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Casting Module 2, Engine Plant, Suzuka Factory, Honda Motor Co., Ltd.

Roughly half of the industrial waste that came out of Suzuka Factory was spent foundry sand.

Roughly half of the industrial waste that came out of Suzuka Factory was spent foundry sand.

Associates begin joint research and development with Wako R&D Center*

 Metal mold casting was one alternative to sand metal casting that associates explored. In fact, Honda had successfully switched from sand to metal mold casting for other parts in the past. However, the large empty space in the middle of the cylinder sleeves made sand the only material suitable for molding. Producing cylinder sleeves by metal mold casting alone proved nearly impossible.
 "That's when I heard that the Wako R&D Center was conducting research on a method for manufacturing cylinder sleeves called centrifugal casting," said Furukawa.
 Centrifugal casting is an old technology that has been used since the 1920s, primarily to manufacture pipes for oil pipelines. In this method, molten metal is poured into a metal tube (metal mold) that is spun at a high speed. Spinning causes the molten metal to stick to the inner surface of the tube. Once the metal has cooled and hardened, it is pulled out of the mold, producing a tube one size smaller than the mold.
 Engine Management Department engineer Toshihiro Nishiwaki, who would later take part in developing the Spincast method, looked back on the time when he first learned about centrifugal casting.
 "The Wako R&D Center was conducting this research to reduce industrial waste (spent sand) as part of an environmental responsibility initiative. Meanwhile, all of us working in casting at Suzuka Factory were strongly in favor of getting rid of sand mold casting, since working conditions were so harsh. So we got together and proposed a joint research project to the Wako R&D Center."
*Wako R&D Center: Automobile R&D Center, Wako, Honda R&D Co., Ltd.

Centrifugal casting method

Centrifugal casting method

Toshihiro Nishiwaki, Engineer, Engine Management Department, Suzuka Factory

Toshihiro Nishiwaki, Engineer, Engine Management Department, Suzuka Factory

The sand-cast cylinder sleeve used before introduction of the Spincast method

The sand-cast cylinder sleeve used before introduction of the Spincast method

Associates needed a centrifugal casting method that could produce perfect, quality-added cylinders at scale.

 Centrifugal casting was originally used to make large pipelines. Applying this technology to cylinder sleeve production would require a major improvement in the level of precision of current methods. The objective of the joint research project was to develop a centrifugal casting technology that could make perfectly round cylinders—and at production scale.
 They began their research by making cylinders 40-cm long, and then tested their methods at lengths of 2 m based on the need to scale upward. Theoretically, the process they designed was to make 2-meter-long tubes that could then be cut into a dozen or so cylinder sleeves. However, they ran into a several problems in the switch to 2 meters.
 "If the metal mold was just slightly off, it would vibrate and make this really loud noise when we spun it on the rollers. I can still remember being scared that the mold might come flying at me," said Furukawa. "Another problem was that different spinning speeds of the mold and pouring rates of the liquid metal would create different thicknesses of the cylinder across the 2 meters. This was less of a problem with the calculations and more about finding the right balance through trial and error." Their only option was to take time solving these problems one by one. Yet when they finally seemed to have solved them all, a new problem emerged.
 "We couldn't pull the cylinder out of the mold," said Nishiwaki, "no matter how hard we hit it with a hammer. We broke several hammers from hitting it so hard."
 When casting at a length of 2 meters, the cylinder stuck to the mold after it cooled. Trying to pull it out before it hardened resulted in them breaking it off half way.
 "The only way to do it was to pinpoint the exact moment when it was hard enough to pull out," said Furukawa. "This was also something we couldn't calculate. We just had to try it over and over again. Over time, by looking inside the mold and watching the change in temperature, we found a point when it was just hard enough to pull out."
 At last, the group arrived at a method for casting 2-meter-long cylinders accurately and consistently.
 "The exterior surface of the cylinder sleeves we made with sand molds had rings of depressions around them," said Nishiwaki. "This helped keep the cylinder sleeves locked in place when inserting them in the cylinder block, since the texture of the surfaces would grab each other. The larger surface area also helped to disperse heat. The last problem we ran into was how to create an equal or better surface texture with the centrifugal casting method."
 Molding a texture on the finished cylinder sleeve required imprinting a texture on the metal mold. But the interlocking of surfaces between the cylinder and the mold would keep the cylinder from sliding out. The development team scratched their heads at this last hurdle.

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