A number of years ago, a series of tests on electric welding was conducted at the Watertown Arsenal, and the following results were reported in the Transactions of the American Society of Mechanical Engineers for 1898:
Wrought-iron welds averaged from 5 per cent to 10 per cent below that of the plain bars and the fractures were either fibrous or slightly spongy.
Steel welds showed a strength of only from 20 per cent to 50 per cent of the original.
Steel welded to wrought iron showed a strength equal to the iron.
Copper showed a strength of from 90 per cent to 95 per cent of the original stock.
! Brass and wrought iron gave very uncertain welds and low strength.
Out of sixty samples welded, twenty-nine broke in the weld; seventeen, within two inches of the weld; eleven, within the range of moderate heat; and two broke near the grips of the testing machine. Some of the steel welds were almost as strong as the bars and some of the iron welds were of slightly greater strength than the bars; so it will be seen that welding by this system compares very favorably with other methods of welding.
There are several firms making butt- and spot-welding apparatus in this country today and it will pay the student to get data from all of them. The principal companies are the Thomson Electric Welding Company, Lynn, Mass.; Geuder, Paeschke & Frey, Milwaukee, Wisconsin; National Electric Welder Company, Warren, Ohio; Toledo Electric Welder Company, Cincinnati, Ohio; Winfield Electric Welding Machine Company, Warren, Ohio, and the Standard Welding Company, Cleveland, Ohio. All of these makers have certain forms of machines which are adapted to particular lines of products, and they make a specialty of designing machines for any service capable of being performed by this system of welding.