SPRING 2024

96
THE DISTRIBUTOR’S LINK
BRUNO MARBACHER LOCKING FEATURES TO PREVENT ROTATIONAL LOOSENING from page 28
Ribbed lock washers are made of hardened spring
steel. They ought not to be electro plated to prevent
hydrogen embitterment. They should be mechanically
plated, or zinc flake coated.
There are specific requirements that must be met
during assembly to assure these lock washers are doing
their job.
There are different types of ribbed lock washers,
based on their shapes they have different functions.
Ribbed Lock Washer
¤ The screw / nut was properly tightened.
Only then can the ribs penetrate both surfaces
and lock adequately. The ribs still lock after multiple
re-assemblies.
This lock washer is offered for screws of sizes M1.6
to M36.
Available materials: spring steel, stainless steel
phosphorus bronze, Inconel, etc.
Rip-Lock Washer One Sided Ridges
(French standard NFE 25-511)
This type of ribbed washer has an outside diameter,
which is about the same size as the bearing area
diameter of the screw and/or nut. It is ribbed on
both sides. Ribbed lock washers prevent spontaneous
loosening of the screws and/or nuts.
The washer is compressed. The ridges anchored into
both surfaces. A “ribbed lock washer” can considerably
increase friction. The fastened joint will become more
secure.
These locking elements are generally dished and thus
springy. They can hence compensate for relaxation.
The ridges are designed in such a way that they anchor
themselves into the clamped parts as well as the bolt
head’s bearing area thus resisting back-off.
The ribbed profile can only lock effectively if:
¤ The screw / nut is not too hard, i.e. max. property
class 10.9/10.
¤ The clamped part is not too hard (max 270 HV or 26
HRC).
This type of ribbed lock washer has a much larger
outside diameter. It covers large clearance holes and
elongated holes. The screw’s head or the nut always lies
on top of the ribbed side.
The bottom side of this washer has no ridges. The
large washer diameter produces enough friction on the
clamped part to prevent the washer from turning.
They are excellent locking elements. They are often
used in conveyer systems, pallet racks, elevator guiding
rails, etc.
This washer comes in spring steel with a hardness of
430-500 HV (43 – 49 HRC).
Ribbed washers may be used up to property class
10.9/10.
Ribbed lock washers are also available in stainless
steel. They are only strain-hardened and therefore not
very hard. Still, they provide a sufficient locking effect,
because of the high friction of stainless steel.
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