Laval University

From the SelectedWorks of Fathi Habashi

August, 2007

History of Metal Casting Fathi Habashi

Available at: https://works.bepress.com/fathi_habashi/438/

History of Metal Casting

Fathi Habashi Department of Mining, Metallurgical, and Materials Engineering Laval University, Quebec City, Canada [email protected]

metallurgy

History of Metal Casting—Part 1 by Fathi Habashi, Department of Mining, Metallurgical, and Materials Engineering, Laval University

believe that my work would surely be almost a seed without fruit and that I would fail in that cause which disposed me to satisfy your request I to write and form this work if, while labouring on it, 1 did not tell you of the art of casting, since it is a necessary means to very many ends. It is especially necessary since this art and work is not well known, so that no one can practice it who is not, so to speak, born to it, or who does not have much talent and good judgment. For this reason and also because it is closely related to sculpture, whose arms are the support of its life, it is very highly esteemed… it is a profitable and skilful art and in large part delightful. [BIRINGUCCIO, IN PIROTECHNIA, 1540]

Introduction

The history of metal casting is the history of metal- lurgy. Metals produced in a furnace are melted and cast to form useful objects, whether a piece of jewelry, an agri- cultural tool, or a weapon. Objects made of gold, silver, copper, bronze, brass, tin, lead, and iron conserved in museums are a testimony to the cleverness of the ancient metal workers. The history of casting is also the history of art since most castings are made by artists. Ancient Egyptian wall paintings give an excellent illustration of the melting and casting of gold and copper. Most of the important Egyptian castings were used for making jew- elry and masks. Copper was traded in the form of large cast ingots.

The Colossus of Rhodes is an immense bronze statue Ancient Egyptian wall painting illustrating the casting of copper of Apollo the Sun God and protecting deity of Rhodes, constructed during the period from 292 to 280 BC, which stood at the entrance to Rhodes Harbour. It fell to pieces in 224 BC when an earthquake struck the island. It remained there for centuries until the Arabs gained possession of the island in 672 AD and sold what remained as scrap metal. The description of the statue is known only through writings of the Roman historian Pliny who visited the island in the first century AD. The statue stood about 32 metres high and weighed 300 tonnes. The Etruscans and Romans also cast large bronze statutes.

In ancient China, massive bronze vessels were cast dur- ing the Han Dynasty (206 BC to 220 AD). The brilliant age of Japanese bronze founding dates back to the introduction Large statue of the Roman emperor of Buddhism, in the sixth century AD in Nara, the ancient Ancient copper ingot Marcus Aurelius in Rome capital of Japan. Among the Japanese creations of this period was the colossal 380-tonne seated Buddha of Todaiji, consort of Shiva, is the nourishing and life-giving bronze gilded with 440 kilograms of gold. In India, Parvati, the statue dating back to about 950 AD.

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The same technique used for casting large bells in ancient China was later used in It was the church that provided Europe to cast cannons when gun powder the greatest outlet for their skills in bell founding became known around 1250 AD. The fall of to supply bells for the cathedrals and abbeys. Constantinople in 1453 was a turning point in the history of the world; city walls were bombarded by stone balls thrown by huge cannons con- Columbian Mexico, and the Benin civilization in Africa structed by the Turks. During medieval times in Europe, the used this method of casting to produce their artwork in foundry men and smiths produced weapons and armour, copper, bronze, and gold. household utensils and tools, swords, and other imple- ments demanded by the feudal lords. However, it was the In this method, the smith church that provided the greatest outlet for their skills in creates a pattern for the cast- bell founding to supply bells for the cathedrals and abbeys. ing by covering one of the Because of its size and importance, bell founding raised the cores with beeswax and care- casting of metal to the class of a practical art. At the time of fully modelling it into the war, bells were often melted down and made into weapons. desired shape. When the wax form is finished to the artist’s Some medieval technical manuals, such as De Diversibus satisfaction, it is covered in a Artibus (On the Different Arts), the earliest known foundry thick coating of clay. The text, written around 1120 by the German Benedictine monk cores are made to be self sup- Theophilus Presbyter (circa 1070-1125), give detailed porting. This mould is accounts of the tools and equipment used for the gold- allowed to air dry. When a smiths’ work. The invention of movable and cast lead type batch of moulds has been cre- Bronze statue of Parvati, the consort for the printing press in 1450 was an important application ated and is ready for casting, it of Shiva, dating from about 950 AD— of casting. is placed in a fire and heated an example of Indian artistic casting so that the wax melts. The The casting of bells and wax is collected through a runner and can be reused after cannons was described at any foreign matter is removed. The clay moulds are further length by Vannoccio heated to a point where they are sufficiently hard. This per- Biringuccio (1480-1539), mits the pouring of the molten metal without causing the the head of the Papal shell to burst. The moulds are then placed upright on the Foundry in Rome, in his floor and molten brass is poured into the open mould. Soon Pirotechnia, published in after casting, the molds are broken open, the shell knocked 1540, one year after his off, and the final object is cleaned, filed, and polished. death. While at the Paris Coating the wax pattern with layers of clay became known Arsenal, Pierre Surirey de as investment. Saint Remy (1645-1716) wrote a two-volume book Shortly after the Dark Ages in Europe, the industrious The colossal 380-tonne seated Buddha in in 1697 entitled Memoires sculptor and goldsmith Benvenuto Cellini (1500–1571) Todaiji, Japan, gilded with 440 kilograms of gold d’artillerie, which con- began to make use of the lost wax tained valuable informa- method of casting, which he learned tion on casting cannons. The close ties between casting and from the writings of the monk pottery indicate that the two arts must have developed simul- Theophilus. In his autobiography, taneously. It was the potter’s art—the selection and com- Cellini described in detail the casting of pounding of suitable clays, their moulding, and proper fir- his Perseus and the Head of Medusa. ing—that gave the foundry the crucible for handling molten This three and a half ton statue was com- metals. Bells were generally decorated to give them an addi- pleted in 1554 and was unveiled at the tional message or to keep danger away, while cannons were Loggia dei Lanzi in Florence, Italy, where usually decorated with the coat of arms of the owner. it stands to this day. The process was developed to a high degree of excellence, The Lost Wax Process as is attested to by the many finely detailed statues, jewelry, and artefacts The lost wax process dates back thousands of years. The from antiquity. This technique was redis- artists and sculptors of ancient Egypt and Mesopotamia, the covered in 1897 by the dental profession Cellini’s Perseus and Han Dynasty in China, the Aztec goldsmiths of pre- for producing crowns and inlays. CIM the Head of Medusa

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metallurgy

History of Metal Casting—Part 2 by Fathi Habashi, Department of Mining, Metallurgical, and Materials Engineering, Laval University

Casting of Bells associated bells with pagan rites and beliefs, while in Judaic The development of the bell-casting skill ushered in the practice, the ram’s horn and the metal trumpet have always Bronze Age around 3,000 BC. Bells were frequently buried in been used. The casting of large temple bells in China the tombs of Chinese royalty and noblemen, but not in reached its zenith during the Ming dynasty (1368-1620). ancient Egyptian tombs. As metal-casting techniques The largest such bell, cast during the reign of the Emperor improved, the size of bells increased; bells weighing many Yon-gle (1403-1424), weighed 52 tonnes. tonnes were suspended in front of temples and palaces. Both Because bells were utiliezed so much in pagan cultures, drums and bells announced the time of day and warned of Christendom initially disapproved of them. It was not fires, floods, or an approaching enemy. The ancient Chinese until the second century that the bell was adopted as the were also successful in controlling the pitch of bells by con- symbol of preaching the gospel and used as a call to trolling the relationship between size and thickness. assemble. The popularity of bells increased enormously in Chinese bells were cast in a variety of forms. In addition the ninth century after being promoted by Charlemagne. to stationary bells, small ornate hand bells with clappers One of the earliest works describing the casting of bells were used in temple ceremonies. These are rung by and the problems of its harmonics was written by the Buddhist and Taoist priests during services, in conjunction Benedictine monk Theophilus Presbyter in the latter part with cymbals, gongs, and other instruments. It was believed of the eleventh century. This work and subsequent trea- that bells could cast or remove a spell and increase fertility. tises indicate the concern for proportions and the proper Muslims and Jews have refrained from using bells. Muslims mixture of copper and tin for producing the best ring, and how to change a bell’s pitch by varying its dimensions and wall thickness. Since the fifteenth century, it has been pos- sible to influence the musical tone of the bell through pre- cise design of its form. When larger bells were required, it became imperative to cast them in the church yard to eliminate their transport.

The Casting Method For casting large bells, the moulds were formed in deep pits directly in front of the furnace to simplify the pouring process. The process first called for the preparation of the core, usually formed with vertical sweeping, which con- sisted of a top and bottom bearing, the latter supporting a spindle on which the strickel board was mounted. The board was shaped to the interior contour of the bell. Loam, based on a brick interior, was plastered on until the board could be revolved with clearance. A new board was placed

A variety of forms of ancient Chinese bells. The barrel-shaped bell originated in the Chou Dynasty (1122-255 BC). Left: cope and core; centre: sweeping cope of bell mold in pit; right: furnace.

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on the spindle, Big Ben shaped to the outer After a fire destroyed the Palace of Westminster, the seat contour of the bell. of the British government, Parliament decided in 1844 that Clay was again the new building should incorporate a tower and clock. The added until the clock was completed and the bell was cast in 1858; it outer shape was weighed 13.76 tonnes. The Parliament had a special sitting attained. Rods were to decide on a suitable name for the great bell. During the placed in the mould debate and amid the many suggestions that were made, Sir for reinforcement Benjamin Hall, a large and ponderous man known affec- and the entire tionately in the House as “Big Ben,” rose and gave a long mould baked. speech on the subject. When he finished, a wag in the When the bells were chamber shouted out: “Why not call him Big Ben and have cast, the molten done with it?” The house erupted in laughter and the name metal was directed ‘Big Ben’ had been adopted. through a trough Casting of a large bell: 1) arbor brace; 2) bearing from the furnace Russian Bells board; 3) strickel board; 4) spindle; 5) brick work of into the gates. After After his marriage in 1472 to Sophia (Zoe) Palaeologus, core; 6) loam core face; 7) clay and wax bell pattern; 8) bell pattern; 9) cope; 10) pouring gate; 11) sup- cooling, the castings niece of Constantine XI, the last Byzantine emperor, Ivan III porting rods; 12) metal profile block; 13) baking fire. were removed. took interest in the development of the Kremlin. In 1474, he invited a group of skilled workers from Italy to introduce the Famous Bells Western techniques of casting. By 1533, an 18-tonne bell The Peace Bell, which weighs more than a tonne, is was cast in the Kremlin. The seventeenth century was the located in Peace Park in central Hiroshima. It is rung by vis- greatest period of Russian bell casting. In Moscow and its itors as part of their wish for peace. Just outside Sofia, suburbs there were about 4,000 churches, each having up to Bulgaria’s capital, is the Bell Garden containing a large num- as many as ten bells. On Paschal night, it was customary for ber of bells donated by different countries. the bell in the Tower of Ivan the Great to strike the first sound at midnight, followed by the ringing of the bells of all The Liberty Bell the other churches, announcing the Resurrection of Christ. In 1751, the Pennsylvania Assembly ordered a bell from The giant bell on display in the Moscow Kremlin is actu- a foundry in England to commemorate the 50th anniversary ally the last of the four bells that bore the nickname “Tsar- of William Penn’s Charter of Privileges, Pennsylvania’s orig- Kolokol” or “Tsar-Bell.” It was cast in 1599 during the reign inal Constitution, which speaks of the rights and freedoms of Boris Godunov and weighed 35 tonnes; however, it fell of people. The bell, however, cracked on arrival. It was then during a fire near the middle of the seventeenth century. Its given to a Philadelphia foundry for recasting. When the new metal was used in the casting of a second bell in 1654 that bell was raised in the belfry, apparently weighed 128 tonnes; however, it nobody was pleased with its tone. And so, cracked as well and fell into it was sent back to the foundry for recast- pieces when first tested. It was ing. The new bell, weighing 2,080 lb, again re-cast a year later, this time cracked in 1846. It achieved special status weighing 160 tonnes, but another when abolitionists adopted it as a symbol fire caused it to fall down and for the movement. crack in 1701. In 1730, Empress Anna Ivannovna gave the order to re-cast the remains of this bell into a new 220-tonne bell; how- ever, while it was in the pit, the scaffolding caught fire in 1737 and the bell fell. People started to pour water over it and as a result, the bell cracked and a big chunk fell off. By the mid-eighteenth century, the expansion of Russia to the east caused an increase in the demand for church bells in newly The Peace Bell The Liberty Bell developing villages, towns, and

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cities. Also, a new bell industry had emerged, that of small bells for horse carriages. Farmers along the new travel routes to Siberia started to cast horse bells in their farm- yards. At annual fairs, hundreds of bells were put on dis- play, suspended from scaffolding so that the customers could ring the bells and buy the ones to their liking. During World War I, over a hundred bells were sent from churches in the Baltic provinces and Poland to save them from the advancing Germans. Russian bell founding ended after the October Revolution in 1917. The state confiscated church bells and many were sold.

Other Bells The oldest bell in Korea was cast in 723 AD in the Shilla Dynasty. King Sung-Tug’s Great Bell was cast in 771 AD in the Chosen Dynasty and weighed about 22 tonnes; it is on display at the National Museum in Seoul. Korean bells were struck by wooden hammers. The Great Bell of Dhammazedi in Burma (now Myanmar) may have been the largest bell ever made. It was lost in a river after being removed from a temple by the Portuguese in 1608. It is reported to have weighed about 300 tonnes. One of the largest bells still in existence may be the Mingun Bell, located in the Mingun temple, Myanmar, which weighs 90 tonnes. The bell in St. Stephen’s Cathedral in Vienna was cast in 1711 from the metal of cannon iron balls used by the Turks during the siege of the city in 1683; it weighed 22.5 tonnes and was destroyed during World War II when the cathedral was damaged by fire. The new bell weighs 21.4 tonnes, was cast from the metal of the old bell in 1951 in the St. Florian foundry in Upper Austria, and was ceremonially trans- ported from Linz to Vienna. It is popularly called “Pummerin” because of its deep tone. It is the largest bell in Austria and the second largest in Europe, after the one in Cologne cathedral.

Bell Museum In 1599, Bartlme Grassmayr established the Bell Foundry in Innsbruck, Tyrol. His casting expertise was con- tinually improved and handed down from father to son. The foundry museum relates the history of bell casting. CIM

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metallurgy

History of metal casting–Part 3

by Fathi Habashi, Department of Mining, Metallurgical, and Materials Engineering, Laval University Casting of Cannons With the discovery of gun powder around 1250 AD, European bell founders turned to guns. During the sixteenth century, the production of cannons increased as armies came to appreciate their destructive power. As a result, monarchs became interested in casting cannons. For example, Maximilian I, the Holy Roman Emperor, established an arsenal in Innsbruck in 1505, now a museum, while Henry VIII (1491-1547) established an Ordinance Depot (later Royal Arsenal) at Woolwich in 1518. The inadequacies of early iron resulted in the use of bronze as a material for cannons. Early can- nons were cast hollow, using cores to create a rough but serviceable barrel that could be finished and smoothed by hand. However, the bores were often not round, which caused wide variations in range and accuracy because of the difficulty in aligning the core to the barrel during casting. It was Johan Maritz, Master Founder at Burgdorf, Switzerland, who, in 1713, designed a machine tool that was capable of boring cannon barrels from a solid casting. The method was time-consuming; however, it produced cannons with round, smooth, and parallel bores. When the Dutch Ordinance decided Above A gigantic cannon to adopt his tech- cast by Krupp in Germany, nique in 1747, on display at the Paris exhibition of 1867. Maritz moved to Right, clockwise the Netherlands from top left Casting of State Gun Foundry early cannons. in The Hague, Wrapping the arbor with Europe’s leading rope. gun producing After applying loam to the pattern, the mould is facility at the time. reinforced with iron Maritz’s sons later bands. introduced the Baking the cannon mould technique to over an open fire. France and Spain. Stages in the process: 1) arbor, 2) winch, 3) arbor and winch Monge and casting mounted on trestles, of cannons 4) partially wrapped arbor, 5) completely wrapped In the early days arbor. of the French Revolution, the serviceable artillery pieces were very small. In 1793, Napoleon appointed his friend, the mathematician Gaspard Monge (1746-1818), to lead a special commission to oversee the production of artillery. Monge abandoned the use of clay in favour of sand to decrease cost and improve the quality of the casting. He established gun foundries in churches and on farms throughout the French countryside, and instituted training programs intended to familiarize workers with the techniques and skills needed to implement the new methods to be

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From left to right Iron from the blast furnace flowing in sand moulds prepared on the ground and left to cool; Continuously moving casting machines used in making cannons. France produced 7,000 pieces for entire mould was then bound with iron bands and baked the army and navy in 1793-1794. Monge’s contribution to over a fire; the whole assembly turned on its arbor until the advancement of cannon production was recognized on completely dry. After cooling for a few days, the arbor was a French stamp issued in 1990. removed. A chaplet was used to hold the core in place. The breech was usually moulded separately and the whole job Iron cannons was assembled, breech down, in a pit before the furnace. Bronze possessed greater tensile strength than iron and could withstand bore pressures more readily when the Boring of solid cast cannons weapon was fired. On the other hand, it was much more A solid cannon was firmly secured horizontaly in a expensive than iron. This drove the research into improving water-powered machine designed specifically for boring. An the production of iron. In 1795, John Wilkinson (1728- iron boring bar with a steel cutting tool was advanced into 1808), the iron master of Soho Works in Stoke-on-Trent in the bore of the piece as the gun blank was turned by the England, designed a small shaft furnace that became known machinery. A series of cutting heads were used; the first was as a cupola in which he melted pig iron and other material small and subsequent heads increased incrementally in size to produce cast iron of better quality. With these improve- until the desired bore diameter was achieved. Boring typi- ments in the quality of iron, bronze was gradually replaced cally lasted for a period of days. by iron. His high-quality cannons were the reason for the British Navy’s superiority in battles. Boring cannons and the theory of heat The first cannons were the bombard type but these were In 1798, while manufacturing cannons for the Bavarian later replaced by barrel-type cannons that were bigger in military, Count Rumford (1753-1814) observed that grind- size. The early projectiles used were stone balls. Then, in ing used to hollow out the barrel produced huge amounts 1373, iron shot came into use, but only to a small extent of heat, which continued to flow with the borings as long as due to the high cost; they became widely used around 1600. the grinding was maintained. According to the theory at Explosive projectiles were later used. that time, the stress of rubbing surfaces together forced some caloric fluid to be pushed out from between the Casting of hollow cannons atoms, and it appeared as heat. Rumford, however, noted In casting the early cannons, an octagonal piece of tim- that the piece of metal must have contained an apparently ber known as arbor was used, around which straw rope was infinite amount of caloric fluid. He therefore came to the wound. Loam was pressed into the straw and smoothed by conclusion that the friction of grinding set the internal a strickle board, forming the outside of the cannon. invisible microscopic particles in the metal in motion, Trunnios were then applied and more loam added. The resulting in heat emitted as atoms came into contact.

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Beneath the pinch rolls is an oxy- acetylene flame, which cuts the emerging ingot into convenient lengths. A few years later, the same technique was introduced in the copper and aluminum industries. Epilogue Metals were cast by ancient people to produce ornaments, primitive agricultural tools, or arrow heads for hunting. The introduction of copper, bronze, and later iron was so important in the history of man that epochs are named Bronze Age and Iron Age to emphasize the shift from the Stone Age. The close ties between casting metals and pottery indi- cate that the two arts must have developed simultaneously. It was the potter’s art of handling suit- able clays and their proper firing Casting pig iron in ingots that gave the foundry man the crucible for holding molten metal. Rumford’s work did not however kill the caloric theory. It Centuries later, when gun powder was discovered, cast- was the physicist James Prescott Joule (1818-1889) who in ing changed hands from monks and church officials, who 1847 conclusively supported Rumford’s views—a turning were casting bells, to monarchs, who became interested in point in the history of science. casting cannons. In times of war, bells were usually confis- cated and cast into cannons. The artistic ornaments and Continuous Casting statues conserved in to museums, the gigantic bells, and the Iron from the blast furnace was allowed to flow in sand monstrous cannons that have been cast throughout history moulds prepared on the ground and left to cool. When are a testament to the skill of the metal founder. The new solidified, the pigs were then removed and the moulds technology of continuous casting reflects the response of reused. This process is no longer used because it involves industry to the need for a fast and reliable method to satisfy extensive manpower. Continuously moving casting the requirements of a developing society. CIM machines were then introduced; by the time the molten pigs were moved from one end to the other, they were solid- ified and dropped away from the moulds in the form of Suggested Readings pigs, which were then used to make cast iron in the cupola. Aitchison, L. (1960). A History of Metals. New York: Interscience. The bulk of the pig iron is transferred in the molten Berenguer Rodriguez, J., & González, L.A. (2004). Copper Art in the Andean World. Santiago: state to the steelmaking plant. Steel was usually cast in Museo Chileno de Arte Precolombino. ingots and when solidified, it was removed and put in a Biringuccio, V. (1943). De La Pirotechnia (published in 1540; English translation by C.S. Smith furnace to be heated to a determined temperature before and M.T. Gnudi). New York: American Institute of Mining and Metallurgy. transporting it to the fabricating mills. This meant han- Derry, T.K., & Williams, T.I. (1960). A Short History of Technology from the Earliest Times to AD 1900. New York: Dover Publications. dling a batch often during the cooling step. Introducing continuous casting solved this problem in 1960s. In this Johnson, R.E. (1993). The changing technology of artillery manufacture. CIM Bulletin 86, 156-161. Habashi, F., editor (1994). A History of Metallurgy. Québec City: Métallurgie Extractive process, the molten metal is continuously fed from a Québec/Laval University Bookstore. reservoir and is allowed to solidify rapidly in a mould so Knauth, P. (1974). The Metalsmiths. New York: Time-Life Books. that at any given time, there is only a small pool of molten Leibbrandt, A. (2001). Civilization and Copper—The Codelco Collection. Santiago: Corporación metal present at the top of the ingot. As the solidified Nacional del Cobre. ingot emerges, it is grasped by a set of rolls which regu- Simpson, B.L. (1948). History of the Metal-Casting Industry. Des Plains: American late its downward progress. The contraction of the freez- Foundrymen’s Society. ing metal causes it to pull away from the mould walls. Tylecote, R.F. (1976). A History of Metallurgy. London: Metals Society.

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