Selected Metals - 6: Aluminum
|WARNING: Machine tools present a safety hazard. Improper operation can result in severe injury. These topics are for non-laboratory study only and are not to be used in conjunction with the operation of any tool or machine described herein. Never use a machine tool without the supervision of a qualified instructor.|
|In 1825 Hans Christian Oersted, a Danish chemist, had extracted tiny amounts of aluminum powder from alum (aluminum potassium sulfate mined from the earth). He was the first person to do so. However aluminum making was not an economical process until 1889 when American, Charles Martin Hall, patented an inexpensive method (below) for the production of aluminum, which brought the metal into wide commercial use.|
Aluminum, is not useful in its pure state so it must be alloyed with magnesium and one or more of the following elements: copper, silicon, manganese, chromium.
Annealed aluminum is much too soft and gummy for machining so the machinist usually gets the material after it has been heat treated. This is quite the opposite of most machine shop steels which are usually machined before heat treating. The type of treatment (called temper) is appended to the alloy number as one of the following designator letters:
The T temper has ten subdivisions numbered 1-10 that denote the specific process of the thermal heat treatment used. The T temper is the most common designator found in machine shop aluminum.
The following three alloyed aluminums are familiar to machinists: (the machinability characteristics are comparisons of aluminum to aluminum, not comparisons of aluminum to steel.). The American Standard for Metals (ASM) designation is in parenthesis.
A92024 (ASM 2024)
A96061 (ASM 6061)
A97049 (ASM 7049)
label: stainless steel, aisa, sae, aluminum, copper, tool steel, history of metal,