Mechanisation of foundries is necessary, where permitted, (depending on the quantity and type of production) in order to improve the working conditions in foundry, increased production and quality of casting lowering down the cost, elimination of laborious manual operations like preparation of sand, moulds and various other material handling operations.
Mechanisation can be applied to preparation of sand moulds, cores, transporting sand, moulds and molten metal etc. It is best suited where a repetitive work and mass production of small size parts is involved.
Materials handling mechanisation increases efficiency, saves lot of man-hours, keeps production costs low, promotes safety of personnel and reduces damage. The material (sand, flasks, patterns, etc.) are moved automatically at a fast speed.
Heavy-lifting and laborious operations are done by machines. Given floor space is utilised in optimal way, dust nuisance is minimised, and castings with closer dimensional tolerances and with fewer defects are produced.
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Mechanical equipment for sand preparation comprises of magnetic separator (to separate iron pieces, wire nails, iron shots etc.), gyratory riddle (which removes pieces of dry sand cores, hard lumps etc.), rotary sand kicker (which straddles long heaps of sand, previously moistened with water, and mixes the mass with vigorously rotating blades), sand muller (which distributes the various ingredients of sand to make homogeneous mixture), sand aerator (which separates sand grains by whirling it at high speed by an impeller so that each grain can flow freely and smoothly in the direction of ramming), reclamation units (which make used sand fit for reuse after some treatment on it and using some additives). Use of fume and dust extraction equipment is essential in mechanised foundries at screens, chipping or fettling benches, knock out belts, turning point etc.
Large overhead bridge cranes are used to convey all parts on a large floor area. Moulding-sand distribution conveyor belt is used to convey sand from sand-preparation unit to individual sand hoppers, located directly above the moulding machines. For filling sand into flask, the operator pulls a lever and desired amount of sand falls down. Roller conveyor system is used to carry moulds and flasks from one place to other.
Several types of moulding machines (jolting, squeezing, slinging, jolting and squeezing etc.) are used. Use of turn tables (circular revolving table having number of moulding machines) provides highly mechanised system.
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Turntable revolves at a slow speed and several operations are carried out at various stations, each worker doing his predefined work on each station. The operation of melting, pouring of metal is also mechanised to the extent possible. The material handling equipment like belt conveyors, bucket elevators, mono rail conveyors, crane etc. are used for handling sand, cores and core sand, castings, furnace charge etc.
Moulds from the mould production area are conveyed for pouring by either roller conveyors, or pallet conveyor or overhead conveyor. Molten metal may be poured while moulds are in motion, (or mould transported to pouring ladle where metal is poured) and after pouring and cooling, the moulds are conveyed to shake-out operation; the castings removed and transported to fettling shop, and the emptied flasks, moulding boards etc. are turned to the moulding shop.
In pouring of the molten metal, it is brought in ladles from the furnace on a mono-rail type overhead conveyor and is moved in synchronism with mould so that metal can be poured in continuously as the mould is moving.