When Less Can Be More
Minimal lubrication in gear case casting production saves money and the environment
KODA AUTO has introduced a technological innovation in the die-casting process for MQ 200 gearbox housing production in the form of lubricating the casting mould with the minimum amount of release agent. The innovation has quickly proved its worth and succeeded in meeting virtually all of the project’s objectives, including reducing the environmental impact of production. The introduction of the new process dramatically reduces not only the consumption of the release agent as a lubricant but also water and compressed air for mould blowing. At the same time, the quality of the parts was improved, maintenance costs of the die casting tools were reduced, and productivity of the gearbox housing production was increased due to (in part) an acceleration of the entire casting cycle. “The only thing we haven’t verified in practice yet is the life span of the moulds. We expect this to be higher as well; however, compared with the previous technology, we haven’t reached a sufficient number of cycles to confirm this yet”, says Milan Adamec from PKG/3 – Forge and Foundry Technology. Therefore, this is another potential of this project.
Overall, the new minimum lubrication technology speeded up the production cycle by 13 percent and reduced mould cleaning needs by half.
Benefits for nature
Lubrication technology has changed completely. In the conventional process used before, the release agent (and also lubricant) was mixed with water, and 6 litres of this mixture were used per cycle. Now, the spray nozzles dispense the release agent in aerosol form on the inner parts of the mould in the order of millilitres (24 ml per cycle). Only some parts of the mould then need to be aftercooled by being sprayed with water. The amount of water needed per cycle is now about half a litre. Therefore, the new technology saves 5.5 litres of water per cycle, which previously created wastewater that had to be treated.
Because less liquid is used for mould aftercooling, the quality of the final castings has been improved since the evaporating cooling water was causing minor porosity in the castings. Owing to the optimisation of the mould’s internal cooling parameters, the new technology resulted in a more even temperature distribution on the mould surface, which also contributed to better quality. “At the same time, the aluminium doesn’t stick to the mould as much, which means less mould maintenance and fewer cleaning demands”, says M. Adamec. All of these benefits have reduced the frequency of casting machine stops, resulting in fewer so-called run-in parts needing to be recycled. The new technology still has potential for further development. “At the end of the tools’ lives, we can prepare new tools with internal cooling designed for the new minimum lubrication method and, thus, completely eliminate external water aftercooling from the process”, concludes M. Adamec. ED