METRIC TORQUE TIGHTENING GUIDE ?— > (.) rs STANDARD THREAD – ZINC PLATED – CLASS 8.8 STANDARD THREAD – ZINC PLATED – CLASS 10.9 Tightening Torque Tightening Torque DIAMETER FOOT-POUNDS NEWTON-METERS DIAMETER FOOT-POUNDS NEWTON-METERS x x * * X* KX KX KX NM EX FINE THREAD – ZINC PLATED – CLASS 8.8 FINE THREAD – ZINC PLATED – CLASS 10.9 Tightening Torque Tightening Torque DIAMETER FOOT-POUNDS NEWTON-METERS DIAMETER FOOT-POUNDS NEWTON-METERS x * xX Kk K K K X ~ w Due to the many interrelated variables that directly or indirectly affect the torque to clampload relationship, such as surface tex- ture, plating, lubrication, human error, etc., it is possible to experience as much as +25% deviation in preload (clampload) with the use of a torque wrench. These torque values represent an estimate of torque(a measurement of friction not tension) required to induce a given preload in non- critical applications only. In critical app- lications where greater control is desired this should be experimentally determined. TAP DRILL SIZE CHART Recommended Tap Drill Size For Approximately 75% Thread Formation THREAD TAP THREAD TAP THREAD TAP DIAMETER DRILL DIAMETER DRILL DIAMETER DRILL