STAR – Precision Ball Screw Assemblies

Permissible axial load on screw
F k (buckling load)
Example
Screw diameter = 63 mm,
lead = 10 mm,
Length lk = 2.4 m
End fixity II (fixed - supported)
According to the graph, the theoretically
permissible axial load is 360 kN.
A permissible axial load on the screw of
360 kN : 2 = 180 kN is achieved when
applying the safety factor 2. This therefore
lies above the maximum operating
load of F1 = 50 kN used in our
calculation example.
14
15
F k f Fk
F kzul
4
d2 2
lk F k
2
f Fk value End fixity
2.6 IV
10.2 III
20.4 II
40.6 I
4
10
(N)
(N)
F k = theoretically permissible axial
load on screw
F kzul = permissible axial load during
operation
f Fk = corrector value determined
by bearing
d 2 = root diameter (mm)
see Dimension Tables
l k = unsupported threaded
length (mm)
RE 83 301/12.99 97
lk
The permissible axial load on the screw F k
depends on the diameter of the screw, the
type of end fixity and the effective free
axial load on screw F k (kN)
F K
3000
2000
1000
800
600
500
400
300
200
100
90
80
70
60
50
40
30
20
10
9
8
7
6
5
4
3
2
1.0
0.9
0.8
0.7
0.6
0.5
125x10
125x20
100x10
100x20
80x10
80x20
63x10
63x20 - 63x40
50x5
50x10
50x20 - 50x40
40x5
40x10 - 40x20
40x40
32x5 - 32x10
32x20 - 32x32
25x5 - 25x10
25x25
20x5
20x20
16x5 - 16x10
16x16
12x5
8x2.5
0.1
0.2 0.3
(unsupported) length l k . A safety factor of
g ≥ 2 should be taken into consideration
when determining the permissible axial
load.
0.4 0.5 0.6 0.8 1
0.1 0.2 0.3 0.4 0.5 0.6 0.8 1 2 3 4 5 6 7 8 9 10
0.2 0.3 0.4 0.5 0.6 0.8 1
2 3 4 5 6 7 8 9 10
0.2 0.3 0.4 0.5 0.6 0.8 1
2 3 4 5 6 7 8 9 10
2 3 4 5 6 7 8 9 10
Length l k (m)