- For the machine with minor kinetic friction, it can be ignored by leaving some margin during selecting a system. -If the kinetic friction is impossible to known until the machine is well assembled, upgrade the margin. ((15.16+T f ) 2 x 0.1)+ ((T f ) 2 x 2) + ((-15.16+T f ) 2 x0.1) The margin in continuous duty zone: A Servo Selection Example(4) - The kinetic friction should be known in advance for the machine moving with high kinetic friction. Min {5.9, 5.5} = 5.5 (N-m) 0.1 +2+ 0.1 T rated = 7.16 (N-m) = z The Margin for Kinetic Friction T f = 5.5 (N-m) The margin in intermittent zone: T f_margin_I = 21.5 – 15.6 = 5.9 (N-m) 15.6 (212%)