Linear Units

Drive Calculations
Screw Driven Units
Feed Force Formula [N]
Fx = m × g × µ
Acceleration Force Formula [N]
Fa = m × a
Power Formula [kW]
P =
Ma × nmax × 2 × 3,14
60 × 1000
Drive Moment Formulas [Nm]
Ma = Mload + Mtrans + Mrot + M idle
Mload =
Mtrans =
Mrot = jsp ×
Fx × p
2 × 3,14 ×1000
Fa × p
2 × 3,14 ×1000
2 × 3,14 × nmax × a × 2
Vmax × 60 × 1000
M idle = see table for unit in question
Fx = feed force [N]
m = total mass to be moved [kg] 1
g = acceleration due to gravity [m/s 2 ]
µ = friction factor specific for each unit
Fa = acceleration force [N]
m = mass to be operated [kg]
a = acceleration [m/s 2 ) 2
P = required power [kW]
Ma = required drive moment [Nm]
nmax = maximum required rotational speed [rpm]
Ma = required drive moment [Nm]
Mload = moment as a result of various loads [N]
Mtrans = translational acceleration moment [Nm]
Mrot = rotational acceleration moment [Nm]
M idle = carriage/rod idle torque [Nm] 3
Fx = feed force [N]
p = screw lead [mm]
Fa = maximum required acceleration force [N]
jsp = inertia of ball screw per meter [kgm 2 /m] 4
nmax = maximum required rotational speed [rpm]
a =maximum required acceleration [m/s 2 )
Vmax = maximum required linear speed [m/s]
1 The total mass is the mass of all masses to be moved (objects to
be moved, carriage(s)/rod, screw).
2 In vertical applications, the mass acceleration must be added to
the acceleration due to gravity g (9,81 m/s 2 ).
3 This value can be found in the carriage idle torque tables for each
196 www.danahermotion.com
unit.
4 This value can be found in the additional technical data tables.