Tis was part of a discussion on TOS, but I thought it was interesting - especially to those into historical details. The case itself appears to be one of alleged excessive profits from a defense contractor. But it also details the problems and issue that had to be addressed in manufacture of a (then) novel aluminum mag.
Some excerpts:
The most difficult part of the magazine to manufacture was the outer casing (also called the tube or box). Because light weight was always a goal, the tube was manufactured from aluminum instead of steel. Universal originally used T-O 6061 heat-treatable sheet aluminum, but found that the magazine tube distorted out of specification when this substance was heat treated. By trial and error, Universal found that aluminum with a magnesium content between 1.0% and 1.2% would hold its shape during heat treating, and found with difficulty an aluminum supplier able to deliver aluminum which consistently met this specification. Each shipment was inspected when it entered the Universal plant. The aluminum was then chemically analyzed to determine the magnesium content, and it was tested with a micrometer to insure a thickness of .04 in., ± .001.
The aluminum was then run through a series of 15 individual die-stamping operations. The dies used in these operations quickly wore to the point where they would no longer produce acceptable tubes. The dies thus required constant cleaning and sharpening. After the die-stamping operation, the tube was folded and formed.
The specifications for the magazine designated many dimensions as critical. The distance between the tube window and the magazine lips had to be held constant within .003 in. The tube rib dimensions had to be held within .002 in. The width between the tube lips, where accuracy was essential to prevent malfunction, had to be held within .001 in. However, even if each of the individual tolerances were successfully complied with, the finished magazine would often be unacceptable because of the error that resulted from the accumulated tolerances. Thus, Universal was forced to tighten its operational tolerances beyond those called for by the specifications, and, as a result, some dies and equipment had to be changed.
After the tube was formed, it was vapor cleaned in preparation for welding. Each magazine required five spot welds, applied in an area 3/8 in. wide and 3 7/8 in. long. Originally Universal subcontracted the welding, but because the subcontracting cost was so high (25¢ per weld) the company purchased its own welding machines and brought the welding in-house. Universal worked with its welding tip supplier to develop an electrode tip that could withstand the high temperatures necessary to weld aluminum. Universal also devised a staggered welding sequence to minimize shunting and began using steel mandrels to hold the tube in place.
Colt specified, during the early years of development, that one magazine in every five should be destruct-tested for weld defects. The test required the seam of the magazine to be peeled back and the weld pried apart. A magazine so tested was destroyed and had to be sold as scrap; it was useless for any other purpose. By 1964, only about 1% of the welds so tested proved to be defective.
Heat treating the aluminum tube created several problems. The treatment was necessary to bring the metal to a proper state of hardness. After an unsuccessful search for a subcontractor that could perform the treatment effectively, Universal built its own heat treating furnaces. The heat treating had to be controlled within 25°. While temperatures too hot caused melting and distortion, temperatures too low failed to achieve the desired hardness. The furnaces were constantly monitored to guard against these dangers.
Universal also developed special stainless steel mandrel racks that could, without themselves becoming distorted, brace the tube during heating. After some experimenting, Universal decided to form the tube slightly out of specification so that during the heat-treating process it would expand into specification. After treatment, the tube was artificially “aged” in an atmosphere created by Universal.
Fun fact that I learned today: “Okay Industries is owned and operated by Mr. Edward Okay, who had served as the production manager for Universal during the review periods.”
https://casetext.com/case/simmonds-precision-products-v-united-states