Global Service Information No.143
Jan.25.2011
1. Service Tip
The deteriorate of taper accuracy according to the effect of
fastening torque of pull-stud bolt
If fasten pull-stud bolt over proper fastening torque that tooling maker is announcing,
small diameter of taper expands and only contact to small diameter as the diagram indicated below.
As the result, contacting area of taper becomes less and dynamic and static rigidity become diminished.
Another also affect run-out accuracy.
If fastening torque is over 40 N･m, have a known that dynamic and static rigidity become diminished a lot.
About each tooling, control the proper fastening torque as indicated below.
Proper fastening torque that tooling maker is announcing
BIG : 25 - 30 [N･m]
NIKKEN : 20 - 25 [N･m]
NT TOOL : 8 - 12 [N･m]
Apply a glue.
There is a difference of fastening torque between the each maker
because there is a difference of expanding amount of small diameter.
Check proper fastening torque other tooling maker.
small
diameter
big
diameter
Taper face of tooling is changed by fastening torque of pull-stud bolt as shown below.
low contact
high contact
swelling
Fastening torque
high
proper
torque
Enlarge picture
of taper face of tooling
low
Friction and gloss are generated
because contact with
spindle taper is too much.
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A precedent of small diameter