Produced by THE WORLDFOLIONISSEI supplies you with technology,
not the locking bolt itself
n Rolling a low cost, anti-loosening bolt “PLBv2” at last! This practical and effective bolt does not rely on friction.

TOSHINAKA SHINBUTSU,
President, NISSEI

We might think there are no technical improvements left to be made on a bolt, but
let’s think again: what about the problem ofloosening? It is a fact of mechanical life thatbolts loosen. Many techniques for keeping
bolts tight have appeared. From the point ofview of practical usage, cost effectiveness,and the ability to truly prevent loosening,making better bolts is an old but new problem. Nissei invites you to look at their freshsolution, PLBv2. PLBv2 (Perfect Lock Bolt,version 2) relies on double nuts and multiple
threads rolled onto a single shaft.
For fasteners such as bolts, loosening is
the enemy. The need for periodic tightening
and problems arising when bolts need to be
replaced or re-used are common. In the battle against loosening, many solutions havebeen attempted—all, until now, have been
mediocre. Relying on friction to prevent
bolts from loosening is not good enough. Amechanical solution built into the structureof the bolts is what is needed.
Principle and Features of PLBv2
Here is one mechanical method to protect
against loosening. Roll the lead of eachbolt with two different threads, then add
one nut to follow each thread. Because thelead that the inner nut follows is longer
than the one for the outer nut, when vibration inevitably makes the nuts start torotate loose, the inner nut will be blocked
by the outer nut. This is because the leadfollowed by the outer nut is more closelypacked, and so the outer nut must rotate
more slowly. This is mechanical blocking.

Manufacturing method
A major value of PLBv2, above and beHow to mass produce bolts with two sepa- yond its anti-loosening properties, is practirate and distinct threads? It cannot be done cality in actual use. By tightening the outerreliably by cutting threads into the bolt nut, the inner nut is also tightened. Bothshaft, but it can be done with thread rolling. bolts, one action. With ordinary double nuts,Nissei, an innovative maker of rolling ma- each nut has to be tightened individually.
chinery located in Yamanashi Prefecture in With PLBv2, the inner nut follows the outer
Japan, has tackled this problem to produce nut naturally. It is like having to fasten only
uniform and reliable bolts that cannot be one nut instead of two. No PLBv2-specificloosened by normal
tools are required,vibration: PLBv2.
ordinary tools doMachines thatthe job. Ease andcould make diespracticality incapable of rollingusage are addiMultiple
Singlea complicated pattional advantages
threads
threadnut
nuttern were not readof PLBv2.
ily available when
The process
we started ourof rolling bolts
Perfect Lock Bolt
with thread rollBig advancement Small advancement
PLBv2 bolt combines by one rotation
by one rotation
project. In 2018,
ing machines isa single thread andwe c o m p l e t e dadvantageous tomultiple threads.
round dies, then inbolt makers. In
2019 flat dies, deother, more ordiveloping new technary processes,niques one after
after cold forging, heat treatthe other. We enment processing
visioned planetaryis recommended.
dies as the means
PLBv2 bolt combines a single threadto this end. All in all, and multiple threads. Threading of PLBv2 The same processes are applied
it has taken 15 years requires specialty dies made by NISSEI.
to reach the level at The dies can be used on an ordinary thread to PLBv2 withwhich our machines rolling machine. The dies can roll PLBv2 in the same system.
There is no need to
can roll two kinds of one action.
buy new systems
threads—simultawhen you have the license. The threads
neously—on one anti-loosening bolt.
can be rolled simultaneously on existing
thread rolling machines, provided they are
Can be rolled with your company’sequipped with PLBv2-specific dies madeexisting equipment
The anti-loosening bolt that Nissei has de- by Nissei. “Being able to roll these bolts
veloped and named PLBv2 has been tested on machines already in place is a big adand conforms to international standard vantage,” says Shuichi Amano, chief engiISO16130. For the specified vibration cri- neer/engineering director at Nissei. “It’s aterion relative residual clamp force of 2000 competitive cost advantage to get a better
cycles, other companies’ products received bolt from existing equipment.”a rating of “acceptable loss of clamp force”,
which in ISO16130 terms means they perform adequately from 40% to, at best,
85% of the time.. PLBv2 is rated ISO16130
www.nisseiweb.co.jp/e/index.php“Good self-locking behavior”, meaning percontact: plb_bolt@nisseiweb.co.jp
formance is good 93% of the time.