RHEOCASTING

Kovolis Hedvikov being one of few foundries in Europe and the only one in the Czech Republic, which has been using and offering a progressive method of casting semisolid metal, Rheocasting.

CO2 emissions must be reduced to minimise the environmental impact of the car industry. One of the one way to reach the required emission levels is to significantly reduce the car mass by integraion of aluminium components. To this end, high integrity casting has to be used on a large scale to provide new advanced aluminium components to the industry.

This is here that the SEED / Swirled Equilibrium Enthalpy Device offers a possibility.

The main Rheocasting characteristics:

  • Primary phase α(Al) formation in shape of globular particles
  • Viscosity is decreasing while shear stress increasing → despite high solid fraction rheological behavior enable filling of die cavity

Advantages

  • high integrity parts suitable for structural applications
  • very low gas porosities
  • considerably reduced shrinkage porosity
  • excellent pressure tightness
  • possible to cast low iron alloys
  • globular structure
    • high elongation
  • fully heat treatable (T5 and T6 (blister-free) ) high pressure die castings
    • high tensile and yield strength after heat treatment
  • weldable parts
  • near net shape, thick and thin-walled castings that require less machining
  • geometrical flexibility
  • possibility to remelt returns

Constrains

  • part design
    • a need of thick ingate
    • a need of cross section equilibrium
  • material
    • use of hypoeutectic alloys with silicon content up to 8%

Parts made by this technology are in a serial production for Stellantis corporation, mounted to engines of Peugeot, Citroen and Opel cars. There were more then 300.000 pcs supplied so far.