The Bushmaster XM-15 series (or XM15 ) is a line of AR-15 style semi-automatic rifles and carbines manufactured by Bushmaster Firearms International, LLC . Variants include the Bushmaster M4-type Carbine , Patrolman series, QRC series, Bushmaster XM15-E2S, and the Carbon 15 line.
101-467: The standard XM-15 has a forged 7075T6 aircraft-grade aluminum upper and lower receiver . Barrels of XM-15 firearms have a heavy profile and are hard chrome -lined 4150 alloy steel or 416 stainless steel . In Bushmaster's 2016 sales brochure, all new-production XM-15s are stated to be supplied with a 4150 steel barrel. The standard barrel has rifling of 1 turn in 9". The Bushmaster XM15-E2S "M4 type" carbine first gained notoriety for its use in
202-422: A component requires high strength ; such forgings usually require further processing (such as machining ) to achieve a finished part. Today, forging is a major worldwide industry. Forging is one of the oldest known metalworking processes. Traditionally, forging was performed by a smith using hammer and anvil , though introducing water power to the production and working of iron in the 12th century allowed
303-420: A distinctly different flow pattern. Both of these machines can be used for open-die or closed-die forging. A forging press , often just called a press, is used for press forging. There are two main types: mechanical and hydraulic presses. Mechanical presses function by using cams, cranks and/or toggles to produce a preset (a predetermined force at a certain location in the stroke) and reproducible stroke. Due to
404-588: A few disadvantages to this process, most stemming from the workpiece being in contact with the dies for such an extended period of time. The operation is a time-consuming process due to the amount and length of steps. The workpiece will cool faster because the dies are in contact with workpiece; the dies facilitate drastically more heat transfer than the surrounding atmosphere. As the workpiece cools it becomes stronger and less ductile, which may induce cracking if deformation continues. Therefore, heated dies are usually used to reduce heat loss, promote surface flow, and enable
505-508: A few. As a result of the Sandy Hook school shooting: Forging Forging is a manufacturing process involving the shaping of metal using localized compressive forces. The blows are delivered with a hammer (often a power hammer ) or a die . Forging is often classified according to the temperature at which it is performed: cold forging (a type of cold working ), warm forging, or hot forging (a type of hot working ). For
606-425: A hammer strikes and deforms the workpiece, which is placed on a stationary anvil . Open-die forging gets its name from the fact that the dies (the surfaces that are in contact with the workpiece) do not enclose the workpiece, allowing it to flow except where contacted by the dies. The operator therefore needs to orient and position the workpiece to get the desired shape. The dies are usually flat in shape, but some have
707-559: A mechanical press are its flexibility and greater capacity. The disadvantages include a slower, larger, and costlier machine to operate. The roll forging, upsetting, and automatic hot forging processes all use specialized machinery. Jewellery Jewellery (or jewelry in American English ) consists of decorative items worn for personal adornment such as brooches , rings , necklaces , earrings , pendants , bracelets , and cufflinks . Jewellery may be attached to
808-437: A more complex die design and the need for better lubrication and workpiece placement. There are other variations of part formation that integrate impression-die forging. One method incorporates casting a forging preform from liquid metal. The casting is removed after it has solidified, but while still hot. It is then finished in a single cavity die. The flash is trimmed, then the part is quench hardened. Another variation follows
909-572: A natural feel. However, any inclusion of lead or lead solder will give a British Assay office (the body which gives U.K. jewellery its stamp of approval, the Hallmark ) the right to destroy the piece, however, it is very rare for the assay office to do so. Beads are frequently used in jewellery. These may be made of glass, gemstones, metal, wood , shells, clay and polymer clay. Beaded jewellery commonly encompasses necklaces , bracelets , earrings , belts and rings . Beads may be large or small;
1010-437: A particular process window. To provide good forming conditions a homogeneous temperature distribution in the entire workpiece is necessary. Therefore, the control of the tool temperature has a major influence to the process. For example, by optimizing the preform geometries the local effective strains can be influenced to reduce local overheating for a more homogeneous temperature distribution. High-strength aluminium alloys have
1111-938: A responsible and modern alternative to mined diamonds. Retailers are responding to this trend by expanding their offerings of lab-grown diamond jewellery, further solidifying their place in the market. Many precious and semiprecious stones are used for jewellery. Among them are: Some gemstones (like pearls, coral, and amber) are classified as organic, meaning that they are produced by living organisms. Others are inorganic, meaning that they are generally composed of and arise from minerals. Some gems, for example, amethyst , have become less valued as methods of extracting and importing them have progressed. Some man-made gems can serve in place of natural gems, such as cubic zirconia , which can be used in place of diamonds. For platinum , gold , and silver jewellery, there are many techniques to create finishes. The most common are high-polish, satin/matte, brushed , and hammered. High-polished jewellery
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#17327761418521212-448: A ring can be classified: prong, bezel and tension setting. Synthetic diamonds, also referred to as lab-grown diamonds, are created using advanced technological processes such as High-Pressure High-Temperature (HPHT) and Chemical Vapor Deposition (CVD) . These methods result in diamonds that are chemically and physically identical to natural diamonds , offering the same brilliance and durability. The popularity of synthetic diamonds in
1313-602: A rounded steel hammer and hammering the jewellery to give it a wavy texture . Some jewellery is plated to give it a shiny, reflective look or to achieve a desired colour. Sterling silver jewellery may be plated with a thin layer of 0.999 fine silver (a process known as flashing) or plated with rhodium or gold. Base metal costume jewellery may also be plated with silver, gold, or rhodium for a more attractive finish. Jewellery has been used to denote status. In ancient Rome, only certain ranks could wear rings and later, sumptuary laws dictated who could wear what type of jewellery. This
1414-417: A specially shaped surface for specialized operations. For example, a die may have a round, concave, or convex surface or be a tool to form holes or be a cut-off tool. Open-die forgings can be worked into shapes which include discs, hubs, blocks, shafts (including step shafts or with flanges), sleeves, cylinders, flats, hexes, rounds, plate, and some custom shapes. Open-die forging lends itself to short runs and
1515-475: A status symbol, for its material properties, its patterns, or for meaningful symbols. Jewellery has been made to adorn nearly every body part, from hairpins to toe rings , and even genital jewellery . In modern European culture the amount worn by adult males is relatively low compared with other cultures and other periods in European culture. The word jewellery itself is derived from the word jewel , which
1616-573: A stone bracelet and marble ring are attributed to a similar age. Later, the European early modern humans had crude necklaces and bracelets of bone, teeth, berries, and stone hung on pieces of string or animal sinew , or pieces of carved bone used to secure clothing together. In some cases, jewellery had shell or mother-of-pearl pieces. A decorated engraved pendant (the Star Carr Pendant ) dating to around 11,000 BC, and thought to be
1717-759: A total of $ 73 million to families. XM-15 rifles were also used in the 1997 North Hollywood shootout , the 2018 Nashville Waffle House shooting , and the 2022 Buffalo shooting . An XM15-E2 was captured from Islamic State fighters in Sinjar Mountains by Peshmerga during the Iraqi Civil War . As of October 2, 2000, California has banned the Bushmaster XM15 by name in the Kasler v. Lockyer Assault Weapon List, among other AR-style rifles by Armalite , DPMS , Colt , and Eagle Arms , to name
1818-461: A two-to-one margin. In French and a few other European languages the equivalent term, joaillerie , may also cover decorated metalwork in precious metal such as objets d'art and church items, not just objects worn on the person. Humans have used jewellery for a number of different reasons: Most cultures at some point have had a practice of keeping large amounts of wealth stored in the form of jewellery. Numerous cultures store wedding dowries in
1919-556: A war zone and sold to finance an insurgency . The British crown jewels contain the Cullinan Diamond , part of the largest gem-quality rough diamond ever found (1905), at 3,106.75 carats (621.35 g). Now popular in engagement rings , this usage dates back to the marriage of Maximilian I to Mary of Burgundy in 1477. A popular style is the diamond solitaire, which features a single large diamond mounted prominently. Within solitaire, there are three categories in which
2020-400: A woman's death it was sold at the souk and recycled or sold to passers-by. Islamic jewellery from before the 19th century is thus exceedingly rare. The history of jewellery is long and goes back many years, with many different uses among different cultures. It has endured for thousands of years and has provided various insights into how ancient cultures worked. The earliest known Jewellery
2121-451: Is a forging process where a hammer is raised and then "dropped" into the workpiece to deform it according to the shape of the die. There are two types of drop forging: open-die drop forging and impression-die (or closed-die) drop forging. As the names imply, the difference is in the shape of the die, with the former not fully enclosing the workpiece, while the latter does. Open-die forging is also known as smith forging . In open-die forging,
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#17327761418522222-460: Is also very popular in many African and indigenous North American cultures. Silversmiths , goldsmiths , and lapidaries use methods including forging , casting , soldering or welding , cutting, carving and "cold-joining" (using adhesives , staples and rivets to assemble parts). Diamonds were first mined in India . Pliny may have mentioned them, although there is some debate as to
2323-412: Is appropriate for art smithing and custom work. In some cases, open-die forging may be employed to rough-shape ingots to prepare them for subsequent operations. Open-die forging may also orient the grain to increase strength in the required direction. " Cogging " is the successive deformation of a bar along its length using an open-die drop forge. It is commonly used to work a piece of raw material to
2424-401: Is deemed warm forging ; if below 30% of the recrystallization temperature (usually room temperature) then it is deemed cold forging . The main advantage of hot forging is that it can be done more quickly and precisely, and as the metal is deformed work hardening effects are negated by the recrystallization process. Cold forging typically results in work hardening of the piece. Drop forging
2525-456: Is forming of a work piece in a single step in several directions. The multidirectional forming takes place through constructive measures of the tool. The vertical movement of the press ram is redirected using wedges which distributes and redirects the force of the forging press in horizontal directions. Isothermal forging is a process by which the materials and the die are heated to the same temperature ( iso- meaning "equal"). Adiabatic heating
2626-427: Is its ability to deform the complete workpiece. Drop-hammer forging usually only deforms the surfaces of the work piece in contact with the hammer and anvil; the interior of the workpiece will stay relatively undeformed. Another advantage to the process includes the knowledge of the new part's strain rate. By controlling the compression rate of the press forging operation, the internal strain can be controlled. There are
2727-472: Is mainly used for aerospace applications. Magnesium alloys are more difficult to forge due to their low plasticity, low sensitivity to strain rates and narrow forming temperature. Using semi-open die hot forging with a three-slide forging press (TSFP) has become a newly developed forging method for Mg-Al alloy AZ31, commonly used in forming aircraft brackets. This forging method has shown to improve tensile properties but lacks uniform grain size. Even though
2828-448: Is most common when parts are forged without heating the slug, bar or billet. Aluminum is a common material that can be cold forged depending on final shape. Lubrication of the parts being formed is critical to increase the life of the mating dies. Unlike the above processes, induction forging is based on the type of heating style used. Many of the above processes can be used in conjunction with this heating method. Multidirectional forging
2929-447: Is nearly double that of conventional forging because contact times are on the order of 0.06-second. The downside is that this process is only feasible on smaller symmetric parts and cost; the initial investment can be over $ 10 million, so large quantities are required to justify this process. The process starts by heating the bar to 1,200 to 1,300 °C (2,190 to 2,370 °F) in less than 60 seconds using high-power induction coils. It
3030-460: Is one of the major reasons closed-die forgings are often used in the automotive and tool industries. Another reason forgings are common in these industrial sectors is that forgings generally have about a 20 percent higher strength-to-weight ratio compared to cast or machined parts of the same material. Forging dies are usually made of high-alloy or tool steel . Dies must be impact- and wear-resistant, maintain strength at high temperatures, and have
3131-415: Is reduced in thickness and increased in length. Roll forging is performed using two cylindrical or semi-cylindrical rolls, each containing one or more shaped grooves. A heated bar is inserted into the rolls and when it hits a spot the rolls rotate and the bar is progressively shaped as it is rolled through the machine. The piece is then transferred to the next set of grooves or turned around and reinserted into
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3232-454: Is required to operate the machinery. There is no flash produced so material savings are between 20 and 30% over conventional forging. The final product is a consistent 1,050 °C (1,920 °F) so air cooling will result in a part that is still easily machinable (the advantage being the lack of annealing required after forging). Tolerances are usually ±0.3 mm (0.012 in), surfaces are clean, and draft angles are 0.5 to 1°. Tool life
3333-660: Is the 'Gold Olive Wreath' (4th century BC), which is modeled on the type of wreath given as a prize for winners in athletic competitions like the Olympic Games. Jewellery dating from 600 to 475 BC is not well represented in the archaeological record, but after the Persian wars the quantity of jewellery again became more plentiful. One particularly popular type of design at this time was a bracelet decorated with snake and animal-heads Because these bracelets used considerably more metal, many examples were made from bronze. By 300 BC,
3434-419: Is the most common and gives the metal a highly reflective, shiny look. Satin, or matte finish reduces the shine and reflection of the jewellery, and this is commonly used to accentuate gemstones such as diamonds . Brushed finishes give the jewellery a textured look and are created by brushing a material (similar to sandpaper) against the metal, leaving "brush strokes". Hammered finishes are typically created using
3535-403: Is then descaled with rollers, sheared into blanks, and transferred through several successive forming stages, during which it is upset, preformed, final forged, and pierced (if necessary). This process can also be coupled with high-speed cold-forming operations. Generally, the cold forming operation will do the finishing stage so that the advantages of cold-working can be obtained, while maintaining
3636-407: Is used to assist in the deformation of the material, meaning the strain rates are highly controlled. This technique is commonly used for forging aluminium, which has a lower forging temperature than steels. Forging temperatures for aluminum are around 430 °C (806 °F), while steels and super alloys can be 930 to 1,260 °C (1,710 to 2,300 °F). Benefits: Disadvantages: Depending on
3737-423: Is usually sterling silver , or 92.5% fine silver. In costume jewellery , stainless steel findings are sometimes used. Other commonly used materials include glass , such as fused-glass or enamel ; wood , often carved or turned; shells and other natural animal substances such as bone and ivory ; natural clay ; polymer clay ; Hemp and other twines have been used as well to create jewellery that has more of
3838-677: The Royal Cemetery of Ur , where hundreds of burials dating 2900–2300 BC were unearthed; tombs such as that of Puabi contained a multitude of artefacts in gold, silver, and semi-precious stones, such as lapis lazuli crowns embellished with gold figurines, close-fitting collar necklaces, and jewel-headed pins. In Assyria , men and women both wore extensive amounts of jewellery, including amulets , ankle bracelets, heavy multi-strand necklaces, and cylinder seals . Jewellery in Mesopotamia tended to be manufactured from thin metal leaf and
3939-403: The die sooner than if there were no friction present, creating a much greater increase in the pressure required for the punch to finish the forging. The dimensional tolerances of a steel part produced using the impression-die forging method are outlined in the table below. The dimensions across the parting plane are affected by the closure of the dies, and are therefore dependent on die wear and
4040-617: The 26 victims of the shooting filed a class action lawsuit in Connecticut against Bushmaster, Remington Arms and others, seeking "unspecified" damages for the defendants ' purported negligent entrustment and illegal marketing of the XM-15 rifle. Plaintiffs argued that both theories of liability fell within exceptions to the 2005 Protection of Lawful Commerce in Arms Act , which affords broad civil immunity to gun manufacturers. The case
4141-724: The Berber cultures is a style of traditional jewellery worn by women and girls in the rural areas of the Maghreb region in North Africa inhabited by indigenous Berber people (in Berber language : Amazigh, Imazighen , pl). Following long social and cultural traditions, the silversmiths of different ethnic Berber groups of Morocco, Algeria and neighbouring countries created intricate jewellery to adorn their women and that formed part of their ethnic identity . Traditional Berber jewellery
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4242-457: The Gods. They worked two styles of pieces: cast pieces and pieces hammered out of sheet metal. Fewer pieces of cast jewellery have been recovered. It was made by casting the metal onto two stone or clay moulds. The two-halves were then joined, and wax , followed by molten metal, was placed in the centre. This technique had been practised since the late Bronze Age . The more common form of jewellery
4343-655: The Great conquered part of it. In earlier designs, other European influences can also be detected. When Roman rule came to Greece, no change in jewellery designs was detected. However, by 27 BC, Greek designs were heavily influenced by the Roman culture. That is not to say that indigenous design did not thrive. Numerous polychrome butterfly pendants on silver foxtail chains, dating from the 1st century, have been found near Olbia , with only one example ever found anywhere else. Gorgons, pomegranates, acorns, lotus flowers and palms were
4444-566: The Greeks had mastered making coloured jewellery and using amethysts , pearl , and emeralds . Also, the first signs of cameos appeared, with the Greeks creating them from Indian Sardonyx , a striped brown pink and cream agate stone. Greek jewellery was often simpler than in other cultures, with simple designs and workmanship. However, as time progressed, the designs grew in complexity and different materials were soon used. Jewellery in Greece
4545-521: The Kurgan settlement of Yunatsite near Pazardzhik , the golden treasure Sakar, as well as beads and gold jewellery found in the Kurgan settlement of Provadia – Solnitsata ("salt pit"). However, Varna gold is most often called the oldest since this treasure is the largest and most diverse. By approximately 5,000 years ago, jewellery-making had become a significant craft in the cities of Mesopotamia . The most significant archaeological evidence comes from
4646-580: The Museum of Ancient History in Lower Austria revealed that they had found a grave of a female jewellery worker – forcing archaeologists to take a fresh look at prehistoric gender roles after it appeared to be that of a female fine metal worker – a profession that was previously thought to have been carried out exclusively by men. The first signs of established jewellery making in Ancient Egypt
4747-614: The Mycenaean period, but unfortunately this skill was lost at the end of the Bronze Age. The forms and shapes of jewellery in ancient Greece such as the armring (13th century BC), brooch (10th century BC) and pins (7th century BC), have varied widely since the Bronze Age as well. Other forms of jewellery include wreaths, earrings, necklace and bracelets. A good example of the high quality that gold working techniques could achieve in Greece
4848-596: The October 2002 Beltway sniper attacks . A Bushmaster XM15-E2S carbine was displayed in a February 2011 video message by Caucasus Emirate leader, Dokka Umarov . Bushmaster rifles were captured by pro-Russian forces during the Russo-Georgian War . A Bushmaster XM-15 was used in the December 2012 Sandy Hook Elementary School shooting . Just before the two-year anniversary of the massacre, nine families of
4949-448: The U.S. featured a double-ring ceremony, up from 15% in the 1920s. Some religions have specific rules or traditions surrounding jewellery (or even prohibiting it) and many religions have edicts against excessive display. Islam, for instance, considers the wearing of gold by men as Haraam . The majority of Islamic jewellery was in the form of bridal dowries , and traditionally was not handed down from generation to generation; instead, on
5050-830: The Western practice of married people wearing wedding rings). Wearing of amulets and devotional medals to provide protection or to ward off evil is common in some cultures. These may take the form of symbols (such as the ankh ), stones, plants, animals, body parts (such as the Khamsa ), or glyphs (such as stylised versions of the Throne Verse in Islamic art ). In creating jewellery, gemstones , coins , or other precious items are often used, and they are typically set into precious metals . Platinum alloys range from 900 (90% pure) to 950 (95% pure). The silver used in jewellery
5151-408: The ability to withstand cycles of rapid heating and cooling. In order to produce a better, more economical die the following standards are maintained: Barrelling occurs when, due to friction between the work piece and the die or punch , the work piece bulges at its centre in such a way as to resemble a barrel . This leads to the central part of the work piece to come in contact with the sides of
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#17327761418525252-488: The application of magnesium alloys increases by 15–20% each year in the aerospace and automotive industry, forging magnesium alloys with specialized dies is expensive and an unfeasible method to produce parts for a mass market. Instead, most magnesium alloy parts for industry are produced by casting methods. The most common type of forging equipment is the hammer and anvil. Principles behind the hammer and anvil are still used today in drop-hammer equipment. The principle behind
5353-469: The body or the clothes. From a western perspective, the term is restricted to durable ornaments , excluding flowers for example. For many centuries metal such as gold often combined with gemstones , has been the normal material for jewellery, but other materials such as glass, shells and other plant materials may be used. Jewellery is one of the oldest types of archaeological artefact – with 100,000-year-old beads made from Nassarius shells thought to be
5454-475: The dies, allowing for easy automation. Upset forging increases the diameter of the workpiece by compressing its length. Based on number of pieces produced, this is the most widely used forging process. A few examples of common parts produced using the upset forging process are engine valves, couplings, bolts, screws, and other fasteners. Upset forging is usually done in special high-speed machines called crank presses . The machines are usually set up to work in
5555-434: The dies. Press forging works by slowly applying a continuous pressure or force, which differs from the near-instantaneous impact of drop-hammer forging. The amount of time the dies are in contact with the workpiece is measured in seconds (as compared to the milliseconds of drop-hammer forges). The press forging operation can be done either cold or hot. The main advantage of press forging, as compared to drop-hammer forging,
5656-458: The direct heat treatment of parts after forging. One variation of impression-die forging is called "flashless forging", or "true closed-die forging". In this type of forging, the die cavities are completely closed, which keeps the workpiece from forming flash. The major advantage to this process is that less metal is lost to flash. Flash can account for 20 to 45% of the starting material. The disadvantages of this process include additional cost due to
5757-470: The exact nature of the stone he referred to as Adamas . In 2005, Australia , Botswana , Russia and Canada ranked among the primary sources of gemstone diamond production. There are negative consequences of the diamond trade in certain areas. Diamonds mined during the recent civil wars in Angola , Ivory Coast , Sierra Leone , and other nations have been labeled as blood diamonds when they are mined in
5858-445: The final product from a precision forging needs little or no final machining. Cost savings are gained from the use of less material, and thus less scrap, the overall decrease in energy used, and the reduction or elimination of machining. Precision forging also requires less of a draft, 1° to 0°. The downside of this process is its cost, therefore it is only implemented if significant cost reduction can be achieved. Near net shape forging
5959-620: The five fingers of the hand and is traditionally believed both by Muslims as well as Jewish people to protect against the evil eye . The oldest gold jewellery in the world is dating from 4,600 BC to 4,200 BC and was discovered in Europe, at the site of Varna Necropolis , near the Black Sea coast in Bulgaria . Several prehistoric Bulgarian finds are considered no less old – the golden treasures of Hotnitsa, Durankulak , artifacts from
6060-450: The following forging processes can be performed at various temperatures; however, they are generally classified by whether the metal temperature is above or below the recrystallization temperature. If the temperature is above the material's recrystallization temperature it is deemed hot forging ; if the temperature is below the material's recrystallization temperature but above 30% of the recrystallization temperature (on an absolute scale) it
6161-439: The form of jewellery or make jewellery as a means to store or display coins. Alternatively, jewellery has been used as a currency or trade good to buy and sell. an example being the use of slave beads . Many items of jewellery, such as brooches and buckles , originated as purely functional items, but evolved into decorative items as their functional requirement diminished. Similarly, Tiffany & Co . produced inkwells in
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#17327761418526262-402: The forming temperature steel forging can be divided into: For industrial processes steel alloys are primarily forged in hot condition. Brass, bronze, copper, precious metals and their alloys are manufactured by cold forging processes; each metal requires a different forging temperature. Due to the narrow temperature range and high thermal conductivity, aluminium forging can only be realized in
6363-456: The foundation. Moreover, a large machine base is needed to absorb the impacts. To overcome some shortcomings of the drop-hammer, the counterblow machine or impactor is used. In a counterblow machine both the hammer and anvil move and the workpiece is held between them. Here excess energy becomes recoil. This allows the machine to work horizontally and have a smaller base. Other advantages include less noise, heat and vibration. It also produces
6464-415: The high speed of automatic hot forging. Examples of parts made by this process are: wheel hub unit bearings, transmission gears, tapered roller bearing races, stainless steel coupling flanges, and neck rings for liquid propane (LP) gas cylinders. Manual transmission gears are an example of automatic hot forging used in conjunction with cold working. Roll forging is a process where round or flat bar stock
6565-446: The horizontal plane, to facilitate the quick exchange of workpieces from one station to the next, but upsetting can also be done in a vertical crank press or a hydraulic press. The initial workpiece is usually wire or rod, but some machines can accept bars up to 25 cm (9.8 in) in diameter and a capacity of over 1000 tons. The standard upsetting machine employs split dies that contain multiple cavities. The dies open enough to allow
6666-614: The jewellery had significance. Green, for example, symbolised fertility. Lapis lazuli and silver had to be imported from beyond the country's borders. Egyptian designs were most common in Phoenician jewellery. Also, ancient Turkish designs found in Persian jewellery suggest that trade between the Middle East and Europe was not uncommon. Women wore elaborate gold and silver pieces that were used in ceremonies. Jewellery of
6767-465: The jewellery market has increased significantly due to several factors. Their typically lower price compared to natural diamonds makes them an appealing choice for many consumers. Additionally, the ethical implications of synthetic diamonds have garnered attention, particularly their potential to eliminate the risks associated with conflict diamonds , which are mined in war zones and often used to finance armed conflict. From an environmental perspective,
6868-530: The late 19th and early 20th centuries, skillfully combining materials like enamel and fine metals, reflecting the same craftsmanship seen in their jewellery collections. These inkwells were not only practical but also artistic in design. Jewellery can symbolise group membership (as in the case, of the Christian crucifix or the Jewish Star of David ) or status (as in the case of chains of office , or
6969-492: The latter two, the metal is heated , usually in a forge . Forged parts can range in weight from less than a kilogram to hundreds of metric tons. Forging has been done by smiths for millennia; the traditional products were kitchenware , hardware , hand tools , edged weapons , cymbals , and jewellery . Since the Industrial Revolution , forged parts are widely used in mechanisms and machines wherever
7070-465: The machine at room temperature and hot forged products emerge from the other end. This all occurs rapidly; small parts can be made at a rate of 180 parts per minute (ppm) and larger can be made at a rate of 90 ppm. The parts can be solid or hollow, round or symmetrical, up to 6 kg (13 lb), and up to 18 cm (7.1 in) in diameter. The main advantages to this process are its high output rate and ability to accept low-cost materials. Little labor
7171-444: The machine is simple: raise the hammer and drop it or propel it into the workpiece, which rests on the anvil. The main variations between drop-hammers are in the way the hammer is powered; the most common being air and steam hammers. Drop-hammers usually operate in a vertical position. The main reason for this is excess energy (energy that is not used to deform the workpiece) that is not released as heat or sound needs to be transmitted to
7272-493: The metal to completely fill the die cavity. After forging, the flash is removed. In commercial impression-die forging, the workpiece is usually moved through a series of cavities in a die to get from an ingot to the final form. The first impression is used to distribute the metal into the rough shape in accordance to the needs of later cavities; this impression is called an "edging", "fullering", or "bending" impression. The following cavities are called "blocking" cavities, in which
7373-407: The nature of this type of system, different forces are available at different stroke positions. Mechanical presses are faster than their hydraulic counterparts (up to 50 strokes per minute). Their capacities range from 3 to 160 MN (300 to 18,000 short tons-force). Hydraulic presses, such as the four-die device , use fluid pressure and a piston to generate force. The advantages of a hydraulic press over
7474-522: The oldest Mesolithic art in Britain, was found at the site of Star Carr in North Yorkshire in 2015. In southern Russia , carved bracelets made of mammoth tusk have been found. The Venus of Hohle Fels features a perforation at the top, showing that it was intended to be worn as a pendant . Around seven thousand years ago, the first sign of copper jewellery was seen. In October 2012,
7575-602: The oldest known jewellery. The basic forms of jewellery vary between cultures but are often extremely long-lived; in European cultures the most common forms of jewellery listed above have persisted since ancient times, while other forms such as adornments for the nose or ankle, important in other cultures, are much less common. Jewellery may be made from a wide range of materials. Gemstones and similar materials such as amber and coral , precious metals , beads , and shells have been widely used, and enamel has often been important. In most cultures jewellery can be understood as
7676-630: The operation can be used to create any size part because there is no limit to the size of the press forging machine. New press forging techniques have been able to create a higher degree of mechanical and orientation integrity. By the constraint of oxidation to the outer layers of the part, reduced levels of microcracking occur in the finished part. Press forging can be used to perform all types of forging, including open-die and impression-die forging. Impression-die press forging usually requires less draft than drop forging and has better dimensional accuracy. Also, press forgings can often be done in one closing of
7777-579: The piece is working into a shape that more closely resembles the final product. These stages usually impart the workpiece with generous bends and large fillets . The final shape is forged in a "final" or "finisher" impression cavity. If there is only a short run of parts to be done, then it may be more economical for the die to lack a final impression cavity and instead machine the final features. Impression-die forging has been improved in recent years through increased automation which includes induction heating, mechanical feeding, positioning and manipulation, and
7878-405: The production of finer details and closer tolerances. The workpiece may also need to be reheated. When done in high productivity, press forging is more economical than hammer forging. The operation also creates closer tolerances. In hammer forging a lot of the work is absorbed by the machinery; when in press forging, the greater percentage of work is used in the work piece. Another advantage is that
7979-505: The production of synthetic diamonds generally has a smaller ecological footprint than traditional diamond mining , which can result in extensive land degradation and habitat destruction. While lab-grown diamonds do require energy for their production, many companies are actively adopting renewable energy sources to mitigate their environmental impact. As consumer preferences evolve, particularly among younger generations who prioritize sustainability, synthetic diamonds are increasingly seen as
8080-414: The proper thickness. Once the proper thickness is achieved the proper width is achieved via "edging". " Edging " is the process of concentrating material using a concave shaped open-die. The process is called "edging" because it is usually carried out on the ends of the workpiece. " Fullering " is a similar process that thins out sections of the forging using a convex shaped die. These processes prepare
8181-444: The same grooves. This continues until the desired shape and size is achieved. The advantage of this process is there is no flash and it imparts a favorable grain structure into the workpiece. Examples of products produced using this method include axles , tapered levers and leaf springs . This process is also known as precision forging . It was developed to minimize cost and waste associated with post-forging operations. Therefore,
8282-475: The same process as outlined above, except the preform is produced by the spraying deposition of metal droplets into shaped collectors (similar to the Osprey process ). Closed-die forging has a high initial cost due to the creation of dies and required design work to make working die cavities. However, it has low recurring costs for each part, thus forgings become more economical with greater production volume. This
8383-407: The scale of milliseconds. Depending on the size and complexity of the part, the hammer may be dropped multiple times in quick succession. Excess metal is squeezed out of the die cavities, forming what is referred to as " flash ". The flash cools more rapidly than the rest of the material; this cool metal is stronger than the metal in the die, so it helps prevent more flash from forming. This also forces
8484-417: The slang term bling-bling , which refers to the ostentatious display of jewellery by men or women. Conversely, the jewellery industry in the early 20th century launched a campaign to popularise wedding rings for men, which caught on, as well as engagement rings for men, which did not, go so far as to create a false history and claim that the practice had medieval roots. By the mid-1940s, 85% of weddings in
8585-482: The smallest type of beads used are known as seed beads , these are the beads used for the "woven" style of beaded jewellery. Seed beads are also used in an embroidery technique where they are sewn onto fabric backings to create broad collar neck pieces and beaded bracelets. Bead embroidery, a popular type of handwork during the Victorian era , is enjoying a renaissance in modern jewellery making. Beading, or beadwork,
8686-616: The tensile strength of medium strong steel alloys while providing significant weight advantages. Therefore, aluminium forged parts are mainly used in aerospace, automotive industry and many other fields of engineering especially in those fields, where highest safety standards against failure by abuse, by shock or vibratory stresses are needed. Such parts are for example pistons, chassis parts, steering components and brake parts. Commonly used alloys are AlSi1MgMn ( EN AW-6082 ) and AlZnMgCu1,5 ( EN AW-7075 ). About 80% of all aluminium forged parts are made of AlSi1MgMn. The high-strength alloy AlZnMgCu1,5
8787-422: The thickness of the final flash. Dimensions that are completely contained within a single die segment or half can be maintained at a significantly greater level of accuracy. A lubricant is used when forging to reduce friction and wear. It is also used as a thermal barrier to restrict heat transfer from the workpiece to the die. Finally, the lubricant acts as a parting compound to prevent the part from sticking in
8888-622: The thousands of pounds. Smaller power hammers , 500 lb (230 kg) or less reciprocating weight, and hydraulic presses are common in art smithies as well. Some steam hammers remain in use, but they became obsolete with the availability of the other, more convenient, power sources. There are many different kinds of forging processes available; however, they can be grouped into three main classes: Common forging processes include: roll forging, swaging , cogging , open-die forging, impression-die forging (closed die forging), press forging, cold forging, automatic hot forging and upsetting. All of
8989-584: The trade and manufacture of jewellery have also been unearthed throughout Mesopotamian archaeological sites. One record in the Mari royal archives, for example, gives the composition of various items of jewellery: The Greeks started using gold and gems in jewellery in 1600 BC, although beads shaped as shells and animals were produced widely in earlier times. Around 1500 BC, the main techniques of working gold in Greece included casting, twisting bars, and making wire. Many of these sophisticated techniques were popular in
9090-514: The use of large trip hammers or power hammers that increased the amount and size of iron that could be produced and forged. The smithy or forge has evolved over centuries to become a facility with engineered processes, production equipment, tooling, raw materials and products to meet the demands of modern industry. In modern times, industrial forging is done either with presses or with hammers powered by compressed air, electricity, hydraulics or steam. These hammers may have reciprocating weights in
9191-545: The workpiece to move from one cavity to the next; the dies then close and the heading tool, or ram, then moves longitudinally against the bar, upsetting it into the cavity. If all of the cavities are utilized on every cycle, then a finished part will be produced with every cycle, which makes this process advantageous for mass production. These rules must be followed when designing parts to be upset forged: The automatic hot forging process involves feeding mill-length steel bars (typically 7 m (23 ft) long) into one end of
9292-412: The workpieces for further forging processes. Impression-die forging is also called "closed-die forging". In impression-die forging, the metal is placed in a die resembling a mold, which is attached to an anvil. Usually, the hammer die is shaped as well. The hammer is then dropped on the workpiece, causing the metal to flow and fill the die cavities. The hammer is generally in contact with the workpiece on
9393-590: Was anglicised from the Old French " jouel ", and beyond that, to the Latin word " jocale ", meaning plaything. In British English , Indian English , New Zealand English , Hiberno-English , Australian English , and South African English it is spelled jewellery. At the same time, the spelling is jewelry in American English . Both are used in Canadian English . However, jewellery prevails by
9494-518: Was actually created not by modern humans ( Homo sapiens ) but by Neanderthal living in Europe. Specifically, perforated beads made from small seashells have been found dating to 115,000 years ago in the Cueva de los Aviones, a cave along the southeast coast of Spain. Later in Kenya, at Enkapune Ya Muto , beads made from perforated ostrich eggshells have been dated to more than 40,000 years ago. In Russia,
9595-465: Was also based on the rank of the citizens of that time. Cultural dictates have also played a significant role. For example, the wearing of earrings by Western men was considered effeminate in the 19th century and early 20th century. More recently, the display of body jewellery, such as piercings , has become a mark of acceptance or seen as a badge of courage within some groups but is completely rejected in others. Likewise, hip hop culture has popularised
9696-484: Was around 3,000–5,000 years ago. The Egyptians preferred the luxury, rarity, and workability of gold over other metals. In Predynastic Egypt jewellery soon began to symbolise political and religious power in the community. Although it was worn by wealthy Egyptians in life, it was also worn by them in death, with jewellery commonly placed among grave goods . In conjunction with gold jewellery, Egyptians used coloured glass , along with semi-precious gems. The colour of
9797-708: Was dismissed in superior court and was appealed to the Connecticut Supreme Court . In March 2019, the Connecticut Supreme Court reinstated the wrongful death lawsuit, holding that the plaintiffs successfully pleaded a cause of action for illegal marketing. Remington appealed to the United States Supreme Court, which denied review on November 12, 2019. On February 15, 2022, Remington Arms insurers settled with families of Sandy Hook victims and agreed to pay
9898-441: Was hardly worn and was mostly used for public appearances or on special occasions. It was frequently given as a gift and was predominantly worn by women to show their wealth, social status, and beauty. The jewellery was often supposed to give the wearer protection from the " evil eye " or endowed the owner with supernatural powers , while others had a religious symbolism. Older pieces of jewellery that have been found were dedicated to
9999-457: Was set with large numbers of brightly coloured stones (chiefly agate, lapis, carnelian, and jasper). Favoured shapes included leaves, spirals, cones, and bunches of grapes. Jewellers created works both for human use and for adorning statues and idols. They employed a wide variety of sophisticated metalworking techniques, such as cloisonné , engraving , fine granulation , and filigree . Extensive and meticulously maintained records pertaining to
10100-491: Was the hammered sheet type. Sheets of metal would be hammered to thickness and then soldered together. The inside of the two sheets would be filled with wax or another liquid to preserve the metal work. Different techniques, such as using a stamp or engraving, were then used to create motifs on the jewellery. Jewels may then be added to hollows or glass poured into special cavities on the surface. The Greeks took much of their designs from outer origins, such as Asia, when Alexander
10201-465: Was usually made of silver and includes elaborate brooches made of triangular plates and pins ( fibula ), originally used as clasps for garments, but also necklaces, bracelets, earrings and similar items. Another major type is the so-called khmissa (local pronunciation of the Arabic word "khamsa" for the number "five"), which is called afus in the Berber language ( Tamazight) . This form represents
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