Human beings have likely utilized forging as a metal fabrication process for thousands of years. Although forging methods changed over the course of time, the process remains immensely popular today.
During previous centuries, a blacksmith forged metal components by using a hammer to strike heated metal arrayed on the surface of an anvil. During the 12th century, some manufacturers began experimenting with the use of water-powered wheels to increase the size and power of hammers employed during the forging process. This innovation permitted the production of forged metals in larger sizes.
Today, modern forges have evolved into sophisticated metal fabrication plants. Most of these facilities possess an array of production equipment, tools and tooling machines, and inventories. Presses and automated hammering machinery have largely replace grueling physical labor in powering the modern smithy.
In-demand forged metal parts serve many economic sectors during the current era. Consider just a few of the vital industries which depend upon these components: construction and building trades, heavy industry and manufacturing, aerospace and aviation, gas and energy, the automotive industry, telecommunications, maritime industries, the electronics and high tech industries, and more!
During metal forging, a manufacturer reforms a metal part into different dimensions via the application of thermal and mechanical energy. For example, this process will transform a steel billot or ingot into a new shape. The path from raw material to a forged part typically involves several steps:
A manufacturer usually attempts to develop the general shape of the forged part at an early stage in the forging process. By cutting pieces off an extrusion into a workable form, the manufacturer distinguishes the general size of the final part, for instance. This step frequently involves mechanically separating billets of a desired size from round, square or uniquely shaped bars.
The application of heat helps create a more malleable surface. Manufacturers may heat metal alloys undergoing forging within the designated temperature ranges specified for each alloy. For instance, forging pure copper requires less heat than forging pure nickel because copper maintains a lower melting point than nickel.
Just as a blacksmith long ago might place a hot chunk of iron onto an anvil to hammer out a horseshoe, manufacturers today position heated metal precisely in order to conduct forging. Most modern facilities automatically handle this step, ensuring that heated metal crosses along an assembly line to a specific location (the lower die) for further fabrication. Facilities lacking this level of automation would need to position the hot metal into the correct configuration in order to perform forging. For instance, a worker wearing heavily padded gloves and other protective gear might transfer small pieces of hot metal from a heated bucket onto a die serving as an anvil with the assistance of very long tongs and/or an overhead hoist.
Next, the manufacturer impacts the shape of the metal part through the application of intense force. Like an old-fashioned smithy wielding a heavy tool, the metal fabricators of today apply mechanical pressure via a moving forging die to compress and manipulate the shape of hot metal parts located on a lower forging die. The manufacturer uses a heavy press or other mechanical means to strike the upper forging die against the hot metal.
Most modern metal fabrication facilities automate the process of forging today. Metal parts may proceed through an assembly line, encountering multiple lower and upper forging dies during the course of manufacturing. Impressions on the dies modify the appearance of the metal part at each stage.
When contact occurs between two closing upper and lower dies, the pressure forces molten metal from extremely hot billets into a rim or “gutter” area where the dies make contact with one another. The metal in this region forms a plug as the dies close and squeeze out displaced material. The excess frequently forms a ridge or a series of metal burrs on the part called “flash”. Manufacturers must later trim away this excess metal in order to obtain the desired part shape.
A process known as “true closed die” or “flashless” forging eliminates the cavities in the die, so flash does not form; taking this step may reduce the cost of part production in high volume production runs because manufacturers do not need to expend resources trimming away the flash from the metal part during finishing. However, trued closed die forging may increase costs associated with designing the dies and positioning hot metal correctly on the assembly line.
After the removal of flash, manufacturers typically conduct any further required finishing on a metal part. This process may involve first acid treating or shot blasting the part to provide a better texture for the application of a surface finish. Frequently, manufacturers will conduct machining operations on forged parts. They may subject the part to milling, turning, drilling or other physical modifications to achieve a desired form.
Manufacturers currently conduct forging using a variety of metals and metal alloys. Some of the most common operations include:
Forged aluminum products offer the advantages of strength and light weight. Manufacturers may use forging to create parts designed to function in locations in which shocks or impacts might occur, for instance. For this reason, wheel spindles, gears and engine pistons often depend upon forged components.
Copper and its alloys provide excellent raw materials for the forging process. These materials typically undergo commercial forging without requiring any re-strikes. The malleability of copper may allow the use of a single die press and permit a rate of 200 to 600 forged pieces completed per hour in automated environments.
Magnesium also forges readily. The metal tolerates extensive machining after forging.
Nonmagnetic stainless steel usually requires a higher forging temperature than magnetic stainless steel. Modern manufacturers perform a wide array of forgings using stainless steel, since these alloys play an important part in numerous industries.
The strength of forged steel contributes to the popularity of this product. Numerous steel industrial parts undergo open die forging, for example.
Some important differences exist between the process of casting and forging. These difference contribute to structural differences in a metal part:
During casting, a manufacturer typically heats metal into a liquid form and then pours the molten material into a mold to cool. As it hardens, the metal will recrystallize in a new shape. Bubbles of gases may become trapped within the cooling liquid and small surface irregularities may occur where gases escaped. By contrast, during forging, the manufacturer applies thermal energy and pressure to alter the shape of an existing metal part. The forging process typically compresses and compacts the metal and causes grain flow changes in conformity with the shape of the part.
Depending upon the manufacturing environment, the forging process today generally produce stronger, more reliable and more impact-resistant metal parts than the casting process. Forged parts may display superior tensile strength, fatigue strength and yield strength. A forged part typically must endure greater deformation before failing than a cast part.
Forging helps reduce problems caused by porosity, which may occur during the casting process as bubbles of gas become trapped inside molten metal. By compressing hot metal, forging permits the removal of these defects (which sometimes weaken cast metal parts). Thus, well-forged parts usually demonstrate better strength and impact resistance. Depending upon the manufacturing environment and the degree of automation, forging often proves more cost-effective and permits closer tolerances than casting. This process represents a flexible, popular alternative for metal fabrication.
The process of metal forging offers a number of advantages for manufacturers. Whether you seek forged metals in high volumes or smaller quantities, you’ll obtain a number of benefits.
Compared with castings, extrusions or machined bar stock, forging sometimes furnishes a cost-effective alternative. This process reduces the time required to generate a metal part.
Additionally, forging typically provides an opportunity for the manufacturer to improve the strength of the metal component. Whether forging stainless steel or relying upon aluminum forgings, a manufacturer by using this process may enhance leak resistance in some items. It may help strengthen thin metal surfaces in some products, reducing leaking potential.
Ultimately, forging enables some manufacturers to supply metal parts engineered within close tolerances. Companies maintaining rigorous quality controls standards attest to the benefits of this process. A grain flow comparison of the interior of the metal before and after forging may prove illuminating also!
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