Foundry moulding process:
1. Gravity Casting: Sand Casting, Hard Casting. The molten metal is poured into the cavity by the gravity of the metal itself.
2. Pressure casting: low pressure casting, high pressure casting. Molten metal is instantaneously pressed into the casting cavity by additional pressure.
(1) The preparation of casting mould (making liquid metal a container for solid casting) can be divided into sand mould, metal mould, ceramic mould, mud mould and graphite mould according to the materials used, and can be divided into disposable mould, semi-permanent mould and permanent mould according to the number of times used. The quality of casting preparation is the main factor affecting the quality of casting.
(2) Melting and pouring of casting metals, casting metals (casting alloys) mainly include various kinds of cast iron, cast steel and cast non-ferrous metals and alloys;
(3) Casting treatment and inspection, including removal of foreign bodies from core and surface of castings, removal of gating risers, relief burrs and drapes, heat treatment, shaping, rust prevention and rough processing.
Casting technology can be divided into three basic parts, namely, casting metal preparation, casting preparation and casting treatment. Foundry metal refers to the metal material used in casting production. It is an alloy composed of one kind of metal element and other metal or non-metal elements. It is customarily called casting alloy, mainly cast iron, cast steel and cast non-ferrous alloy.
Metal smelting is not only a simple melting process, but also a smelting process, so that the metal poured into the mold meets the expected requirements in terms of temperature, chemical composition and purity. Therefore, in the smelting process, all kinds of inspection and testing should be carried out for the purpose of controlling the quality, and the liquid metal can be allowed to pour only after reaching the specified targets. Sometimes, in order to meet higher requirements, the liquid metal must be treated outside the furnace after it is discharged, such as desulfurization, vacuum degassing, refining outside the furnace, inoculation or deterioration. Commonly used equipment for smelting metals are cupola, electric arc furnace, induction furnace, resistance furnace, reverberatory furnace, etc.