GMNA D144 PDF

GENERAL

This standard for Metric Oval 90° Countersunk Trim Head 6-Lobed Socket Tapping Screws of thread forming Types AB and B and thread cutting Types BG and BT conforms in all essentials, except head proportions and the driving provisions, with the American National Standard covering metric tapping screws. Basically, the smaller head proportions of the trim heads were derived by applying to the respective screw diameters the 1976 standard oval head diameters applicable to the next smaller screw size, and specifying a rounded edge.