Selection of furnaces and various types of furnaces (UNIT2)
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This document discusses different types of furnaces used for melting metals. It begins by outlining factors to consider when selecting a furnace, such as initial cost, fuel cost, metal properties, and production needs. It then classifies furnaces according to the metal they melt - for gray cast iron, steel, and non-ferrous metals. Specific furnace types are listed for each metal. The document focuses on cupola furnaces next, describing their widespread use for iron melting and characteristics like their water-cooled cylindrical design lined with refractory material. Construction details of cupola furnaces are provided.
Selection of furnaces and various types of furnaces (UNIT2)
- 1. Selection of Furnaces and various types of Furnaces Prepared by Ankit saxena Assistant Professor ADGITM, NEW DELHI
- 2. Selection of melting furnaces The selection of a foundry furnace depends upon the following factors: i. Initial cost of the furnace ii. Fuel cost iii. Kind of metal or alloy to be melted iv. Melting and pouring temperature of the metal to be cast v. Quantity of metal to be melted vi. Cost of furnace repair and maintenance vii. Cost of melting per unit weight of the metal viii. Chances of metal to absorb impurities during melting ix. Quantity of the finished product desired
- 3. Furnaces can also be classified according to the molten metal 1. Gray Cast Iron i. Cupola ii. Air furnace iii. Rotary furnace iv. Electric arc furnace 2. Steel i. Open hearth furnace. ii. Electric furnace. Arc furnace High frequency induction furnace 3. Non-ferrous metals i. Crucible furnaces (Al ,Cu) Pit type Tilting type Non-tilting or bale out type Electric resistance type (CU) ii. Pot furnaces (fuel fired) (Mg & Al) Stationary Tilting iii. Reverberatory furnaces (fuel fired ) (Al & Cu) Stationary Tilting iv. Rotary furnaces Fuel fired Electrically heated v. Induction furnaces (Al & Cu) Low frequency High frequency vi. Electric Arc furnaces (Cu)
- 4. CUPOLA FURNACE i. For many years, the cupola was the primary method of melting used in iron foundries. ii. The cupola furnace has several unique characteristics which are responsible for its widespread use as a melting unit for cast iron. iii. Cupola furnace is employed for melting scrap metal or pig iron for production of various cast irons. It is also used for production of nodular and malleable cast iron. It is available in good varying sizes. The main considerations in selection of cupolas are melting capacity, diameter of shell without lining or with lining, spark arrester. Shape A typical cupola melting furnace consists of a water-cooled vertical cylinder which is lined with refractory material.
- 5. i. Construction ii. The construction of a conventional cupola consists of a vertical steel shell which is lined with a refractory brick. iii. The charge is introduced into the furnace body by means of an opening approximately half way up the vertical shaft. iv. The charge consists of alternate layers of the metal to be melted, coke fuel and limestone flux. v. The fuel is burnt in air which is introduced through tuyeres positioned above the hearth. The hot gases generated in the lower part of the shaft ascend and preheat the descending charge.