Blacksmithing on the Farm - With Information on the Materials, Tools and Methods of the Blacksmith

MANUFACTURE OF IRON AND STEEL

159. Preliminary. There is quite as great need on the farm and in the house for a knowledge of metalwork and facilities to carry it on as for woodwork and cement work. The house-owner and home-maker is more independent if he can do the ordinary things about the home premises which demand the use of metalworking tools for the simpler constructions and repairs.

Under the general head metalwork, we shall consider, under separate parts, the following special branches of metalwork: Forging, Sheet-metalwork, and Farm Machinery Repair and Adjustment.

Under the sub-heads given above, the first will deal chiefly with steel, wrought iron or cast iron, while under the second, tin, zinc or lead, or sheet iron, will be the material handled.

160. Iron Ore. The commercial varieties of iron are pig iron, wrought iron and steel. Iron is found in the ground in natural deposits as ore, which consists of metal imbedded in mineral and extraneous matter of no value. If the ore contains 50 per cent or more of metal, it is called rich. It cannot be worked commercially with profit if it contains less than 30 per cent of metal. The valuable ores are oxides, hydrates or carbonates of iron. Ores appearing as sulphides are poor, as it is difficult to remove the sulphur. However, weathering ore—allowing it to stand in the open—will change sulphides to sulphates, which are largely dissolved out by rain.

One of the richest ores is magnetite, or black ore, which, when pure, contains 72.4 per cent iron and 27.6 per cent oxygen. Hematite, or red ore, when pure, contains 70 per cent iron and 30 per cent oxygen.

161. Pig Iron is made by crushing ore to uniform size and heating it in a blast furnace until it can be drawn off at the bottom in a molten condition. The blast furnace is a long, vertical cylindrical shaft which is fed from the top with ore, fuel or flux. Air under pressure is introduced at the bottom for purposes of combustion. The metal when molten is drawn off at the bottom, usually twice during twenty-four hours, and run into sand molds or iron chilled molds to form pigs of cast iron. Cast iron has 4 or 5 per cent or impurities such as carbon, sulphur, phosphorus, manganese and silicon. The amount of carbon present determines whether the iron is gray or white. If the greater part of the carbon is free as graphite, the iron is known as gray. If the greater amount of carbon present is combined, the iron is known as white. White iron, or iron with low combined carbon, is soft.

162. Wrought Iron is pure carbonless iron produced in a pasty condition. It is the converse of cast