HYDROK – Safety
Coefficients of
friction
For workpieces of a material other than steel, the val-
ues shown must be multiplied by the correction val-
ues specified below.
For hardened steel as the material, the values of the
smooth jaws always apply for ground workpiece sur-
faces.
NOTE
Clamping of hardened materials or materials
with extremely high strength values
[R
m
> 1300 N/mm
2
] is only permitted with
smooth clamping heads!
Other clamping head designs can be damaged
and lose their capacity of achieving higher co-
efficients of friction with soft materials.
Workpiece surface
Jaw clamping surface
Smooth
clamping head
Clamping head
with longitu-
dinal and trans-
verse serration
Clamping head
with Z-serration
Clamping head
with F-serration
Finely finished,
ground
μ
t
=
0,06
μ
a
=
0,08
μ
t
=
0,07
μ
a
=
0,09
μ
t
=
0,15
μ
a
=
0,20
μ
t
=
0,17
μ
a
=
0,22
Finished to
roughed
μ
t
=
0,10
μ
a
=
0,13
μ
t
=
0,11
μ
a
=
0,15
μ
t
=
0,18
μ
a
=
0,25
μ
t
=
0,23
μ
a
=
0,28
Rough machined
or unmachined
μ
t
=
0,14
μ
a
=
0,16
μ
t
=
0,16
μ
a
=
0,18
μ
t
=
0,20
μ
a
=
0,28
μ
t
=
0,25
μ
a
=
0,30
Material correction
values
Aluminum alloys
=
0,97
Ms 58
=
0,92
GG-18
=
0,80
Table 5: Friction coefficient for steel workpieces
28
Order h49 7144.907-333
