Prise winners list

Overturning common knowledge, 'Screws, although fastened, eventually work loose,' a revolutionary nut that never becomes loose, has won worldwide acclaim.

Higashi-Osaka-City, Osaka Prefecture
Hard Lock Industry Co., Ltd.
Other award winners
Recommended by
Venture Labo Co., Ltd.

Wakabayashi, Katsuhiko  (76)
Representative Director and President

It is safety that we develop In order to create a perfect product, there is no choice but to do it by myself.

Utilizing the wedge principle found in traditional Japanese architecture, Hard Lock Industry Co., Ltd. has resolved the problem of loosening the grooves in a bolt and a nut. Their innovative product, Hard Lock Nut, prevents a screw from becoming loose by using two nuts to fasten the screw: an upper, concave nut on a lower, convex nut. Due to this feature, it has been applied to areas where maintenance is difficult or which are exposed to harsh vibrations or strong impact, such as iron towers, long bridges, railcars, and nuclear power plants, demonstrating its outstanding function for over 30 years. Hard Lock Industry also has proven the remarkable safety of their products, using testing machinery which is one of the best in the world. Their enthusiasm for safety and quality has won trust also from overseas manufacturers. With the policy, "Develop safety," Hard Lock Industry has released state-of-the-art product lines such as "HLB (Hard Lock Bearing Nut)" and "Space Lock Nut."


Creating a company twice in search of a nut that never becomes loose, he finally realized his dream nut.

The story is traced back 60 years. Mr. Wakabayashi, who was working for a valve maker and responsible for design, encountered, at an international exhibition, a nut which had a mechanism preventing a screw from becoming loose.

Mr. Wakabayashi says, "I brought the nut back home and looked at it for an hour before going to bed. Then, I had an inspiration - a method to make it that wouldn't cost much."

Mr. Wakabayashi developed U Nut, a first non-loosening nut, utilizing a spring. Then he established a company to make it business, two years after he got the inspiration.
 "At first, I was unable to make wholesalers understand my nut using a plate spring. They angrily told me not to bring them such a strange thing," he says with a smile, "I took the nuts directly to factories of nut makers and gave them the nuts to try for free."

Through his sales efforts with sweat and tears, and helped by the rapid economic growth at the time, the sales of U Nut grew to one of the largest market shares in the industry. Mr. Wakabayashi, however, already knew the weakness of U Nut. He explains, "The nut can become loose when it is applied to a machine receiving strong impact, like an excavator, for example."

For the purpose of creating an ideal nut, he gave up all the manufacturing rights of U Nut and founded Hard Lock Industry in 1974.

He says, "I got the idea for the Hard Lock Nut from the torii, or shrine gate, at Sumiyoshi Shrine, an example of traditional Japanese architecture. The torii has wedges which prevent loosening. With this hint, I started development from scratch. At first, my idea hardly became tangible. 

After trial and error, he came up with that method to lock a screw by sliding a wedge using two nuts: an upper, concave nut on a lower, convex nut. The structure requiring two nuts means more workload, or a serious disadvantage, but Mr. Wakabayashi stuck to this method, because he wanted to achieve "safety," which is irreplaceable. 

He recalled, "Anyway, I strongly felt that there was no choice but to do it by myself. I also felt that I mustn't develop another product at the same time, thinking I would hurt both. It was like rearing a child. A child takes time to become able to walk and needs much care. It took five or six years for the Hard Lock Nut to become a business."

35 years of no accidents The high quality of safety has become a world standard

"I am happy when I can be useful to others. You should not be attached to making money. Still, I want to earn a fair profit," Mr. Wakabayashi says with a smile, "But a self-centered way will never work." 

His philosophy has been realized in such a way that the Hard Lock Nut has caused no accidents for 35 years since its birth, neither have any other products of the company. They are used for industrial machines, aircraft, ships, railway equipment, among which are bullet trains, big bridges like the Seto-Ohashi and Akashi Kaikyo Bridges, and "Tokyo Sky Tree," the new Tokyo Tower to be completed in 2011. Nuclear power stations, wind generation facilities, and interestingly, jet coasters and the edges of runners for bobsleds are also some of their applications. Even though products of his company cannot be seen, they support vital parts of our life.

About overseas markets, Mr. Wakabayashi says, "Our Hard Lock Nut is used for rail fastening devices for Taiwan High Speed Rail." The company also has been certified by railway companies in the UK and Australia, thus expanding its market to over 20 countries and regions over the world.

The products they are producing are stout yet resilient, i.e. reliable support players. Their products are unmatched, however, there is something else about this company that is special. 

There is a unique space on the second floor of the third factory. That is where a large collection of model railways, Wakabayashi is deeply attached to, is placed close together. The diorama is superb, but the most striking item in the collection is a steam locomotive of one thirteenth size. It can actually carry a man to go round the 80-meter railway. He says with a smile, "It is very popular among our partners visiting our factory. They can play with it. It does such a good job that you could call it a sales person."

The "meeting room" is full of playful thinking. This must be one of the places where he is motivated to research untiringly for safety and come up with ideas. When he was a college student, he invented an ink bottle which didn't put extra ink into the tip of a pen. Soon after he established a company, he made a holder for square paper like a toilet role, and also a Japanese omelet pan with an added little angle which enables you to make a Japanese omelet easily. For the flexibility of his ideas, he has got the nickname of "Edison of Naniwa". Not limited to the Hard Lock Nut, he is still absorbed in hammering his ideas into shape so as to provide more perfect safety.

Hard Lock Industry Co., Ltd.

Apr. 1974
10 million yen
48 (as of Dec. 2009)
Brief information:
Hard Lock Industry shows meticulous care in quality management by conducting product tests in their own production facilities, with testing machinery they have made in accordance with industry standards.

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The nuts have to come in a variety of sizes according to where they are fixed. In most cases, they are used in places where maintenance and replacement are difficult. They also need to withstand heavy weight and rust. In order to respond to various requirements, the nuts are made from different materials.


The company's nuts are certified by railway companies for use in railway devices not only in Japan, but also in over 10 countries. About 4 million sets of Hard Lock Nuts were delivered to Taiwan High Speed Rail for use in various fastening devices.


Top-level equipment for 100 % inspection test. It measures the height of nuts and the inner diameter of screws to the extremely high accuracy of one thousandth of a millimeter. The trust they have won derives from this rigid inspection system.