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Special Sands

HA Special Sands

The term “special sand” covers all industrial minerals (except quartz sand) commonly used in foundries as moulding material for the manufacture of cores and moulds/dies.

Special sands include natural mineral sands, sintering and melting products produced in granular form or turned into granular form by breaking, grinding and grading processes, or inorganic mineral sands produced by other physical-chemical methods.

Special sands are different from quartz sand, particularly as regards their significantly lower thermal expansion behaviour within the temperature range of 20 – 600°C, their heat conductivity, refractoriness, and other physical characteristics.

Strengths of HA special sands

Special sands are used instead of quartz sand for coremaking and mouldmaking because they are characterized by better physical-chemical properties.

In consideration of the casting properties to be achieved, the individual advantages of a special sand can be used to:

  • avoid sand expansion defects, especially finning/veining
     
  • avoid the addition of gas-forming ingredients
     
  • reduce the core weight

  • avoid metal penetration

  • increase the flowability of the sand
  • avoid a mould-metal interface reaction

  • control the formation of microstructure

  • produce thin-walled castings

 

 

Special sands for all requirements

 

 

Kerphalite

The strengths of Kerphalite
 

  • Suitable for all casting types
  • Low coefficient of linear expansion
  • Can be used in the following processes: PUR-Cold-Box, SO2-Cold-Box and shell moulding, cold resin, resole-CO2 /MF, resol/ester, bentonite
  • Ideally suited for high thermal stress

 

 

Characteristics 

 

  • Natural, processed mineral = Andalusite
  • Aluminium silicate
  • Solid density of 3.13 g/cm³
  • Pouring density of approx. 1.6 g/cm³
  • Refractoriness: Seger Cone >36 
  • reference temperature:  >1800°C
  • Linear expansion α 20 – 600 °C = 6.5
  • AFS   60 ± 5 | MK  0,23 mm

J-Sand

The strengths of J-Sand

 
  • Suitable for all types of castings (except steel casting)
  • Special base sand
  • Suitable for PUR-Cold-Box, SO2-Cold-Box, shell moulding, resole-CO2 /MF
  • 50% lower coefficient of linear expansion than quartz sand
  • Optional selection of the ideal classification for your specific applications

 

Characteristics
 

  • Natural mineral and sand mixture
  • Approx. 49 % feldspar + 48 % quartz
  • Solid density of 2,66 g/cm³
  • Pouring density of approx. 1,5 g/cm³
  • Refractoriness: Seger Cone 17 
  • reference temperature: 1500 °C
  • Linear expansion α 20 - 600 °C = 13,7
  • 0,17 / 0,20 / 0,26 / 0,28 / 0,33 (± 0,03 mm)

 

M-Sand

The strengths of M-Sand

 

  • Suitable for all casting types
  • Suitable for the following processes: PUR-Cold-Box and SO2-Cold-Box, cold resin, resole-CO2 /MF, resole/ester
  • Very low coefficient of linear expansion
  • Ideally suited for extreme thermal stress
     

 

Characteristics 

 

  • Melt product = fused mullite
  • Aluminosilicate
  • Solid density of 3,11 g/cm³
  • Pouring density of approx. 1,6 g/cm³
  • Refractoriness: Seger Cone > 36 
  • reference temperature:  > 1800 °C
  • Linear expansion α 20 - 600 °C = 4,5
  • AFS 60 ± 5 | MK = 0,23 (± 0,02 mm)

 

Cerabeads

The strengths of Cerabeads
 

  • Suitable for all types of castings
  • Suitable for the following processes: PUR-Cold-Box, SO2-Cold-Box, shell moulding, cold resin, resole-CO2 /MF, resole/ester
  • Low coefficient of linear expansion
  • Ideally suited for extreme thermal stress
  • Optional selection of the ideal classification for your specific applications

 

Characteristics 

 

  • Synthetic sand = sintered mullite
  • Aluminosilicate ( > 80% mullite)
  • Solid density of 2,86 g/cm³
  • Pouring density of approx. 1,6 g/cm³
  • Refractoriness: Seger Cone >36 
  • reference temperature:  = 1800 °C
  • Linear expansion α 20 - 600 °C = 4,0
  • AFS 42, 65 und 107 | MK 0,38 / 0,23 / 0,11 (± 0,02 mm)

 

Bauxit-Sand

Areas of application

 

Cold-Box Process | Iron casting

Water jackets for crankcases, cylinder heads, turbines and exhaust manifolds

Cold-Box Process | Al-Casting

Water jackets for crankcases and cylinder heads

Inorganic | Al-Casting

Water jackets for electric drive trains

 

Characteristics

 

  • Melt product = melt bauxite
  • ≥ 72 % Al2O3 + SiO2, Fe2O3, TiO2
  • Solid density of 3,3 g/cm³
  • Pouring density of approx.  2,0 g/cm³
  • Refractoriness: Seger Cone 36 
  • reference temperature: 1800 °C
  • Linear expansion α 20 - 600 °C = 7,2
  • AFS 55 ± 5 / 65 ± 5
  • MK 0,27 / 0,23 (± 0,03 mm)

Foundry characteristics and applications of HA special sands

 

 

The main difference between HA special sands and silica sand is the significantly lower coefficient of linear expansion and significantly lower thermal expansion behaviour during the casting process.

Furthermore, HA special sands are the ideal moulding material for core production:

  • High sintering and melting points (except J-sand)
  • Compatibility with all binders used for core production
  • High cold-strength properties of the moulding material
  • High hot strength properties of the moulding material (except J-sand)
  • Available in a range of different classifications

Many years of experience at Hüttenes-Albertus have shown that the use of HA special sands depends on the complexity of the respective casting, the metal used for the casting, the susceptibility to veining, the casting temperature and the binder system.

Application examples

The use of J-sand for PUR Cold-Box core production allows automotive series castings to be produced without sand expansion defects, thereby avoiding the need to add gas and odour-forming additives.

For castings manufactured under extreme thermal stresses with a high tendency to veining, we recommend the use of Kerphalite KF, Cerabeads or M-Sand for PUR-Cold-Box. The high-temperature properties of these HA special sands also ensure that they can be used as a basic moulding material for steel castings.

The thermal expansion of shell moulding material tends towards zero when using quartz-special sand mixtures. When using 100% Kerphalite KF and Cerabeads, shrinkage of the shell core occurs. In sensitive hydraulic and automotive casting, complex cores are produced with coated HA special sands, which guarantee flawless castings close to final dimensions.

Hüttenes-Albertus markets its shell moulding sands containing Cerabeads under the brand name Keracron®.

Your contact

Dipl.-Ing.

Martin Dahlmann

Regional Product Manager EMEA Shell Moulding Process, Special Sands

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Dipl.-Chem.

Emma Caputo

Product Manager Shell Moulding Process, Special Sands and Industrial Resins

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