Milled coinage in the context of "Coin die"

A mint is an industrial facility which manufactures coins that can be used as currency.

The history of mints correlates closely with the history of coins. In the beginning, hammered coinage or cast coinage were the chief means of coin minting, with resulting production runs numbering as little as the hundreds or thousands. In modern mints, coin dies are manufactured in large numbers and planchets are made into milled coins by the billions.

Ancient Chinese coinage includes some of the earliest known coins. These coins, used as early as the Spring and Autumn period (770–476 BCE), took the form of imitations of the cowrie shells that were used in ceremonial exchanges. The same period also saw the introduction of the first metal coins; however, they were not initially round, instead being either knife shaped or spade shaped. Round metal coins with a round, and then later square hole in the center were first introduced around 350 BCE. The beginning of the Qin dynasty (221–206 BCE), the first dynasty to unify China, saw the introduction of a standardised coinage for the whole Empire. Subsequent dynasties produced variations on these round coins throughout the imperial period. At first the distribution of the coinage was limited to use around the capital city district, but by the beginning of the Han dynasty, coins were widely used for such things as paying taxes, salaries and fines.

Ancient Chinese coins are markedly different from their European counterparts. Chinese coins were manufactured by being cast in molds, whereas European coins were typically cut and hammered or, in later times, milled. Chinese coins were usually made from mixtures of metals such copper, tin and lead, from bronze, brass or iron: precious metals like gold and silver were uncommonly used. The ratios and purity of the coin metals varied considerably. Most Chinese coins were produced with a square hole in the middle. This was used to allow collections of coins to be threaded on a square rod so that the rough edges could be filed smooth, and then threaded on strings for ease of handling.

Hammered coinage was the most common form of coins produced from the invention of coins in the first millennium BC until the early modern period of c. the 15th–17th centuries, contrasting to the cast coinage and the later developed milled coinage.

The cash or qian was a type of coin of China and the Sinosphere, used from the 4th century BC until the 20th century, characterised by their round outer shape and a square center hole (Chinese: 方穿; pinyin: fāng chuān; Jyutping: fong1 cyun1; Pe̍h-ōe-jī: hong-chhoan). Originally cast during the Warring States period, these coins continued to be used for the entirety of Imperial China. The last Chinese cash coins were cast in 1912, the first year of the Republic of China. Generally most cash coins were made from copper or bronze alloys, with iron, lead, and zinc coins occasionally used less often throughout Chinese history. Rare silver and gold cash coins were also produced. During most of their production, cash coins were cast, but during the late Qing dynasty, machine-struck cash coins began to be made. As the cash coins produced over Chinese history were similar, thousand year old cash coins produced during the Northern Song dynasty continued to circulate as valid currency well into the early twentieth century.

In the modern era, these coins are considered to be Chinese "good luck coins"; they are hung on strings and round the necks of children, or over the beds of sick people. They hold a place in various traditional Chinese techniques, such as Yijing divination, as well as traditional Chinese medicine, and feng shui. Currencies based on the Chinese cash coins include the Japanese mon, Korean mun, Ryukyuan mon, and Vietnamese văn.

The Castaing machine is a device used to add lettering and decoration to the edge of a coin. Such lettering was necessitated by counterfeiting and edge clipping, which was a common problem resulting from the uneven and irregular hammered coinage. When Aubin Olivier introduced milled coinage to France, he also developed a method of marking the edges with lettering which would make it possible to detect if metal had been shaved from the edge. This method involved using a collar, into which the metal flowed from the pressure of the press. This technique was slower and more costly than later methods. France abandoned milled coinage in favour of hammering in 1585.

England experimented briefly with milled coinage, but it wasn't until Peter Blondeau brought his method of minting coins there in the mid-seventeenth century that such coinage began in earnest in that country. Blondeau also invented a different method of marking the edge, which was, according to him, faster and less costly than the method pioneered by Olivier. Though Blondeau's exact method was secretive, numismatists have asserted that it likely resembled the later device invented by Jean Castaing. Castaing's machine marked the edges by means of two steel rulers, which, when a coinage blank was forced between them, imprinted legends or designs on its edge. Castaing's device found favour in France, and it was eventually adopted in other nations, including Britain and the United States, but it was eventually phased out by mechanised minting techniques.