Molten Metal Systems


Sigma crucibles are premium quality hybrid ceramic bonded clay graphite crucibles with a high silicon carbide and graphite content that is manufactured through an advanced iso-static pressing process. As a consequence of user-related innovative developments, optimised Sigma variants are available.


Sigma E is intended for aluminium and aluminium alloys as well as for zinc and zinc alloys melting in fuel-fired and electric furnaces.

Sigma HT is intended for melting copper-based alloys in fuel furnaces.

BNI, due to its shape, provides high resistance to flame attack and offers enhanced performance in heavy duty applications such as aluminium scrap melting and other fuel fired applications.  

Sigma Typical Metal Casting Temperature 

Sigma E 450°C - 900°C (842°F - 1652°F).

Sigma HT 900°C - 1600°C (1652°F - 2912°F). 

BNI 700°C - 1400°C (1292°F - 2552°F).

Performance Characteristics

  • High erosion resistance at elevated temperatures leading to longer product life.
  • Faster melting through consistently high thermal conductivity, resulting in better energy efficiency.
  • Non wettability due to high product density and use of special quality graphite in manufacturing.
  • Consistent performance and repeatability.
  • High mechanical strength.
  • Good resistance to chemical attack.


Sigma HT crucibles are finished with a black coloured coating and the models are suffixed with the letters 'HT'.

Sigma E crucibles are finished with a grey coloured coating.

BNI crucibles are finished with a grey coloured coating and models are prefixed with the letters 'BNI'.

Pattern Range

Sigma crucibles are available in a comprehensive range of shapes and sizes to suit most end user requirements.

For available sizes and shapes click here.