FORGING

FORGING

Post 445

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Forging is a process of shaping iron and other malleable metals by hammering or pressing. Forging is carried out above or below the re-crystallization temperature of the metal. A primary purpose of forging is to shape a metal, but it also redefines the grain size and arrangements. The forged metal becomes more ductile. Forging improves the structure of a metal like better resistance to fatigue and impact, compared to other shaping processes such as casting or machining.

Forging with machine-hammer

Forging is mainly a shaping process where the metal is Drawn-out, Upset or Squeezed or compressed. Forging is also used to join metal pieces.

1 Drawing-out: The length is increased by decreasing the cross-section, such as wires, rolled sections, etc.

2 Upsetting: The length decreases but cross-section increases, such as for forming nails, rivets, bolts and coin stamping.

3 Bending: It is done by hammering the work around a form, such as for pipes, plates or dished ends (top-bottom of vessels).

4 Joining: Two pieces of metal form a joint, by hammering them together at high temperature (such as for copper and brass items).

5 Punching: Forming small openings or slits in the metal by a punch of the proper shape, often over a hollowed section. Punching is also accompanied by forming of the edge profiles.

6 Cutting Forming or cutting large holes or shapes by punching, shearing, etc.

Forging swagging tools

7 Die Forming: Forging is also squeezing metals by producing multi-directional flow to fill in a shaped die through compression. Shaping dies are, open, closed or impression dies. It is usually done hot to increase the plasticity of metal and so reduce the required force. Open-die forging is used to form parts that are too big for a closed die, or where only a few pieces are required. Closed-die forging is used for items to be made to close tolerances and where no machining is required. Coins are formed with impressions on two sides and also with side-edge patterns. Scooter and other carburetors are formed by pressure die casting, a process of forging.

Forging is also called a smithy. The chief activities of iron workshops, since ancient times, have been to heat the metal and beat it to a shape, or Forging. Hand-held Hammer has been chief tool for forging, but in the last two centuries powered hammers and presses are used.

Forged Aluminum wheels

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SMITHY

Post 396 – by Gautam Shah 

.power_hammer_at_a_smithy_in_finland

Smithy is a work-place where metals are worked by heating, casting, and hammering (forging) for quality modification, shaping and joining. Copper, bronze and silver were some of the first metals handled in workshops. Smithy is called a Forge. But bronze is not as malleable as copper or silver, and it was not readily forged or chased, but cast. Copper was shaped by forging. The traditions of metals like bronze and copper helped man to deal with cast iron –a castable metal, and little later wrought iron –a workable metal. The term to wrought derives from work.

typical smithy in Finland

A smithy is also called a forge, as hot shaping or forming is chief the activity here. The metal workshop processes are associated with hearth, a place to hammer, chisel, punch, shear bend a piece of iron, and water or oil for quenching the item.

Bassano_Forge_of_Vulcan

Metal pieces are heated to a temperature range at which work hardening does not happen. The heated metal piece is held with tongs and taken to the forge. Here the work-piece is held with tongs and other types of holders while forging. The heating and forging sequence is repeated several times, to maintain the temperature. The piece is than taken to a tub of water (or oil) for quenching or rapid cooling.

Iron Forge

Once upon a time forging workshops were independent units, owned by a smith and serving variety of needs of a neighbourhood. These needs were cooking vessels, plates, bowls, spikes, nails, cart axles, horse shoes, agricultural implements, tools, etc. Iron smiths were employed at construction sites to produce architectural entities such as lattices, screens, partitions, fences, stairs, balcony railings, horse appointments, weapons, posts, and building hardware, etc. ‘Locksmiths’ were fine crafts persons, with capacity to devise clocks, locks and other gadgets. Their ability was to rework a smithy item to finer details and embellish it with many different materials and techniques.

Blacksmith at work

Iron Smiths in later part of 18th C also began to work with rolled metal sheets, items such as trunks, cabinets, truck and other vehicles bodies, buckets, vessels, etc. These items of rolled metal sheets were cold-worked, and did not require any forging. Similarly Iron smiths began to be employed on construction work sites for cutting and rivetting rolled steel structural assemblies.

A smithy or forge has following tools and facilities. Some of these are now made from very superior materials and automated.

Hearth

A Hearth is a place where coal, charcoal or other fuels are burnt. It is designed to contain and control the fire by amount of air, volume of fuel, and shape of the flame or heat spread. The hearth is aided by a Tuyere (a pipe through which air is blown into fire) and Bellows or blower (for forcing air into the tuyere). Bellows were once made of leather, and blowers are fans moved manually or by power. The hearth fire is used for effecting metallurgical changes like hardening, annealing, and tempering, etc.

Working at Anvil

An anvil is a block on which forging is done. It is placed as very steady piece and used as a support for all metal manipulations. Its size and shape vary according to the weight of work piece and nature of operations. Most anvils have a wide base for stability, a body, a flatter main work face, projection called horn, and variety of edge forms, holes and depressions.

Tongs are used for holding, carrying and turning a hot metal piece. Tongs have similar mechanisms, that is long arms but variety of holder mouths. Vices are clamping devices mounted on work bench end.

Chisels are used for cutting and chipping, but separate for hot and cold work. Punches are like chisels but blunt edged for forming holes or depressions. A drift is a large sized wide cone punch used for enlarging punched holes.

Hammers for smithy

Hammers for smithy

Hammers are called a smith’s hand. Hammers have different weights of heads, types of head formations such as pean, eye, cheeks, face, and lengths of handles. A crafts person on own uses lighter to medium weight hammer as other hand is used for holding the iron piece in a tong, whereas an assistant uses both hand for a heavier sledge hammer. Nowadays power hammers are used.

Modern smithy have other facilities like lathes, drilling, shearing, punching machines, cutting saws, grinders and welding equipments.

This article on IRON SMITHY was published on my other Blog >>> http://talking-interior-design.blogspot.in/2014/11/iron-smithy-craft-1.html