MMC Magazine

(Marumori Town, Igu County, Miyagi Prefecture)

A large vacuum chamber manufacturer with a high technical capability is achieving remarkable growth with aggressive capital investment reaching 10 billion yen over the past 30 years.

Manufacturing large vacuum chambers by implementing large equipment

In the manufacture of semiconductor wafers, liquid and organic EL panels, it is essential to have a chamber (container) to create the vacuum environment required to prevent contamination by air, gas, steam, fine particles or other foreign substances. Melco Japan in Miyagi Prefecture has the largest market share of large-size vacuum chambers in Japan.

Masuyuki Kurita, Chairman of Melco Japan, founded Kurita Special Steel Corporation in Hitachi City, Ibaraki Prefecture in 1960. The company sold press mould materials and special steels. “My elder brother engaged in the wholesale of metallic materials in Tokyo, so I decided to start a business in a related industry. I could purchase materials from my brother’s partner companies, which was beneficial in a start-up environment,” he said. In response to the relocation of supplier’s plant to the countryside soon after foundation, Kurita Special Steel Corporation also expanded its business to the countryside. The company established bases in the Northern Kanto and Tohoku Regions in locations such as Hitachinaka City in Ibaraki Prefecture, Iwaki City in Fukushima Prefecture, Sendai City, Kitagami City, Yamagata City to expand its sales networks. The company only had a single machine when it opened, but it gradually increased its range of equipment.

However, entering the 1980s, major special steel trading companies expanded their business to the countryside and this meant fierce competition started. Mr. Kurita knew he had to have something distinctive beyond special steels to survive in the industry, so he decided to handle stainless steels that were not commonly used at that time, he also felt that they had the potential for a broad range of applications in the future in such fields as industrial equipment and construction. His thinking was correct. Orders for stainless steels began increasing each year, prompting the company to establish storage space and logistic bases. The company built the Materials Stock and Machining Center in Marumori Town, Igu County, Miyagi Prefecture. The reason for choosing the town of Marumori was that the company could purchase a large tract of land to store a large inventory. The property was located almost at the centre of the business bases, which was very convenient for supplying materials.

A few years after the Marumori Plant started operation, a procurement manager of the partner company asked Melco Japan to accept outsourced work using five or six machines that the partner company would provide at a generous discount. Mr. Kurita jumped at the chance and secured a loan to purchase the machines for the Marumori Plant. Melco Japan handled simple work machining stainless steels for a while and their extremely accurate techniques and beautiful finishing became highly regarded and this led to an increase in cooperation with partner companies. After accepting the work of machining vacuum chambers, Melco Japan introduced welding equipment, hired new engineers and established the base of the current Marumori Plant.

The current Marumori Plant has an integrated manufacturing system, from stainless steel cutting, plate working, welding, machining and electropolishing through to sheet metal working. The plants’ main feature is that it’s equipped with many large machines. Mr. Kurita said, “We aren’t manufacturing small products that other companies can also produce, but large vacuum chambers in the 10- to 20-ton range, and this has made Melco Japan a well-known name both at home and abroad. Our ability to supply products at all times, an ability supported by an approx. 8000-ton stainless-steel inventory, together with the technical capability of excellent craftsmen have helped us establish a trusting relationship with customers and grow our business.”

In spite of such strengths, the Marumori Plant has focused on the manufacture of large vacuum chambers rather than small products and precision parts. They also encountered a huge gap between the peak and low demand seasons. In 2014, the company applied to the Subsidy Programme for New Business Establishment in the Areas Recovering from Tsunami and Nuclear Disaster towards Employment Creation (2nd) provided by the Ministry of Economy, Trade and Industry. In the following year, the company purchased property and built Seaside Plant I in Yamamoto Town, Watari County, Miyagi Prefecture for 2 billion yen. Then, applying to the same subsidy programme (8th) in March 2021, they built the 2nd plant for 2 billion yen. About half of the costs to build both plants were paid with the subsidies on condition that the company hired people from the local communities.

“Since the establishment of the Marumori Plant, we have invested about 10 billion yen over 30 years. The reason we could invest such a large amount of money is due to customer trust. We did not have manuals to manufacture large vacuum chambers. Our engineers gave exerted efforts to improve the technological capability by trial and error, and thereby accumulated our unique know-how.”

We asked Mr. Kurita what he looks for in a tool manufacturer. He quickly answered, “A desirable tool manufacturer for me is the one capable of promptly supplying high quality at a low price.” He continued with smile, “I’m hoping that Mitsubishi Materials will develop a wider range of tools suitable for machining a diverse range of stainless steel materials. Let’s do it together.”

Due to COVID-19, market demands have dropped slightly; however, Mr. Kurita predicts that a broad range of manufacturers will move forward with large-scale capital investment from now. “Along with increases in the size of car navigation screens and expanding energy-saving systems, demand for organic EL will certainly expand, and orders for vacuum chambers will likely grow. In addition, we think there is a good chance of receiving orders for vertical vacuum chambers developed by semiconductor production equipment manufacturers.”

As the above demonstrates, Melco Japan is now enjoying favorable winds and Mr. Kurita is responding to the increase in demand for their products through aggressive capital investment. “Looking beyond the present, I would like to consider the company’s environment and growth in five or ten years to continue capital investment to ensure the stability of the company for the next generation,” he said enthusiastically. Looking young in spite of his 88 years, he is very energetic and always looking toward the future.

Establishment of a flexible manufacturing system (FMS) that realises automation and unmanned operations

The Seaside Plant in Yamamoto town manufactures vacuum chambers, semiconductor production equipment parts, aircraft parts and components for nuclear power plant decommissioning equipment. Plant II, established in March 2021, has two lines, the MAZAK Line and the OKUMA Line. The MAZAK line has a flexible manufacturing system (FMS) for 24-hour automated and unmanned operation that connects four units of five-axis machining centres and unmanned pallets. When components are set on the pallets by an operator in the FMS, the machine automatically selects those to be worked on and conveys them to a machine tool for setting. After the materials are machined automatically according to the programme, they are returned to the pallet and the next machining cycle starts with the selection of the necessary materials.

“At plants like ours that are operated by a small number of people, automation is essential. Having employees operate machines during the daytime and implementing unmanned operation at night solves manpower shortages, reduces lead times and decreases human error,” said Seaside Plant Manager Yoshiya Ishizuka. Hiroki Izumi of the FMS Department looked back on the difficulties they faced when designing the FMS line, and said, “Although we knew much less about conveyer systems than we did about machine tools, conveyer systems are extremely important for automation. Therefore, we learned the basics. The most difficult part was the use of multiple materials because it required more complex movements than transporting a single component. Also, because machines automatically determine the order of priority, we need an operator or a programme to adjust the order.”

In addition to the FMS, the plant has implemented a wide range of innovations to improve efficiency. For the MAZAK machining centre, an IC tag is placed on the pull stud side of the main axis to manage tools. Originally, we wrote the type of tool, machining method and name of the responsible person on a sheet of paper when removing tools from tool magazines. Shifting to IC tag management reduced the time needed to document the information, and it also vastly reduced mistakes. The location of tools is now tracked by PC and the optimum tool / holder combination and other information can be shared among staff engaged in the machining process,” said Mr. Izumi, emphasizing the merits of increasing work efficiency and reducing mistakes.

The Okuma Line consists of one large lathe and three machining centres. The Okuma portal machining centre can change spindles, which makes it possible to machine both stainless steel and aluminium. Machining aluminium requires high revolutions compared to stainless steels, so we set the max RPM at 10000 and increased the durability of the machine body.

Digitalizing the experience of veteran engineers to pass on to the next generation

The strength of Melco Japan does not reside merely in the power of its equipment, but also in the technological capabilities that have been so highly regarded by customers. Vacuum chambers need to have minimum gas leakage and permeation as well as occluded gas discharge as absolute requirements. Along with the improvement of high-precision liquid panels and semiconductor chips, quality checks by manufacturers have become increasingly stringent, therefore the strictest attention is paid to ensuring machining accuracy, airtight welding and that products are free of scratches. “Melco Japan has many experienced engineers capable of satisfying the tight range of dimensional tolerances in the machining required by customers. In addition, in terms of stainless-steel welding (TIG welding), our products are highly regarded because of their excellent airtightness along with the perfect finishing. For the final process of manufacturing, we have installed large precision cleaning tanks to ensure complete removal of all cutting oil on screw threads and in holes,” said Plant Manager Ishizuka proudly.

Susumu Mito from the Production and Technology Department gave us an example of the high level of their machining accuracy. “We were asked to machine products to f6-class hole dimensional tolerance (-0.062 – 0.098) for Ø400. The customer was having difficulty finding a company that could handle the job, but Melco Japan decided to accept the order. Through basic discussion with engineers using drawings, we were able to manufacture the product within the designated dimensional tolerance. Since then, we have continued to manufacture the product for others and we are proud to say that we have never had a single customer complaint,” said Mr. Mito. However, even with such high accuracy, their products rarely have scratches. “We never reuse a machining method that has caused damage to products. For example, because spot milling caused damage when conducted after drilling, we changed the order and drilled holes after spot milling. As a result, we could prevent surface blemishes.”

“Our task now is to pass down the technological capability of our experienced engineers to the next generation,” said Mr. Ishizuka, Mr. Izumi, and Mr. Mito. “We are now digitalizing the experience of veteran engineers to avoid becoming dependent on subjective judgment. For example, when tightening with a clamp, we stay away from abstractions in our explanations by using specific values such as “45 degrees from this direction” to ensure every engineer can achieve the same accuracy,” said Mr. Izumi as an example of their approach to cultivating young engineers.

Improving quality by prioritizing communication with cutting tool manufacturers

Melco Japan engineers prioritize communication with tool manufacturers. “For products that we are machining for the first time, we often consult with cutting tool manufacturers about the selection of tools and machining procedures,” said Plant Manager Ishizuka. Mr. Izumi followed up by saying, “About the spot milling I mentioned before, I also received advice from Mr. Hiratsuka, Mitsubishi Materials Sales Division. Mr. Hiratsuka always replies promptly and is also quick to deliver tool samples to us, although cutting tool manufacturers are often reluctant to do so if they aren’t sure yet that they’ll be receiving an order. I feel comfortable and free to ask him about anything.”

When asked what kind of tools people at production sites are looking for, Mr. Ishizuka, Mr. Izumi, and Mir. Mito answered without hesitation, “They have to be cost-effective and have a long tool life.” “Tools provided by Mitsubishi Materials are slightly more expensive; but their quality is excellent, which improves productivity and durability, resulting in longer tool life and finally a better cost performance ratio. We would like to further increase our purchases,” said Mr. Izumi. In response, Mr. Hiratsuka from the Sales Division said, “We recently delivered an AXD4000 cutter for machining aluminium alloys and difficult-to-cut materials. We first provided samples for the customer to compare on actual components, and this ultimately resulted in receiving the order.” Plant Manager Ishizuka gave his impression about the delivered products, “The AXD4000 is expected to improve the machining processing rate and increase tool life by adopting helical machining.” Mr. Shibata, in charge of technical support at Mitsubishi Materials said, “Reinforcing the partnership, we listen to Melco Japan’s suggestions about products, which leads to new product development and improvement.”

Mr. Ishizuka, Mr. Izumi, and Mr. Mito then finished up by telling us about what their focus will be in future manufacturing. “At present, we are advancing the construction of the fourth machining centre connected to the FMS, aiming to start operation next spring. We would like to continue machining during both day and night to improve productivity.” (Mr. Ishizuka) “I was taught by my senior co-workers to assure customers that machining is absolutely possible with drawings alone. With the belief that everything with a shape can be processed, we strive to continue improving our techniques.” (Mr. Mito) “Our current goal is to establish a 24-hour operation structure. Our chairman often reminds us to include the spirit of the Mitsubishi Materials Corporation in the design and manufacture of every product we produce to ensure that we always deliver the highest quality to our customers.” (Mr. Izumi)

There are only a few companies, not just in Japan, but in the world, that handle the large amount of stainless-steel machining that Melco Japan does. Reinforcing this strength, Melco Japan will continue expanding its business from manufacturing vacuum chambers to parts for semiconductor production equipment and for aircraft parts.