Techno Linear Motion Catalog32Technical InformationTo calculate torque to accelerate system:wpqT= 2 x IOx ––– x ––––– x –––t1803820 3.1416 x 1.8T= 2 x 18.25 x ––––– x –––––––––––– x –––0.5 180T= 364 oz•inTo calculate torque needed to slide the weight, assume a frictional force of 6 oz:T(friction)= 6 x 1.5 = 9 oz •inTotal torque required:364 oz •in+9 oz •in––––––––––––––––––––––––––––––––––––––––––=373 oz •inLead Screw Formulas and Sample CalculationsLinear Speed (ipm)steps/ secondLinear Speed = –––––––––––––––– x 60 x –––steps / revolutionwhere:p= lead screw pitch in threads per inchAxial Force(lb)2pForce = –––– x T x p x eff.16where:T= torque (oz •in)p= lead screw pitch in threads per incheff. = efficiency expressed as a decimal: 90% = 0.90Note:Ball screws are generally 85% to 95% efficient. Acme lead screw efficiency is generally 35% to45%, but can be as high as 85%.A.Calculating the torque required to accelerate a massmoving horizontally and driven by a ball bearing leadscrew and nut. The total torque the motor must provideincludes the torque required to:a. accelerate the weightb. accelerate the lead screwc. accelerate the motor rotord. overcome the frictional forceTo calculate the rotational equivalent of weight w :11 2I(eq)= wx –––– x (–––)p2Motorw2412412p1p
