This section is from the book "An Elementary Outline Of Mechanical Processes", by G. W. Danforth. Also available from Amazon: An elementary outline of mechanical processes.
The work of shaping iron into many forms by heating and hammering is a process which has been long in vogue, and it is far more widely known and practiced to-day than any of the other metal-shaping processes. Every village, and every farming and mining community has its blacksmith shop. The simple equipment needed for blacksmith work of the cruder sort makes this process readily available at any place where heat, hammer, and improvised anvil are at hand.
Blacksmithing is, strictly speaking, a re-manufacturing process, and it is practiced independent of other shops in turning out ready for use many products of forged iron with which everyone is familiar.
In a large building and repairing establishment the work of making forgings is divided between (1) the blacksmith shop, where forgings are made by manual labor on the anvil as in the village shop, and (2) the forge shop, where large forgings are made by the steam hammer.
The forgings made in the blacksmith shop are for the most part used just as the shop turns them out, or else they may require no other finishing than a little filing or grinding. Large forgings made under the steam hammer are almost always rough shapes to be machined accurately to required dimensions in the machine shop. Examples of this class of large forgings are crank and line shafts, cross-heads, connecting and piston rods, large braces and bolts, used in marine and stationary engines. Many parts of engines subject to stresses in motion are made of large forgings because of the greater homogeneity and reliability of their material as compared with cast steel.
The largest class of forgings, as large gun parts, shafts of large engines, etc., are special products in size and quality of material, and these are made, as was outlined in Chapter V (Mechanical Treatment Of Metals. Heat Treatment Of Metals. 142. Forms Of Newly Produced Metals), by the steel works which produce the special ingots necessary for them.
The process of drop-hammer forging has narrowed the field of work for the blacksmith shop, and not only has the drop hammer succeeded in making many forgings formerly made on the anvil by hand, but it makes many superior and complicated forged shapes heretofore made only as iron or steel castings or cut to shape at great expense in the machine shop.