Producing small lots of an extraordinarily diversified range
of bolts in a town known for producing knives.

Seki City, Gifu Prefecture, has been known for Seki blacksmithing since the Kamakura era and remains famous today as a place where knives are produced. Meira’s Seki plant and the No. 2 Seki plant are both located in a corner of an industrial park on the outskirts of Seki City. The company’s No. 3 Seki plant is also in Seki City, such that the city is home to a cluster of the company’s production lines.

Each plant is clearly divided into two zones. A number of very long automated manufacturing lines have been set up on the site where bolts for automobiles are manufactured. At one end of each line is a large site for the storage of materials. Wire rods supplied from this site are automatically processed on a line, and completed bolts are spit out from the opposite side of the line without stopping. Lines of trucks formed for just-in-time deliveries are parked outside the plant buildings, ready to ship freshly made bolts immediately upon loading to an automobile assembly plant.

At the same time, the site for the manufacturing of bolts for aeronautics and space applications is set in a separate part of the building where many artisans operate dedicated machine tools. A small materials storage site resembling part of a home hardware store carries not only steel items, but also aluminum alloys, titanium alloys, heat-resistant nickel alloys, and other special materials. Workers manufacture bolts by picking out the required materials on their own according to work instructions, setting them in the machines by hand, visually checking each individual unit, and checking units by tactile means.

About 100,000 bolts for aeronautics and space applications are produced monthly, a figure that is less by far than that for bolts produced for automobiles, 200,000,000 bolts per month. At the same time, many bolts for aeronautics and space applications are subject to a specialized design process to accommodate their use for a given part of a given model, such that there are over 6,000 different items produced. The harnessing of craftsmanship is the most rational means by which small lots of an extraordinarily diversified range of bolts can be produced.

The quality of screws is a function of both the materials used and the processing technologies applied. To date, Japan has produced high-grade bolts through collaborations between the steel and metal industry, which ships high-grade materials, and manufacturers like Meira of parts made possible by the harnessing of a high level of technology. However, the use of off-the-shelf general-purpose goods sourced from low-cost, mass-production overseas manufacturers even in the field of aeronautics has become common. Meira thus seeks to differentiate itself by building a framework for stably providing high-quality, highly unique products.

The No. 2 Seki plant, one of the sites where parts for aeronautics and space applications are produced by Meira (Seki City, Gifu Prefecture).

The head of a bolt is formed through hot forging.

Bolts for airplanes, which are made in greater quantities than bolts for space applications, are manufactured from coils using a serial forging machine.

Male screws are processed with a thread rolling machine. Precise thread-rolling technology is one of Meira’s competitive advantages.


In processing parts for making aircraft, a machining center (MC) (pictured on the left) or a multifunction machine (pictured on the right) is used that combines the functions of an MC and an NC lathe.

A tapping processing line for processing nuts (female screws).

Efforts are undertaken to absolutely ensure proper quality control. In this photograph, the diameter of a bolt is measured with a micrometer.

Fittings and other complex shaped parts are subject to size inspections using a three-dimensional measuring machine.

A swaging machine for processing rods as a structural material in aircraft, the Kounotori transfer vehicle, and other applications. The outer diameter of the pipe is narrowed through cold forging.

A rod processed with a swaging machine (front) and a pre-processed pipe (back).

A rod is subject to strength testing in a universal testing machine. Various tests, including pulling, compression, and bending, can be conducted in this testing machine.

A fatigue testing room. This photograph shows an array of different fatigue testing machines laid out in a row.

Nuts, bearings, and other items are mounted onto a rod processed with a swaging machine.


HQ Location Nagoya City
Established 1936
Main Facilities Seki Plant, No. 2 Seki Plant, No. 3 Seki Plant (Seki City, Gifu Prefecture)
Komaki Plant (Komaki City, Aichi Prefecture)
Main Products Bolts and screws for automobiles, bolts and rods in the field of aerospace, and osteosynthesis screw plates for orthopedics
Main Astronautics Equipment Produced Fairing separation bolts for the H-II and H-IIA/B rocketsUltra-heat resistant bolts for the LE-7A and LE-5B engines of the H-IIA/B rocketFittings, bolts, nuts, rods, and a rack-extraction jig for Kounotori, a space station transfer vehicleRods for anchoring the racks of the experimental setup in Kibo, Japan’s science module attached to the ISS (International Space Station)Bolts for releasing solar batteries mounted on satellites and structural bolts used with satellitesTitanium structural bolts for the Hayabusa, an asteroid space probe; and more.
Corporate site



The field of space is a dojo to be use forhoning our technologies.

Exective Director and Head of the Aviation Business Unit
Makoto Ohashi

What kind of manufacturer is Meira?

We were originally known as Nagoya Screw Works and were founded in 1936. As you might be aware, the Nagoya area is home to many aviation industry enterprises. Back then, however, Japan was unable to produce good quality screws for aircraft, such that there were many aircraft accidents caused by poor quality screws. In response to the wishes of Admiral Isoroku Yamamoto of the Imperial Navy, who expressed concern about the state of affairs, our company was established to produce aircraft screws by gathering together people from Nagaoka City, Niigata Prefecture, the same hometown as the Admiral. The latest machine tools for manufacturing screws were introduced from overseas and eventually reproduced. The screws used in the Zero fighter planes were also manufactured by our company.

After the war, the prohibition on the production of aircraft led to an increase in automotive-related sales in line with the trend towards increasing motorization. With the resumption of the production of aircraft, technologies for processing titanium alloys were acquired, which in turn caused industry categories to expand in terms of the production of screws, plates, and other implants for anchoring bones as part of healthcare treatments and the use of high-strength aircraft bolts in racecars.

In the field of space, our involvement can be traced to the time when standard bolts (bolts consistent with specifications prescribed by U.S. forces) came to be used in the field of space. Our first bolts for space applications were bolts used for the N-I rocket (launched in 1975). Bolts used with aircraft were redirected for this purpose. Thus, we did not necessarily intend to participate in the development of products for space. Instead, it felt as if we were led to this point in the ordinary course of events.

What are the significant points of difference between bolts for space applications and bolts for other uses?

Our products can be broadly classified as products for automobiles, products for aerospace applications, and products for medical purposes. Bolts for automobiles are mass-produced by equipment designed with an emphasis on automation and delivered on a just-in-time basis. What is important is kaizen (improvements), so that everything from the design to the manufacturing stage is constantly reviewed to determine whether or not high-grade bolts can be made at lower cost. In contrast, bolts for aircraft are designed with care and vigilance in an effort to produce good products. Once the design and manufacturing processes are properly defined, production proceeds continuously. Unlike with bolts for automobiles, safety considerations impose, in principle, a prohibition against alterations to the manufacturing process. Bolts for space applications are produced in smaller batches than bolts for aircraft. As uses are specialized, focus is then on design capabilities. Reliability is of paramount concern. In this connection, the management of the manufacturing history, in other words, traceability, is subject to exceedingly strict checks. For instance, if there is a product whose dimensions are measured with a micrometer, you will need to record even the exact micrometer with which measurements were taken.

Which products made for space applications have left a particularly big impression on you?

I would have to say the fairing bolts on the H-II rocket. These are titanium-alloy bolts for joining the left and right sides of payload fairings on the end of a rocket. Notches are cut partway up each bolt. Tubes containing explosives are set where the fairings are joined and tightened with these bolts. The design is such that, when these explosives are triggered to open up the fairings, the tubes expand, the force of this expansion causes the notched part of each bolt to break away and therefore the fairings open up.
When fairings are fixed in place, there must be no breakage at the time of the launch. At the same time, if the explosives inside a tube were to go off, breakage must occur cleanly. The task of guaranteeing reliability was difficult and caused us to experience significant hardships in the development of our bolt. Thanks to this project, this bolt has been used not just with the H-II rocket but also subsequently with the H-IIA and H-IIB rockets. Our ultra-heat resistant bolts are also being used for the LE-7A and LE-5B engines of the H-IIA/B rocket.
Bolts to affix debris bumper panels to Kibo, a Japanese module attached to the International Space Station (ISS), are also produced by our company. Protective material referred to as bumpers to lessen the damage caused by space debris is attached to the surface of Kibo on a raised basis. Since an astronaut wearing a suit may be called upon to swap a bumper during a spacewalk, we developed bolts that could be safely replaced with special tools and the gloves that form a part of the space suit. The development we undertook while maintaining close communications with JAXA and NASA was a tremendous learning experience.

In addition to screws, we also manufacture the rods used to support structural materials. Through the design, manufacture, and evaluation testing of bolts for aviation purposes, we have accumulated expertise in advanced structural parts. By harnessing aluminum processing technologies for rivets and other such items and technologies related to nuts and other female screws, we have also entered the market for rods used in aeronautics and space applications for which both lightness and strength are required. We have also delivered rods to anchor the racks of the experimental setup on Kibo. These aluminum-processing technologies have evolved into machine-processing parts based on the use of a machining center and now account for half of our sales in the field of aerospace. Fittings used with Kounotori, a space station transfer vehicle, are an example of what I am talking about here.

Could you break down your sales for our readers?

Products for automobiles, for which 200 million bolts are produced monthly, account for an overwhelming proportion of our sales. Products for automobiles account for over 80 percent of our sales while products for aeronautics accounts for a bit over 10 percent and products for medical applications account for approximately 6 percent of sales. Although products for space applications account for a percentage of sales that varies from year to year, I would say that they represent about 2 to 4 percent of the total sales in the field of aerospace.

How is the field of space being positioned by your company?

We believe that the field of space is a dojo for honing our technologies. This is because the romantic appeal of space inspires us to take on challenges and because difficult problems help our engineers become better at what they do. In this connection, the technologies and expertise we obtain can be deployed in consumer (civilian) fields and induce us to take on additional challenges. For this reason alone, we would like to request new challenges and large projects from JAXA. More than anything else, investments along these lines allow us to obtain engineers with exceptional levels of skill. It should be noted that manufacturers of products for space applications (like manufacturers of products relating to aeronautics) handle low volumes, which in turn presents a huge problem. Namely, how does one pass on, maintain, and develop techniques and skills and maintain manufacturing capabilities? In order to maintain our ability to manufacture bolts and rods for space applications, I believe that a market with a certain degree of critical mass is required. In addition, in order to deal with efforts by emerging economies to catch up to Japan, our country needs to maintain our technological fundamentals, strengths, and networks.