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"Gaining New Insight Into Aluminum Body Production"

Remarks by Kazuhiko Tsunoda, Chief Engineer of the Honda Insight

Good morning ladies and gentlemen. I am here today to talk about the second greatest challenge of my life – the development of the aluminum body structure of the Honda Insight gas-electric hybrid vehicle.

As the most fuel efficient gasoline car in history, the Insight is an important environmental milestone. This morning I will explain some of the key technologies used to create the Insight. But you may not be aware that many of these technologies are linked to Honda's racing activities. Honda has been involved in motorcycle racing since the 1950s. And we began auto racing in the ‘60s. We have won Formula 1 championships in the ‘80s and CART titles in the U.S. in the ‘90s. But racing achieves more than just championships. It trains our young engineers. It motivates everyone in the company, as well as our customers and fans. And it helps create new technologies that we introduce to the marketplace.

Honda's experience in racing has provided us a lot of expertise in aluminum frame construction. The race car that earned Honda's first F-1 win in the ‘60s had an aluminum monocoque frame. And, as a young engineer in 1982, I led the design of an aluminum space frame for the NS500R motorcycle race machine, which won a World Grand Prix championship. This bike utilized extruded aluminum parts. As I will explain in a moment, the aluminum body of Insight was developed based on technologies gained from these challenges.

But, from a macro perspective, the challenge of building a gas-electric vehicle is two-fold. First, to achieve advancements including lightweight technologies represented by the all-aluminum body, a unique aerodynamic design and a new powerplant. Second, to make this product both desirable and affordable for the customer.

Our work toward this challenge utilized Honda's great experience in the development of environmental vehicles. This environmental commitment is borne out of Honda's core philosophy – a belief that we must think about the people who use our products and the world in which they live. And we view our products as the best expression of this commitment. This has given Honda a real passion for the environmental challenge.

Honda's strategy has been to lead the process of developing new environmental technology -- not simply to wait for new laws. Waiting for regulations would put you behind in the technology race. And it would require patching new technologies onto existing products. This would mean quality, performance and cost penalties that impact both the customer and the company.

As you saw in the video, Honda has always followed a challenging spirit in meeting the environmental challenge. In 1973, a Honda Civic became the first automobile to meet the Clean Air Act based only on engine performance.

Through Honda's commitment to the environment we have learned a lot about what it takes to win customer acceptance of environmental technologies. For instance, in 1992, Honda introduced the Civic VX Hatchback. It offered new fuel efficient technology available at the time. And it averaged an industry-leading 56 miles per gallon on the highway. Still, the VX did not sell as well as we hoped. But, this project was not a failure. We learned that for an environmental technology to succeed – and to have a positive impact on society – it must be accepted by the customer.

More recently, our commitment to develop low emission vehicles has focused on developing advanced internal combustion technology. And we have introduced these advancements on mass market vehicles ahead of mandates. This year, more than 80 percent of the Honda and Acura vehicles sold in America are LEV or better. The key is that our customers don't have to sacrifice performance.

Today, because of the importance of market forces, Honda environmental technologies are designed not only to make the world a better place. We must make cleaner cars that people actually want to buy. This means more performance, safety and comfort, in vehicles that also use less fuel, produce fewer emissions – and, yet, at reasonable prices.

At Honda, because this customer-driven approach is a result of our core philosophy, it means the development of environmental technologies is integrated into our business plans, and into the fundamental concept of each new product.

This was our strategy with the Honda Insight gas-electric hybrid vehicle. I have heard it said that Insight is just a rolling laboratory. In fact, Insight does feature new technologies and we used new production technologies to build it. But I can tell you that we did not view Insight as a test car or a prototype. We view it as a real world product for the global market. That is why we have introduced it in Japan, the U.S. and Europe. And our customers seem to agree -- the Honda Insight is proving to be very popular with customers in the U.S.

The key is the concept – our goal was not only to make Insight the world's most fuel efficient mass production car. We also wanted it to be low emission, to meet advanced safety standards, and to be fun to drive.

When you consider the challenge of developing the world's most fuel efficient car, the attention naturally goes to the powerplant. With the Honda Insight, this is easy to understand -- because it is the first gas-electric hybrid car sold in the U.S. And our IMA technology is very innovative, but simple. We adopted this approach because we did not want our customers to be intimidated by the technology. Again, the key is that our customers are not asked to sacrifice their driving experience.

But the high fuel efficiency targets are not due only to the IMA powerplant. The aerodynamic design and lightweight technology were critical to achieving record fuel economy including use of aluminum for the skin and the frame. And key to the greater use of aluminum was the ability to use these materials at lower cost.

Obviously, we chose aluminum over steel because of the substantial weight advantages. Aluminum is about one-third the weight of steel. Use of aluminum resulted in the Insight white body weighing nearly 50 percent less than the current Civic Hatchback white body.

Yet, aluminum presents many challenges. As a material, aluminum is generally less rigid. Aluminum tears easily when stretched, during the stamping of complex shapes. So, sometimes this would require a split into several parts. Thus, this process would need more parts and result in more dies, welding processes and jigs – which also increases the cost.

As you know, the Acura NSX -- designed as a real sports car with a mid-ship engine -- was the world's first all-aluminum production car. It was a breakthrough when it was introduced in 1990. However, due to the extensive use of costly aluminum stamped parts at a low volume of production -- the price of the NSX is over 70 thousand dollars.

For Insight, our fuel economy target again mandated that we use aluminum. However, our "customer acceptance" target mandated that we meet advanced safety requirements and offer Insight at a reasonable price. There is no law that says environmental vehicles have lower safety standards. Thus, we needed to adopt new technologies to produce Insight -- but to do it cost effectively.

For Insight, the unique aerodynamic design added challenges to the process of shaping aluminum. As you can see, for both the exterior and undercarriage, we focused on achieving the optimum compact aerodynamic form. This unique shape achieves a coefficient of drag of just 0.25.

You may be thinking that Honda already had great experience with aluminum production because of the Acura NSX. And we did benefit from the NSX experience in several areas – especially the outer panel finish and weld quality.

In the area of aluminum outer panels, we learned typical problems, such as the difficulty in maintaining the original shape due to "spring back." Thus, we were able to adopt efficient countermeasures in an early stage of Insight's development.

From the NSX we also developed critical control items that helped Insight achieve high quality in aluminum welding using fewer prototypes and a shorter development process.

Because of these challenges, a critical element of Insight's development was the close working relationship between Honda R&D and our manufacturing operations. The Takanezawa Plant was originally established to produce the NSX. Today, it also builds the S2000 and Insight. In other words, it is a plant dedicated to the production of special low volume products.

To produce Insight at this plant in areas such as aluminum spot welding and arc welding – we were able to utilize the same equipment in the Takanezawa plant as used for NSX. But even here we had to add additional equipment for larger volume production for Insight and S2000. We also made modifications in weld and paint to increase flexibility between aluminum and steel bodies, like S2000, to minimize any additional investment.

As I mentioned before, aluminum presents unique challenges to manufacturing operations such as stamping, due to its formability. However, the softness of the metal also offers a greater variety of forming methods – from extrusion to die-casting and sheet-forming. And Insight employed each of these methods.

Comparing the use of aluminum on NSX and Insight, you can see that with the NSX, by far most of the aluminum is sheet material. However, with Insight, more than 40 percent of the aluminum is either extruded or die-cast material.

Extruded material is utilized extensively in the basic frame structure because it can more easily be formed into complex shapes. This provides more rigidity and strength. In this way, creating tube-shaped elements did not require welding together stamped sub-elements. As a result, we could create many one-piece sections for maximum rigidity.

We also increased the use of die-cast aluminum for greater rigidity. Use of die-cast parts was critical to enabling us to use various extruded frame sections – helping connect the extruded parts more rigidly and with fewer parts. As you can see, the joints at each of the four corners of the cabin are die cast and double as suspension supporting elements.

We also employed thixotropic die cast material for the first time in the world for the frame of an automobile. We used this thixo die cast for the rear outrigger, which doubles as the rear suspension pick up point. Thixo die casting involves semi-molten aluminum injected into a mold. This precisely controlled process provides a consistent and stable thin shape – resulting in both higher quality and weight reduction.

This provided two significant benefits. First, the more rigid body improved safety performance. Second, it achieved a major cost reduction by avoiding stamping dies, reducing the overall number of parts, and eliminating a number of weld points.

The general perception is that a small car with a lightweight aluminum body will be less rigid and less crash-worthy than a steel frame and body. However, with Insight we were able to achieve advanced safety standards. Use of extruded aluminum is a primary factor. Extruded production has the advantage of producing frame parts with different degrees of thickness within a single part. This was an advantage for both higher safety performance and a reduction in weight.

Further, by directly connecting extruded and die-cast parts together, we achieved a more rigid cabin – creating a safety space for a driver and a passenger. Finally, using many extruded and die-cast parts means fewer parts to connect and a stronger connection as well.

The cabin frame structure is the core of passenger protection. The large-section extruded materials that compose the cabin and the highly rigid die cast joints form a strong foundation. This deforms only minimally in a collision.

The frame surrounding the cabin also uses extruded materials to control the force of impact. This absorbs and disperses energy from front, rear and side impacts. A key aspect to this safety performance is the design of the extruded material. As you can see, we were able to use a variety of shapes and of different thickness for the body frame sections.

For instance, a hexagonal design with reinforcing ribs is employed in the front side frame structure. In the first stage of a collision, the tips of this hexagonal design absorb collision energy -- collapsing in accordion fashion.

The frame's rear portion is connected by a cast joint and has a thicker, curved shape. In the second stage, this section bends. This controls the impact energy and reduces cabin deformation and the energy that reaches passengers.

Further, the lightweight, hexagonal sectional construction of the front side frame provides for space efficient, energy-absorbing characteristics. Therefore we were able to create a more compact engine room – and a shorter nose, without sacrificing safety performance.

Use of extruded material also helped create a more simple, yet rigid cabin. Three extruded cross members connect with the side sill, center pillar and rear floor frame to achieve side impact protection and protect the cabin. The cross sectional design of the extruded rear floor frame also absorbs rear impact energy in similar way to one for the front. And the unique H-shaped torsion beam rear suspension supports the rear floor frame by splitting the energy to each side sill – to minimize cabin deformation.

Using extruded aluminum for the rear floor frame and roof side rails required new three-dimensional bending technology. Earlier, I mentioned that the aerodynamic design increased our challenge. New bending technology was the most effective way to achieve a simple aluminum body structure with a high degree of rigidity in this improved aerodynamic shape – all at a lower cost.

The bending equipment was developed and manufactured by Honda Engineering – our independent production engineering company that develops tooling and equipment. They developed the bending technology using an original CAE program which links to product design data. The goal was to better predict bending limitations and to optimize material thickness at various points in each aluminum section.

The simulation technology using this CAE program was co-developed by Honda Engineering and Honda R&D at the trial stage to simulate wrinkles in extruded frames. This helped determine how to bend frames without wrinkles. It also helped cut costs by reducing the number of trial parts.

The second program addressed the need to maintain a consistent bending shape in a mass production environment. Initially it was difficult to maintain consistency in the shape of the 3-D frames, even with the exact same action of the bender. Using the CAE program with data on the inconsistencies, the bending machine was programmed to make adjustments each time it bends frames. This led to more consistent quality performance.

During the bending process, the aluminum frame is passed through a three-dimensionally controlled mold. Due to the CAE program, the extruded frame is shaped into even the most subtle curves with great precision. This refined bending equipment is indispensable for manufacturing a unique, state of the art aluminum body. With a manufacturing accuracy of five times that of the ordinary process, we are able to complete aluminum parts manufacturing without requiring a finishing process. This saves time and reduces the investment cost by more than 50 percent.

Viewed together, these new aluminum production technologies helped us achieve a number of important results:

  • White body structure weight is down 47% compared to the current Civic 3-door. This puts Insight at an overall weight of just 162 kilograms.
  • An overall reduction in the number of parts and welds compared to the NSX. For Insight, we are using 15 percent fewer parts and 24 percent fewer welds.
  • Insight bending rigidity is up 13 percent versus the current Civic 3-door; and torsional rigidity is up 38 percent versus Civic.
  • And, overall, by reducing the number of dies, parts and welds, we were able to reduce the white body production cost by more than half versus NSX.

Importantly, the impact of these achievements can all be found in the marketplace. Insight is a breakthrough environmental vehicle, achieving an EPA record best fuel economy of 70 highway and 61 city. At the same time, it meets the ULEV emissions standard. But to experience these environmental benefits, our customers do not have to compromise a desire for safety. Insight was developed to achieve a 4-star performance in NCAP, a 4-star in SINCAP and a good rating by IIHS for offset crash performance.

Of course, the greatest environmental technologies in the world will do nothing for society if the customer will not buy them.

This is why we are happy and proud to say that Insight has demonstrated outstanding sales in this its first year on the market. Through July, American Honda has sold more than 2-thousand units. Based on this success, Honda has increased its annual U.S. sales forecast from 4-thousand units to 65-hundred units.

Next year, based on the development of Insight, we will begin expanding gas-electric hybrid technology to mass market vehicles. So, the challenge of creating environmental technologies is not over. However, my greatest challenge – this presentation – is now complete. And I would like to thank you for your patience and your attention. Thank you.

Kazuhiko Tsunoda, Honda R&D Co., Ltd.

UM-OSAT Automotive Management Briefing Seminar
Traverse City, MI August 2000

 

 
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