Nasmyth’s Steam Hammer Revolutionized Steel Working
Commonly the hammer face itself carries the impression of the upper part of the article to be formed, i.e., there is an upper “die” on the hammer and a lower one on the anvil.
Modern Forging of an Automobile Crank Shaft
“Fins” were of course, left all around where the excess metal was squeezed out from between the upper and lower dies. It shortly developed that a second pair of dies shaped for trimming could clean the forging of this excess metal, which is so well known under the appellation, “flash.”
Nasmyth’s steam hammer, also, has been used very largely for drop-forging work.
A “cast” metal is not and cannot be as dense, free from holes, sponginess or other defects or as strong as “worked” metal. While often not as cheap as castings as far as cost of production goes, “drop forgings” are usually considerably superior to them and are to be preferred. However, it does not pay to make dies unless for many pieces. One or several “castings” can be made without great expense.
Forging of Large Pieces by Hydraulic Press
Of late years much forging has been done, not by the hammer which gives such a sudden, superficial blow with shallow working of the piece, but by hydraulic or other press, which very slowly squeezes the hot piece to smaller and longer shape. Sir Henry Bessemer was one of the first to realize the advantages of and make use of the press for steel working.