History of Metal Forming
The Art Of Forging is Already 6,000 Years Old
Before mankind started to use fire for its own purposes, it was a threat representing uncontrollable destruction. People tried to find an explanation for fire-spitting volcanoes and lightning strikes and attributed the natural phenomena to the wrath of the gods or the work of superior forces. It was not until fire was tamed for use that the cultural history basis for technical development was laid. Fire was initially a source of heat, protection against wild animals or a means for preparing food. People soon found out that metals like gold, silver, copper, lead and pewter could be shaped with fire. An important prerequisite for the evolution of the craft of forging – and for today's use of computer-calculated forging parts.
"Forging" is the generic term for all methods to form metal workpieces with heat and pressure. The forging of metals is one of the oldest working techniques of mankind. For millennia it has been an essential prerequisite for the introduction of improved cultivation methods, the development of crafts and trades, the production of devices and weapons and for shipbuilding.
Pure metals found in nature like gold, silver and copper were forged into jewellery, weapons and items for daily use around 4000 BC already. Rocks were used as hammers to shape the metal. Bronze, a copper and pewter alloy made with different additives, was known in Egypt, Mesopotamia and in the Mediterranean area after about 2500 BC. Even pieces of tin were produced for the processing into vessels. In the Mediterranean region, metal hammers with handles relieved rocks as forging tools in the 9th century BC already.
About 1000 BC, iron ranked as a precious metal and was used for ornamental items only. It gained in importance in the forging of weapons and tools between 700 and 500 BC and replaced the bronze used until then for the most part. Iron Celtic swords, daggers, shaving knives and brooches from the Hallstatt period (central European cultural period of the more ancient Iron Age) and the subsequent La-Tène period (central European cultural period of the more recent pre-Roman Iron Age) already document the use of different forging techniques. During everyday Roman life, forged iron played an important part in all areas of life. Romans reduced relatively pure ores in low hearths or even small shaft furnaces with charcoal using manual bellows and foot pumps. They then forged the clumps of iron gained this way.
The smelting and forging of iron with hammer and anvil were directly linked into the 13th and 14th century. Human muscle strength limited the size of forged parts well into the 14th century.
Water And Steam Replace Muscle Power
There was a leap forward in the development of forging technology made around 1500. Hammer mills were built along the courses of rivers. Attached to their water wheels with beech handles were iron hammer heads, the so-called tups, that were hitting on accordingly sized anvils. The machines powered by the flow energy of the water increased the muscle strength of humans many times over.
Next to individual aggregates in the form of heavy lift hammers, up to four hammers were coupled on a joint shaft in tilt hammer mills. With hammer tups with differing weight and increased hitting frequency, people were now able to produce crudely as well as finely forged goods. These water-powered hammer mills shaped forging technology into the 19th century.
By the end of the 18th century, the use of steam force in machines was spreading, helped along by James Watt among others. In the age of the industrial revolution after the mid-19th century, an energy source of a hitherto unknown dimension was available to forging technology. From that time on, the forging industry was independent of river locations and developed powerful steam hammers and later on air hammers. In steam hammers, the tup was connected to a piston inside a cylinder. Steam entering this cylinder raised tup and piston. The tup then hit the workpiece in a free fall. With the double-acting hammer, the force of the tup was increased with additional steam pressure during the downward motion onto the drive piston. The largest German steam hammer with a ram weight of 50 tons was the famous steam hammer Fritz that was used by the Krupp Company starting in 1861.
The Start of Drop Forging
The smiths of the late 19th and early 20th century used hammers driven by transmission shafts to produce a wide range of forged parts for the railways, for the car industry and for agricultural machinery.
From those days on forging made fast development into the highly automated and computerized forging methods of the present.