Hitachi WH 10DL Technical Data And Service Manualice Manual page 10

(2) Diameter of thread and appropriate tightening torque
Generally speaking, the appropriate tightening torque for a screw can be determined by the strength
grade of the screw or the material tightened. Following tables list data relative to the strength grade of
various screws and the appropriate tightening torque. For reference, appropriate tightening torque is
calculated with the following formula.
T = k d p
• •
T: Appropriate tightening torque (kgf
d: Nominal diameter of thread (mm)
p: Recommended axial tightening force to be applied to the screw (kgf)
p = Rated axial stress (kgf/mm
k: Torque coefficient (0.17)
Strength grade and rated axial stress of thread
•
Strength grade
Rated axial stress
(kgf/mm 2 )
Material
Heat treatment
Diameter and effective sectional area of thread
•
Kind of thread M5 x 0.8 mm
x pitch
Effective
sectional area of
thread (mm 2 )
Diameter of thread and appropriate tightening torque
•
cm)
•
2 ) x 0.8 x Effective sectional area of thread (mm
4.8
29.1
Mild steel
Not processed
M6 x 1 mm M8 x 1.25 mm
(3/16") (1/4") (5/16")
14.2 20.1 36.6
-7-
6.8 8.8
43.7 58.2
Alloy steel including Ni, Mn, Cr, etc.
Processed: Hard material
M10 x 1.5 mm M12 x 1.75 mm
(3/18") (15/32")
58.0 84.3
2 )
12.9
95
M14 x 2 mm M16 x 2 mm
(9/16") (5/8")
115 157