ABSTRACT
Many of the aspects of workshop technique can only be acquired by experience, by teaching on the spot and by contacts with experienced craftsmen. The materials chiefly used in the shops are metals, and these are divided into those which come from iron and those which do not. The magnetic property of iron alone has conferred incalculable benefits on humanity. Pure iron is a soft metal having a crystalline structure. The size of the crystals in iron and steel depends upon the treatment the metal has received, and in the steel used in the workshop the crystals may vary from 1100 to 20100 mm. The modern method of casting pig iron which has largely superseded the older pig-bed method is to employ a pig-casting machine. Grey iron is a very useful metal in engineering construction. The essential difference between cast iron and steel is in the amount of carbon contained in the constituency of the metal.
