FOCUS on PERFORMANCE
FOCUS on PERFORMANCE
IHI handles the production, assembly and maintenance of aircraft engines at four plants: the Kure Aero-Engine & Turbo Machinery Works (Kure City in Hiroshima), the Mizuho Aero-Engine Works (Mizuho-cho, Tokyo), the Soma No.1 & No.2 Aero-Engine Works (Soma City in Fukushima). The IHI Soma Works, the largest IHI plant, is located in Onodai, 10 km inland from the Pacific Coast in Fukushima Prefecture.
The Soma No.1 Works was established as the fourth manufacturing base of the Aero-Engine, Space & Defense Business Area in 1998 with the partial transfer of Tanashi Aero-Engine Plant functions to handle the manufacture of aerospace engine parts. In 2006, the remainder of the Tanashi Plant functions were transferred to the Soma No.2 Works. The Works has electric wiring and compressed air piping along the beams of the building to supply each piece of equipment. This allows the free layout of equipment to facilitate flexibility in responding to changes in demand. The Works are clean and free from the odor of the machining oil, which allows employees to work in comfort.
With demand in the aerospace industry expected to rise, the need for eco-friendly aerospace engines will increase. There is an interest about manufacturing at the Soma No.2 Aero-Engine Works, where low-pressure turbine parts are manufactured. In this feature, Ryoji Takahashi, General Manager, Masayoshi Ando, Engineer, and Hatsuo Okada, Manager were interviewed at the Production Engineering Department, Soma No.2 Aero-Engine Works.
How do the Works’ strengths contribute to the high market share of IHI?
Takahashi: “IHI has long experience and extensive know-how in the manufacture and assembly of aerospace engine parts. Shaft and low-pressure turbine parts are our specialty, and they are highly regarded by our customers. Our company has grown through contracts for the Ministry of Defense; however, the sales ratio of commercial aerospace engines has increased. In addition, IHI is one of the few companies that boasts the wide range of skills and technology required to handle the entire engine manufacturing process.”
Could you tell us about the depth of aerospace engine part manufacturing?
Takahashi: “Many of the parts that go into aerospace engines are made of light, but extremely strong materials, which are difficult to cut; and the required machining accuracy of most of these parts must be within 0.01mm. Our thoroughly managed manufacturing processes ensure the production of high-quality parts. Engine development requires tool machining tests and performance evaluations normally conducted over an extended period of time to determine the final manufacturing processes. Once registered, tools employed in the manufacturing processes cannot be easily changed. Of course, if productivity can be significantly improved, it is well worth the effort to consider changes not only in the tools, but also in the manufacturing processes. Any changes, however, must adhere to strictly determined procedures. Because we need to follow the procedures for changes in tools and processes, undergo strict screening, and obtain approval, we need to plan with great care to avoid costly delays. This principle is fundamental to our mission to design manufacturing processes that achieve high accuracy machining and high productivity before mass production.”
What is the current state of aerospace engine part manufacturing?
Okada: “In an effort to extend flight range, development of next-generation aircraft with high-performance and high fuel efficiency has been actively pursued. The engines installed in such aircraft require new materials that feature higher temperature durability and lighter weight.”
Takahashi: “Therefore, composite materials have often been employed in engine manufacturing over the past 10 years. To reduce CO2 emissions and lower the cost of transportation, improved fuel efficiency is essential. This is why the use of light, strong CFRP and CMC has been increasing. Meanwhile, convention metals are still required and metal alloy development has been pursued to increase strength. Increasing the strength of the material makes it thinner and lighter, which increases fuel efficiency. However, machining has become very difficult with the development of composite materials and highly strong alloys. Expanding aircraft demand means heavier air traffic, and that means increasingly severe standards regulating environmental load.”
What is the relationship between material improvement and machining technology development?
Takahashi: “Weight reduction is very effective. For example, reducing the weight of rotating parts leads to a reduction in the weight of bearing and stationary components. Reducing the overall weight of the engine achieves a significant improvement in fuel efficiency, which has a dramatic effect on operating costs. At the same time, this reduces environmental load. However, as material strength increases, machining becomes more difficult. Expanding the industry requires the further development of machining technology. It is very important to have both high-quality cutting tools and machining technology to reduce material weight.”
Ando: “Recent components employed in aerospace manufacturing are made of extremely expensive and difficult-to-cut materials. Therefore, it is important to design processing methods that prevent damage to products even when tools break during machining. In addition to manufacturing high-quality products while reducing machining costs, which is our primary mission, we also strive as much as possible to prevent damage to products.”
Okada: “As materials continue to improve, current machining methods may not be capable of processing them. Even if current machining is retained, materials may be processed using other methods, methods such as laser and electric discharge machining. Cutting tools may be completely different from what they are now.”
Okada: “Let me give you a recent example. We needed to significantly improve disk productivity in response to the increased production of aerospace engines due to expanding demand. We traditionally applied broaching to process dovetails, the joint used to install the blade on the disc; however, the broaching machine is extremely expensive and tool manufacture requires a relatively long period of time. In addition, broaching is a machining method with low cutting levels, which made it difficult to significantly improve productivity. Therefore, we sought a completely new machining method. First, we applied milling to the rough machining of the dovetail. It has been two years since we began development, and we are almost ready to institute the method. The merit of milling is stable tool availability, and the forms and materials are easily improved. Productivity is also significantly higher than broaching. However, there are also some drawbacks. Tools per machining volume in broaching are less expensive than those used in milling. For milling, we needed to reduce the total cost of tools, a goal we realized by minimizing the number of tools employed utilizing appropriate tool path and maximizing tool life. Although we faced many challenges during the shift from broaching to milling because of our lack of experience, young staff worked persistently to overcome each challenge. At the beginning of the shift, when tools were frequently damaged during machining tests, I sometimes felt that we would have to give up. However, support from Mitsubishi Materials staff helped us to continue moving forward in designing machining methods, creating prototypes and evaluating the product. The efforts and enthusiasm of the engineers at both companies led to this success.”
The development of excellent engines means achieving the highest precision and lightest weight possible. Improvement of precision leads to the reduction of energy loss, and weight reduction increases output per weight. This also leads to the improvement of environmental performance through the reduction of fuel consumption, noise and gas emission. The key to such improvement is progress in the development of materials such as high heat-resistance and lighter weight, plus machining technology must keep pace with that progress. The mission of the Soma No.2 Aero-Engine Works is to continue developing new products based on such high machining technology.
At the end of the interview, Ryoji Takahashi, General Manager of the Production Engineering Department, said, “There is a particular business model for the development of commercial aerospace engines, whose IHI sales ratio has been gradually increasing. It is a development program, the international partnership. Commercial aerospace engine development requires an extremely high investment of time and money. This program, therefore, offers international joint development through a partnership among the best players in a wide range of areas. To disperse risk, each partner’s costs of development are proportional to its ratio of investment. Furthermore, partners establish long-term strategic relationships for each part they take charge of, handling such responsibilities as manufacturing, technical development, product support, after market services (spares, engine maintenance services). IHI’s strength is its know-how in integrated manufacturing for most aerospace engine parts, and its ability to discuss individual strengths, such as shafts, compressor parts and fan parts, etc. with partners to expand the services it can offer to the market. Expanding the range of parts in its specialty business, IHI competes confidently with global competitors. In order to achieve its goal of becoming the world’s top plant, IHI strives continuously to achieve and maintain global-level manufacturing, quality management and machining technology to ensure the highest level of manufacturing capability. We are very excited about the possibility of installing engines that IHI has developed into commercial aircraft, engines that feature parts made in Japan. This is a common dream among those of us engaged in the development and manufacture of aircraft in Japan.” From Soma to the world, we continue working hard to improve our technology at the IHI Soma No.2 Aero-Engine Works.