The problem of foundry production is manufacture of billets and machine parts by pouring fused metal into a casting mould, whose cavity has the shape of the billet. After crystallization the solid metal keeps the shape of the cavity. The billets are called castings. Scheme of casting process Molten metal Mould Casting Melting furnace Method of Casting Foundry equipment Pouring Moulding materials Finished casting Knock-out – Cleaning – Sand blowing or steel grit blasting – Fettling – Heat treatmen

The cast alloys should possess the good running quality, small linear and volume shrinkage, no susceptibility to cracking and formation of gas voids and porosity. Pouring fused metal into a casting mould Case made by casting

Sequence of casting manufacture: а – part drawing; b – casting drawing; c – pattern; d – core; е – core box; f – complete mould for manufacture of casting Designations: 1 – allowances for machining; 2 – tapers; 3 – fillets of angles; 4 – conic pins; 5, 6 – core marks

Manufacture of shell mould : 1 – pattern plate; 2 – bunker; 3 – moulding mix (quartz sand and thermosetting resin); 4 – shell 20 mm thickness Advantages of the process: – pinpoint accuracy of the sizes (allowances the tithes of millimeter); – smoothness of the surface; – high gas permeability of moulds; – little expenses for moulding materials; – applied to any alloys. Limitation of this method: – resin is expensive material; – toxic gases are emitted during casting; – weight of castings is limited by 100 kg approximately (mould cannot hold the big weight of the liquid metal. Special methods of casting а b c

a b c d e Investment casting: a – casting; b – fusible substance in metal mould; c – pattern ; d – block of patterns; e – ceramic shell 8 mm thickness Advantages of the process: – high accuracy of the sizes (allowances 1/100-th parts of mm); – castings do not demand machining, except grinding; – saving metal (the general gating system for a set of castings); – applied for small complex shape items, made of expensive alloys. Limitation of this method: – high labour input of manufacturing ; – high costs of castings (10 times higher than in sand casting). Special methods of casting Industrial and art castings