MOBIO booth No. : North facility 2nd floor 81,82


Product line

Anti-loosening fastener

Hardlock Nut

Hardlock Bearing Nut, Hardlock Set Screw


Katsuhiko Wakabayashi

Description of business

Hardlock manufactures and sells nuts that do not loosen and plays a vital role in building safety despite being tucked in locations invisible to the public eye. Working from the corporate philosophy “safety is power,” Hardlock has established a record of providing safety and security to critical locations in Japan and abroad and its philosophy will never change.

Products and Technologies

Why does Hardlock Nut stay tight?

The globally recognized Hardlock Nut works on the wedge principle

Removes thread space across nut height from both sides, providing strong return rotation prevention

●Reversing the order of the two nuts s (Convex & Concave)

The Hardlock Nut has a structure that prevents looseness through the traditional Japanese principle of the wedge.
To effectively utilize the wedge structure, two nuts are used: (1) a convex nut with an eccentrically formed boss, and (2) a perfectly circular concave nut. When these nuts are fastened together, the wedge principle mechanically creates a powerful locking effect transverse to the bolt shaft.

This powerful anti-loosening effect achieved with the Hardlock Nut wedge completely fuses the bolt and nut. Once locked with this powerful force, the Hardlock Nut is not susceptible to impulsive forces or shocks.

Fastener with non-rotational looseness

Cyclic Load

●Preventing rotational looseness caused by cyclic load from various direction

The Hard Lock Nut is a nut with different concavities and convexities for complete locking. Therefore, even when subjected to repeated external force perpendicular to the bolt axis, which is said to cause loosening of any screw fastener, the screw will not rotate back.

The initial tightening force can be maintained for a long period of time, making it a product with performance unparalleled any screws in the world.

Developed "Hardlock Bearing Nut" and "Hardlock Set Screw"

Hardlock Bearing Nut and Hardlock Set Screw

●For hollow stepped/ cylindrical shafts, from low to high speed applications

The HARDLOCK Bearing Nut (bearing lock nut) is retained using the wedge principal to reduce the gap between threads preventing loss of preload. Its high anti-loosening effect ensures stable and perfect fastening without being affected by vibration caused by high-speed rotation or impact caused by forward or reverse rotation, and enables significant cost reductions due to maintenance-free operation.

●For plastic molding, die Casting, to lock in place core pins and ejector pins

The Hardlock Set Screw is a revolutionary self-locking set screw (hex socket head set screw) which employs the wedge principle to deliver a superior self-locking effect like other Hardlock products without the need to change the conditions of the target application.

More information is available on the "Applications" page (see the bottom of the page for URL)

Case Study: Vertically Articulated Robot Axis (Joint) Stopper

Fastening points for vertical articulated robots

●Product: HARDLOCK Bearing Nuts

Vertically articulated robots have joints similar to human shoulders, elbows, and wrists, and can perform complex movements similar to those of human arms. Many vertically articulated robots have six movable axes, and in principle, six axes are enough to cover a full range of hand positions and postures.
The greater the number of axes, the more versatile the robot can be in a variety of postures.

(1) Applicable locations
・Locations where bearings are fastened with low axial force
・Locations where repetitive forward and reverse motion is performed.
(2) Improvement
・Fastening of bearings with low axial force was possible in areas where smooth movement is required.
・The maintenance cycle time has been significantly extended, which has resulted in longer operating hours and improved productivity.

Case Study: Fastening hook bolts for fixing sleepers on bridges

The railroad track of a bridge

●Product: Hard Lock Nut

The railroad track of a bridge is roadless (no ballast or slab), and when a train passes over it, the impact load and vibration of the train are concentrated on the fastening body. Hook bolts are used to fasten those sleepers to the bridge girders.

(1) Location of use
・Locations subjected to train impact loads and vibrations
・Sleepers cannot be tightened too strongly due to deflection to release the impact.
・Dangerous locations where the falling off of parts may lead to personal injury to people under the bridge.
(2) Improvements
・The burden of inspection work during nighttime inspection work has been greatly reduced.
・Safety has been improved by eliminating accidents caused by parts falling due to loosening.

Japanese website providing "safe and secure" fastening solutions for engineers

"Screw Fastening Technology Navi" (Please refer to the bottom of the page for URL)

Home page of "Screw Fastening Technology Navi

●Technical information site about fasteners in general and loosening

For engineers who have problems with screw fastening, please obtain specialized technical information in Japanese including the following from "Screw Fastening Technology Navi".

・Loosening of screws
・Design and tightening of screw fastener
・About Screws
・Problems with Screws
・Downloading documents

Corporate Profile

Corporate name
1-6-24, Kawamata, Higashi-Osaka City, 577-0063, Japan
Katsuhiko Wakabayashi
Founded / Established
1974 / 1977
Company URL

●Applications (

●Screw Fastening Technology Navi (in Japanese) (

Meet the President (

10,000,000 yen

Patent, ISO9001, JISQ9100