Foundry
Foundry processes and furnace technologies for metal casting
A foundry is an industrial facility dedicated to melting and casting metals into specific shapes, components or engineering products. The core element of any foundry operation is the melting furnace, though furnace technologies have advanced significantly over time. Each furnace type has distinct thermal characteristics, energy requirements and suitability for various metal alloys.
Cupola furnaces for cast iron melting
The cupola furnace is a vertical shaft furnace historically used for melting cast iron. Although its usage has declined in modern foundry practice, it remains an important reference in traditional ferrous metallurgy. The furnace features a cylindrical steel shell lined with refractory brick to withstand high thermal loads and chemical attack.
Metallic charge materials, along with coke and fluxes, are layered into the shaft through a charging door positioned mid-height. Preheated air is introduced via tuyeres near the base to initiate combustion. As the charge descends, it melts and accumulates at the base, where molten iron is collected on a sand bed and tapped off through a spout. While cupolas offer high throughput, they are less efficient and environmentally compliant than newer systems.
Induction furnace technology for precision melting
Induction furnaces are widely used in modern foundries for their energy efficiency, precise temperature control, and cleaner operation. These furnaces use electromagnetic induction to generate heat within a crucible containing the metal charge. Surrounding the crucible are water-cooled copper coils that produce an alternating magnetic field, inducing eddy currents and heating the metal internally.
Induction furnaces are suitable for melting a wide range of ferrous and non-ferrous metals. They are quieter, cleaner, and faster than traditional cupolas, with superior control over melt temperature and chemistry. However, they offer limited refining capabilities, and minor oxidation losses may occur during operation.
Reverberatory furnaces in non-ferrous metal casting
The reverberatory furnace is a type of open-hearth furnace primarily used for melting non-ferrous metals, especially aluminium, copper, bronze, and brass. In this design, the molten charge does not come into direct contact with the combustion flame. Instead, heat is transferred via radiation and convection from combustion gases that travel over the surface of the metal bath before exiting through the flue.
While largely replaced in primary melting operations, reverberatory furnaces remain in use for melting scrap aluminium for die casting and secondary refining. They are valued for their capacity and ability to process low-grade input material, though thermal efficiency is relatively lower than in closed melting systems.
Molten metal handling systems: ladles and pouring systems
In addition to the furnace, foundries require specialised molten metal handling systems to transport the melt safely and efficiently to the pouring station or mould. These systems revolve around ladles, which are metallurgical vessels made from steel and lined with high-performance refractory linings.
Ladle configurations vary by application. Basic lip-pour ladles are used in small workshops, while large teapot spout or bottom-pour ladles are preferred in industrial operations. Bottom-pour ladles help reduce the inclusion of slag or dross by allowing cleaner metal from the lower zones of the bath to flow first. All ladles are engineered to meet high standards of thermal insulation, mechanical integrity and operator safety.