Re: Please end my confusion
- From: "G. De Angelis" <deangelistool@xxxxxxxxx>
- Date: Fri, 29 Jun 2007 20:55:40 -0700
On Jun 29, 8:11 pm, "plasticmoldedprodu...@xxxxxxxxx"
<plasticmoldedprodu...@xxxxxxxxx> wrote:
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
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.
G. De Angelis
Valhalla Grafix LTD
(401) 749-1209 www.valhallagrafix.com
.
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