THE CHALLENGE IN BRIEF

Hiroyuki Yoshida, manager of the production department, looks through the combustion case.

The need: Nagoya Guidance and Propulsion Systems Works (NGPSW) wanted to cut down milling time for the manufacture of Trent1000 jet engine combustion cases in Waspaloy.

The solution: Rough operation: CoroMill 210 and a ceramic milling cutter with CC6060 inserts, removing large amounts of metal in a short time. Medium operation: CoroMill 300 with round inserts, allowing for low cutting forces, reduced notch wear and higher feed rates. Finishing operation: CoroMill 390 ensured secure machining with a stable tool life and no vibration with required surface quality.

The result: The machining time of the rough surface was cut down from 60–70 hours to 40 for one cycle, resulting in more than 300 hours of time saved per month. NGPSW was able to produce 10 combustion cases per month.

Located about an hour’s drive from Nagoya, a city in the heartland of industrial Japan, Mitsubishi Heavy Industries’ Nagoya Guidance and Propulsion Systems Works (NGPSW) represents the traditional values of corporate Japan. Company spirit is fostered by a lunchtime relay race with crowds of workers cheering on their teams. A family-like atmosphere is promoted with a huge cafeteria where everyone dines together – the highest paid employee next to the floor workers – and everyone brings his or her own tray to the kitchen.

Yukio Kamimura, the senior engineer of the production department, wears the same blue overalls as the rest of the factory crew, but on his right arm is a band acknowledging that he is a “distinguished employee.” In November 2009 he visited the Imperial Palace in Tokyo to be granted a Yellow Ribbon Medal of Honor from the Emperor of Japan. The award is the country’s highest recognition of professional contribution to the betterment of the nation.

For Kamimura, it was not one specific achievement but rather his 45 years of contribution to developing the aerospace industry in Japan that garnered him the prize.

Setup of cutting heads at Mitsubishi Heavy Industries’ Nagoya plant No. 5.

“When I first began machining HRSA materials 30 years ago, nobody really knew what to do,” he recalls. “We had to figure Kamimura’s contributions was the early technical development of machining C1 aircraft pistons, which were long and asymmetrical within 0.002 inch of concentricity. This type of advanced machining skills eventually led to the efficient production of turbine discs and combustion cases.

What made Kamimura’s award even more impressive was that it was the second year in a row that an engineer from NGPSW received the accolade.

“I think it’s a clear indication from the government that the aerospace industry is one that they are giving attention to and that our company has been instrumental in the development of this sector in Japan, which has a relatively short history [in the field],” says vice president Fumiaki Tominaga.

NGPSW develops, manufactures and repairs various parts of gas turbine aircraft engines in joint programs with industry giants such as Pratt & Whitney, Rolls-Royce and General Electric. In particular, the facility specializes in the production of heat-resistant engine parts. All the combustion chambers of large-size commercial Pratt & Whitney engines are manufactured here.

NGPSW is also responsible for the development and manufacture of the heat-resistant parts of the Geared Turbofan PW 1200G, a new type of engine for the upcoming Mitsubishi Regional Jet (MRJ).

In 2005, NGPSW embarked on an important risk-sharing partnership with Rolls-Royce to create combustion cases for the Trent 1000 series of turbo engines for the Boeing 787 aircraft. “Because of the necessity to withstand extreme heat, the combustion chamber is an extremely delicate part of the engine,” explains Hiroyuki Yoshida, manager of the production department. “The manufacture of this part requires a high level of technology expertise. We were entrusted with this project after a proven track record of more than 20 years making turbine blades and discs.”

Waspaloy was chosen as the material for the combustion cases because of its excellence in applications such as high-temperature engine parts. But it is also extremely difficult to machine.

A combustion case in Waspaloy is machined.

“In the aerospace industry, materials are going to continue to get more difficult to machine in order to improve the mechanical property at higher temperatures,” says Tominaga. “So overcoming this challenge was an important step in staying ahead with this trend.”

Yoshida was responsible for finding a solution. “Combustion cases have many parts, which makes the milling process both difficult and time-consuming,” he says. “In addition, our tools wore out quickly. We tried using the ceramic inserts we already had, but the wear was too great. We needed a better solution to fulfill our production goals.”

NGPSW talked to various toolmakers, but it was Sandvik Coromant that finally came up with the solution it needed. “Other companies recommended their products, but Sandvik Coromant worked with us closely to find the optimal performance level of their tools and to fulfill our objective of rough milling to 40 hours in a cycle,” elaborates Yasuhiro Sueyoshi, an engineer from the production department who worked directly on this project.

Yoshie Narita represents Sandvik Coromant distributor Sanwa Seiki, which oversaw the implementation of the solution from the beginning. He made almost daily trips to NGPSW and to the Sandvik Coromant Productivity Center to monitor the process.

“Good results do not come right away,” says Yoshida, recalling that it took almost six years from the time that tests were first conducted in 2001 to implementation on the production line in 2007. “But everyone associated with Sandvik Coromant responded quickly to our questions and provided all the support we needed.” Narita adds, “It was a long project, but when we reached our goal, it truly felt like a team victory.”

Mitsubishi Heavy Industries employees with the combustion case.

The success in machining the Trent 1000 combustion cases was pivotal in the relationship between NGPSW and Sandvik Coromant, but it was not the beginning. The companies had had a relationship for more than 20 years.

“When we find a technical solution together with a client, it forms a strong relationship between the companies,” says Noriyuki Matsumoto, Nagoya branch manager at  Sandvik Coromant Japan. “We had the opportunity to take members of NGPSW to Sweden and show them our research on ceramic cutting as well as our full range of products.”

NGPSW is now working on the Trent XWB, the new series of turbofan engines from Rolls-Royce, and Sandvik Coromant is again providing essential solutions. Sueyoshi says, “During our turning process, there was too much vibration. I consulted Sandvik Coromant, and they pointed out that vibrations came from having a weak tool holder. We are now conducting tests using the CoroTurn SL 70 with Coromant Capto in order to resolve the problem.

“For the rough milling of Trent 1000, we mostly used the high-feed CoroMill 210 cutter because we can quickly do facemilling and also make holes,” he continues. “But we have already pushed it to its maximum level. For the upcoming Trent XWB, we need to improve the conditions more. Sandvik Coromant tools are known to be stable, but we use them under difficult conditions. Therefore we need support.

“When I am faced with a machining problem, I can’t solve things by myself,” Sueyoshi says. “I can think up new methods, but I have no guarantee they will actually work. Sandvik Coromant provides realistic guidelines, and we can think through solutions together. Providing support, helping to figure out the best way to use the tools, is what sets Sandvik Coromant apart.”

From the experience of manufacturing the Trent 1000 combustion cases, Yoshida felt strongly that more research on the machining of HRSA must be done in a more expansive way. At the end of 2007, he created the Global Manufacturing Technology Team (GMATT). This virtual research group involves NGPSW, major universities and machine toolmakers and tooling suppliers in Japan. Sandvik Coromant is an essential partner in this group.

Since 2008 GMATT has conducted tests with ceramic milling and high-pressure coolant to improve the machining of the new series of Trent XWB jet engines.

NGPSW has been in the aerospace engine business since 1920. Production output stands at JPY 225.6 billion ($2.5 billion). It has almost 2,000 employees. The main plant covers 4,112,000 square feet.

“GMATT’s goal is to strengthen Japan’s aero-engine manufacturing industry with advanced applications in order to succeed in the world,” says Yoshida. “We will implement the new techniques we developed with Sandvik Coromant to the Trent XWB and PW 1200G engines.” In addition to GMATT, NGPSW has been collaborating on an application development project with Rolls-Royce at the Advanced Manufacturing Research Centre in Britain that also involves Sandvik Coromant. “Efforts like this are necessary,” says Tominaga, “because optimum solutions are found when all parts of the puzzle come together to make a bigger picture.”

Technical Insights

At Nagoya Guidance and propulsion Systems Works (NGPSW), the manufacture of jet engine combustion cases from Waspaloy is a complex procedure requiring a significant number of turnmill operations to remove large amounts of materials. “We had been working with NGPSW experimenting with ceramic tools for about seven years,” says Toshikazu Kawamukai, Sandvik Coromant Japan’s Aerospace SDC manager, “but it was not until the introduction of the CC6060 ceramic grades of round inserts that we experienced a major breakthrough.”

Because of the high speed required to mill Waspaloy, all other types of HRSA ceramic inserts lasted at most a minute – a tool life too short to fulfill MHI’s production requirements. But the new SiAlON ceramic CC6060 inserts lasted three minutes. “The grade has excellent notch wear resistance and allows machining at higher depths of cut,” says Kawamukai. The ability of the CC6060 to maintain performance at higher feed rates and in longer continuous cuts made it ideal to machine Waspaloy and other hard materials.”

NGPSW is keen to work with Sandvik Coromant to develop the usage of the CoroTurn HP for the machining of the Trent XWB series, Kawamukai says. “Because of the infusion of the high-pressure coolant jet, CoroTurn HP can help increase tool life, get better chip breaking and provide more secure and continuous machining,” he says. “We are currently working on how to best utilize this tool to produce the ideal solution.”

1. The cutting data of CoroMill 210 on casing at NGPSW: Vc=66–82 ft/min, ap=0.03 in, fz=0.02 in/tooth.

2. Data on CoroTurn SL70 used on rough ceramic turning: This has been developed mainly for jet engine components such as discs and casings to provide secure and productive machining.

3. Ceramic cutter information: Current cutting data: Vc=2,625 ft/min, ap=0.06 in, fz=0.003 in/tooth. These cutters were developed specially for casing components.

Learn more about Aerospace Solutions from Sandvik Coromant.

Originally published in Metalworking World 1.2010, a business magazine published by Sandvik Coromant.