How to Calculate Load Requirements of Lead Screws

Load Requirements of Lead Screws

In order to properly incorporate a lead screw into a design, load requirements must be taken into account. Maximum load values for the nuts are listed in the tables on the following pages. These numbers are based on the shear of the nuts and does not take shaft buckling into account (see Max. Column Load formula below). Wherever possible, nuts should be positioned so as to be put in tension, pulling the load. This eliminates the need for buckling considerations. Listed below are some helpful formulas to assist in proper lead screw selection.

Maximum Column Load Formula

Formula: (F) = K x C X 106 x d4 /D2
 K = End support factor
 .025 one end fixed, other free
 1.00 simple supports both ends
 2.00 one end fixed, one simple
 4.00 both ends fixed

 C = Material factor

Torque to Move a Load Formula

Formula: (T) = (F x L) / (2 x M x E)

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