencebeingovertightened.
Ifthereversewastrue-thetorquedeterminedassumingthattheboltheadwastobetightenedthenifthenutwassubsequentlytightened-theboltwouldbeundertightened. |