WHAT IS FORGING?

Forging defined
At its most basic level, forging is the process of forming and shaping metals through the use of hammering, pressing or rolling. The process begins with starting stock, usually a rolling round steel , which is heated to its plastic deformation temperature, then upset or "kneaded" between dies to the desired shape and size.

During this hot forging process, the rolling steel, coarse grain structure is broken up and replaced by finer grains. Shrinkage and gas porosity inherent in the cast metal are consolidated through the reduction of the ingot, achieving sound centers and structural integrity. Mechanical properties are therefore improved through reduction of cast structure, voids and segregation. Forging also provides means for aligning the grain flow to best obtain desired directional strengths. Secondary processing, such as heat treating, can also be used to further refine the part.
Forging can create a myriad of sizes and shapes with enhanced properties when compared to castings or assemblies.

The forging industry continues to grow in technical prowess. OEMs are realizing that nothing beats forgings for strength and reliability. Advances in forging technology have expanded the range of shapes, sizes, and properties available in forged products to meet an increasing variety of design and performance requirements. Forgings are regularly specified where strength, reliability, economy, and resistance to shock and fatigue are vital considerations. Forged materials offer the desired degree of high or low temperature performance, ductility, hardness, and machinability.

In automotive and truck applications, forged components are commonly found at points of shock and stress. Cars and trucks may contain more than 250 forgings, most of which are produced from carbon or alloy steel. Forged engine and powertrain components include connecting rods, crankshafts, transmission shafts and gears, differential gears, drive shafts, clutch hubs, and universal joint yokes and crosses. Forged camshafts, pinions, gears, and rocker arms offer ease of selective hardening as well as strength. Wheel spindles, kingpins, axle beams and shafts, torsion bars, ball studs, idler arms, pitman arms, steering arms, and linkages for passenger cars, buses, and trucks typify applications requiring extra strength and toughness.

High strength-to-weight ratio and structural reliability improve performance, range, and payload capabilities of aircraft. That's why ferrous and nonferrous forgings are used in helicopters, piston-engine planes, commercial jets, and supersonic military aircraft. Many aircraft are "designed around" forgings, and contain more than 450 structural forgings as well as hundreds of forged engine parts. Forged parts include bulkheads, wing roots and spars, hinges, engine mounts, brackets, beams, shafts, bellcranks, landing-gear cylinders and struts, wheels, brake carriers and discs, and arresting hooks. In jet turbine engines, iron-based, nickel-base, and cobalt-base superalloys are forged into buckets, blades, couplings, discs, manifolds, rings, chambers, wheels, and shafts--all requiring uniformly high-yield tensile and creep rupture strengths, plus good ductility at temperatures ranging between 1,000 and 2,000°F. Forgings of stainless steels, maraging steels, titanium, and aluminum find similar applications at lower temperatures.
  

Strength, toughness, machinability, and economy account for the use of ferrous forgings in off-highway and heavy construction equipment, and in mining machinery. In addition to engine and transmission parts, forgings are used for gears, sprockets, levers, shafts, spindles, ball joints, wheel hubs, rollers, yokes, axle beams, bearing holders, and links. Farm implements, in addition to engine and transmission components, utilize key forgings ranging from gears, shafts, levers, and spindles to tie-rod ends, spike harrow teeth, and cultivator shanks.

Forged components are found in virtually every implement of defense, from rifle triggers to nuclear submarine drive shafts. Heavy tanks contain more than 550 separate forgings; The majority of 155-mm, 75-mm, and 3-in. shells as well as mortar projectiles contain at least two forged components.

For valves and fittings, the mechanical properties of forgings and their freedom from porosity are especially suited to high-pressure applications. Corrosion and heat-resistant materials are used for flanges, valve bodies and stems, tees, elbows, reducers, saddles, and other fittings. Oilfield applications include rock cutter bits, drilling hardware, and high-pressure valves and fittings.

Stationary and shipboard internal combustion engines include forged crankshafts, connecting rods, caps, camshafts, rocker arms, valves, gears, shafts, levers, and linkages. Outboard motors, motorcycles, and power saws offer examples of the intensive use of forgings in smaller engines. Industrial equipment industries use forgings in materials handling systems, conveyors, chain-hoist assemblies, and lift trucks.
 
"Forged" is the mark of quality in hand tools and hardware. Pliers, hammers, wrenches, and garden implements, as well as wire-rope clips and sockets, hooks, turnbuckles, and eye bolts are common examples. Strength, resistance to impact and fatigue, and excellent appearance are reasons why forgings have been the standard of quality since the earliest of times. The same is true of surgical instruments. Special hardware for electrical transmission and distribution lines is subject to high stresses and corrosion. For strength and dependability, forgings are used for parts such as pedestal caps, suspension clamps, sockets, and brackets.