Specification Sheet

13
Nord-Lock “sp”
washers on painted
surface.
Nord-Lock “sp”
washers on soft metal.
Nord-Lock “sp”
washers on fibre
surface.
Nord-Lock “sp” (enlarged outer diameter) washers
Nord-Lock washers are available with an enlarged outer diameter,
referred to as “sp” washers. “sp” washers are designed for
use on large / slotted holes, painted / sensitive surfaces or soft
materials. Use Nord-Lock “sp” washers with flanged bolts or
nuts for optimum load distribution.
Ø inner regular = Ø inner “sp”
Ø outer regular < Ø outer “sp”
Uniform friction with Nord-Lock washers
When using Nord-Lock washers, sliding always occurs between the
upper washer and the bolt head / nut. At a given torque, the preload
will be the same, regardless of the contact material.
Nord-Lock provides customized torque guidelines for your application,
contact your nearest representative.
Untightening
Regular nut M8
on aluminium
without washer
Regular nut
M8 on steel
without
washer
Torque [Nm]
Tightening
Load [kN]
Regular nut M8 on
aluminium with
Nord-Lock washers
Regular nut M8
on steel with
Nord-Lock
washers
Torque [Nm]
Tightening
Untightening
By using “sp” washers, the load is distributed over a larger surface which
can be more gentle for sensitive surfaces. Please consult Nord-Lock to
find the optimal solution for your application.
A flanged nut and Nord-Lock “sp”
washers increase the load
supporting surface for
applications with slotted holes.
It is important to have control over the friction conditions in order to obtain the desired preload when tightening a joint.
When no washer is used under the fastener, the friction depends on
the contact surface. At a given torque, the obtained preload will vary
depending on the contact material.