Steps for designing power screw:

a) Select type of thread for screw.

b) Enter axial load acting on screw in Newton and effective length of screw in mm for buckling load calculation.

c) Enter required factor of safety on design stresses.

d) Enter design Yield stress and shear stress of screw material in N/mm^2.

For example:

Yield strength of hardened and tempered C-45 is about 360 N/mm^2 and Shear stress is about 0.57 x Yield strength = 205.2 N/mm^2.

e) Enter Young's Modulus of screw material in N/mm^2 .

f) Enter design Yield strength, compression strength, shear strength and bearing strength of nut material in N/mm^2.



g) Enter number of start on screw and coefficient of friction between nut and screw. 

Refer table for some example


h) Minor diameter (dc) will be calculated based on above data in mm.

i) Enter next standard minor diameter and corresponding pitch from the table below in mm.

j) Results will be generated as per data entered above. In case of design failure, increase core diameter of screw.


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