Puabi (commonly labelled Queen Puabi) was an important person in the Sumerian city of Ur, during the First Dynasty of Ur. A gold goblet with a double-walled vessel made for her was found in her tomb. Brazed with an alloy of 25% silver, the gold was called ‘electrum’. Gold brazing was known and skilfully practiced by the Sumerians, the first civilisation in the history of man in the 3rd century BC. The goblet, created for Puabi, was found still filled with green eye paint in the Cemetery of Ur (in modern day Iraq) by Sir Leonard Woolley between 1922 and 1934, and is one of the earliest surviving examples of a brazed joint. The upper portion is double-walled and the brazed joint is made around the periphery. The goblet is currently on display at the British Museum in London.

Other examples of early brazing include drinking vessels with handles attached to the body using a brazing technique originating in Troy around 2200 BC. Brazing was also commonplace in Egypt around this time. Modern brazing has its roots in the work of the early brazers, however, the process has been refined and in many cases automated for mass production of brazed metal items.

Brazing is now a commonplace metallurgy technique used to join two metal parts together by melting and flowing a filler metal into the joint, the filler metal having a lower melting point than the adjoining metal. Where early metallurgists accomplished brazing using a charcoal fire and blowpipe, modern techniques are refined, precise, scaled to industrial levels and can be automated or semi-automated. Torch brazing is the most common form of mechanised brazing, ideally suited for small production runs or specialised operations.

Brazing on a larger scale is undertaken in furnaces. It is an automated or semi-automated process widely used in industrial operations which is especially cost effective. There are many advantages of furnace brazing which include the ease in which it can produce large quantities of small parts that are easily jigged or self-locating, a controlled heat cycle which protects parts which may distort from localised heating, low unit cost, a protective atmosphere in the furnace which is either inert, reducing or vacuum which all protect the part from oxidation and, of course, the ability to braze multiple joints simultaneously.

Vacuum brazing in particular offers significant advantages, giving very clean, superior flux-free braze joints of high integrity and strength. Brazing has developed immensely from the initial blowpipe and charcoal methods used by the ancients into a modern scientifically understood and computer controlled industrial process. It remains one of the mainstays of metal joining used today. more »