Being that most of my experience has been in fabricating and molding plastics, I have to admit a serious gap in knowlege regarding "temper" of a flat brass metal strip that has to be inserted into one of our molded plastic parts. I was always led to believe that it was as a result of heat imposed on metal to make it softer. Now i am asked to find the brass strip material with a "temper". If someone would be kind enough to give me a quick synopsis on it, I am beholding to you. David
On Jun 29, 8:11 pm, " snipped-for-privacy@yahoo.com" wrote:
David, Multiple meanings for a word, especially in the same Industry, can be confusing to most anyone. The word temper is used in the field of metallurgy, in that when a carbon steel is first quenched to be heat treated, it is too hard from the quench itself and has to be "tempered", which means that it has to be heated to a smaller amount of heat than was used in the initial heat treating of it, in order to relax the tightened molecules and thereby introduce some ductility into the metal, whereby from the quench, some metals can be hard like glass and subject to extreme cracking. Tempering is needed to remove this excessive hardness. The meaning of temper relative to non precious metals is somewhat different. Temper is just another word for Hardness of the metal. The most popular way to harden non ferrous metals is by compression. This is called "work hardening". Whether the metal be steel, brass, aluminum, or any of the copper alloys, or even the precious metals, silver and gold and their alloys, temper is accomplished by rolling from a thicker size down to a thinner one, and by compression of the molecular structure of the metal. Temper is measured in "numbers hard" denominations; for example 1 number hard would be dead soft, or annealed, and 9 numbers hard would be the hardest that the metal can be, or "spring temper". Everything in between is done to accommodate the particular application. Bottom line is that any method that would compress the metal, be it rolling, or hammering the metal from one thickness down to a thinner one is called "work hardness", thereby imposing "temper" to the material . A paralell to make you visualize this better would be : Rolling strip material down from a dead soft state of .020" thickness down to .010" may yield a metal that is 2 numbers hard. Rolling strip material down from a dead soft state of .
075" thickness down to .010" thickness, may yield metal that is 9 numbers hard, (spring temper). Some metal manufacturers use the terms 1/4 hard, 1/2 hard, 3/4 hard etc, in lieu of numbers. There are also a few (carbonless) metals that can be hardened by heat- treating. Cold roll steel can be heat treated by heat and dipping in arsenic, some of the 400 series of Stainless Steels can also be hardened by heat and quenching. I am not very familiar with these methods. I do know that these methods are usually practiced by professional Heat Treaters. I hope this helps you somewhat.
Brass is not tempered by heat treatment but by mechanical compression.
I remember making a brass ashtray during my apprenticeship, this was formed by forming a brass plate into a spherical shape on a leather sandbag by means of a ball pein hammer, this process is called planishing.
It leaves a finish of indents that have hardened the brass during shaping.
i have extracted this explanation from a clock makers site, they use brass a lot
......Finally we must mention the other common metal used in clocks, brass in its various forms. Brass is non-ferrous and cannot be hardened by heat treatment in the same way that carbon steel can. It will however harden by mechanical pressure and this is usually known as "workhardening". When brass is received in the soft state, such as in castings or soft sheet, it is often required to harden it before it is suitable for our work and this we do by hammering or rolling it. Conversely there are occasions when hard brass needs to be softened, perhaps so that if can be bent or riveted, and here heat treatment is used to anneal the brass. The metal is heated to a dull red heat and allowed to cool and this treatment will be found to soften the metal completely. In some books it is suggested that the brass should be quenched in water after heating but this is purely a matter of convenience in handling; rapid quenching will have no effect on the annealing process.
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