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Spotlight

Extended service life, perfect casting results – die coatings from HA

The French SICTA Group is one of the world’s leading automobile industrial suppliers and manufactures components for a range of companies, including Mercedes, BMW, Audi and Porsche. SICTA Group’s Hungarian subsidiary uses gravity die casting to cast turbo charger housings from aluminium-silicon alloys. For many years, the company has been successfully using HA products, including resin coated sand and Cold-Box binder systems.

In 2020, SICTA KFT. (Hungary) successfully completed a series of tests on HA’s die coatings. Having chosen products from HA because they meet SICTA’s specific requirement profiles, the tests confirmed that the HA die coatings significantly extend the service life of casting tools, thereby guaranteeing more efficient production processes.

Extending the service life of casting dies ensures better casting results and reduces the cleaning workload for the dies.

The procedure

  • Foundry employees received special training to ensure they understood the entire coating application process and each of the individual process steps
  • All of the die parts were thoroughly cleaned, e.g., by blasting with dry ice, corundum or other blasting media
  • The die was uniformly preheated to a temperature of approx. 250°C and the temperature was accurately measured
  • The die coating was diluted with water and uniformly mixed to achieve a ready-to-spray die coating
  • A suitable spray gun was used to spray the coating on the die in thin layers, ensuring the correct spraying pressure and distance

The following trial conducted in the foundry confirmed that the service life of the die was instantly significantly improved:

The dies were first coated with a thin layer of HA KS 92 die coating as a base coating. HA Eco Coat 183 was then applied as a working coating in the contour area. HA Eco Coat 183 has good insulation properties and contains added graphite to make it easier to remove the casting from the die.

In the runner and feeder area, a coating of high insulation, HA KS 81, was applied to the base coating to ensure optimum mould filling with little temperature losses, extend the feeding period and achieve shrinkage-free castings.

The solution

By using a base coating that sticks very well to the die steel and a second layer of working coating, which can be selected accordingly to achieve the desired insulation effect, the service life of the die coating can be significantly extended.

Another advantage of this system is that the variations in the colours of the base and working coatings make it easy to visually detect wear on the working coating before the molten aluminium comes into direct contact with the die steel. This prevents excessive or premature wear on the die.

Further tests over the next few days revealed that the service life of the die coating was approximately twice as long compared to standard die coatings. Further optimisations of the process achieved an even longer service life, which allowed continuous casting of a die over a period of up to 20 shifts without reworking the die.

Subsequent tests with die coatings from three other suppliers achieved only half the service life at best.

Further development

Meanwhile, Sicta has also been using the newly developed, extremely highly insulating HA Eco Coat 186 die coating. This coating has been specially designed for gating, runner and feeder areas. It is sprayed on and used in this setting where otherwise die coatings would have to be applied very thickly by brushing. This brush-on method drastically reduces die service life.

The proven solutions, which are precisely tailored to the requirements of the foundry, have played a successful role in optimising the casting process.

SICTA is by no means the only customer to have successfully tested and used die coatings from HA. In order to achieve optimum casting results and the highest possible functionality, HA’s die coatings are always selected to each foundry’s specific applications and developed to perfectly match each customer’s precise requirements.

 

Your contact person:
Dirk Peppinghaus
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