1. Introduction
Induction furnaces are the mainstream equipment for aluminum and copper alloy smelting worldwide. The graphite crucible is the core heat-bearing component directly contacting molten metal. Improper material selection will lead to frequent cracking, metal penetration and high production loss. This paper analyzes material matching rules for aluminum and copper smelting, thermal balance design logic and daily fault elimination methods, for furnace operators and factory purchasing staff.
2. Material selection rules for induction furnace crucibles
Clay graphite crucible: Low cost, large porosity, only fit small intermittent smelting, not recommended for continuous copper melting;
Silicon carbide reinforced graphite crucible: Balanced thermal conductivity, anti-corrosion and anti-oxidation, the standard choice for mass aluminum & copper casting production lines;
High-purity isostatic graphite crucible: Low impurity, low outgassing, only suitable for vacuum induction furnaces, easy to oxidize under air high temperature.
3. Thermal balance design requirements
Induction furnace relies on alternating magnetic field to generate internal heat. The crucible wall thickness must be uniform (tolerance ≤±0.2mm). Too thin walls cause local overheating and crack; overly thick walls reduce thermal efficiency and increase power consumption. For 10-50kg aluminum copper smelting, standard wall thickness is 12-18mm.
4. Daily maintenance & fault troubleshooting
Preheating standard: New crucible heating rate shall not exceed 100℃ per hour;
Regular inspection items: Outer wall oxidation degree, inner wall slag adhesion, bottom crack;
Common faults: Metal leakage caused by porosity, thermal shock crack caused by rapid cooling, oxidation peeling under long-term high temperature.
5. Summary
For atmospheric medium-frequency induction furnaces used for aluminum and copper smelting, SiC composite graphite crucibles are the most cost-effective choice. Standardized preheating and regular maintenance can extend service life by more than 60%.
