Toyota Motor Corporation (Toyota) has announced that it has jointly developed an innovative aluminium casting technology that improves the plant environment and product functionality, for which it has received the Okochi Memorial Production Prize in the 66th (2019) Okochi Memorial Prize awards.

The award was presented by the Okochi Memorial Foundation, acknowledges remarkable achievements related to research and development, and the application of production engineering, production technology, and production systems annually. Toyota says this marks the first time in three years that it has been awarded the prestigious Okochi Memorial Prize. It is also the 12th Okochi Memorial Prize overall for Toyota.

The Japanese OEM is implementing initiatives to achieve the ‘Plant Zero CO2 Emissions Challenge,’ which is one of the targets in the Toyota Environmental Challenge 2050, announced in 2015. The company says as the electrification of vehicles proceeds, engines will also have to evolve, such as through the use of technologies to achieve high thermal efficiency. For these two reasons, Toyota developed the aluminum casting technology that received this prize.

Manufacturing cylinder head

The OEM says it received this prize for a world-first aluminium casting technology for cylinder heads, which affect the engine performance. The cooling water channels of a cylinder head are normally formed using moulds made from sand and adhesive, known as a core. The technology commonly used to make cores at present employs an organic material called phenolic resin as the adhesive. However, the casting process produces strong odours and smoke, giving rise to the issue of large deodorisation equipment required to deal with the odorous gas by-products.

Structure of cylinder head cooling water channels

On the other hand, the increased cooling capacity of the cylinder head is necessary for improving engine performance, and this requires thinner and more complex cooling water channels. Also, using inorganic material as the adhesive is an effective way of eliminating smoke and odour, but there was previously no method of manufacturing cores that would allow for complicated shapes and reuse of sand.

Using inorganic material
The aluminium casting technology developed by Toyota uses the inorganic material, water glass, which does not cause odours or smoke. Moreover, the company says this world-first technology enables complex shapes to be created and the sand to be reused. Using water glass, which is not subject to thermal degradation, to adhesive the sand has succeeded in reducing odour concentrations during the casting process to 1/100th or less, thereby reducing the investment required in deodorisation equipment.

Also, the action of surfactants creates a mousse-like consistency that improves the flowability of the sand, which enables the creation of thin and complex cooling water channels in the cylinder head. This is contributing significantly to the mass production of new model engines with a thermal efficiency of 41 percent. The temperature at which the sand is processed was also reduced, with the effect of more than halving the CO2 emissions of traditional methods.

Comparison of sand flowability

The company says the cylinder heads made using this technology are currently in use all around the world. Going forward, Toyota will extend this technology both internally and to other companies as well, and will take on new challenges to contribute to the realisation of a sustainable society through efforts to bring about positive effects to the earth and society.