Red-hot steel is run through a mill which rolls it to the proper thickness and width. It is heat treated and forged to the proper shape and tempered in a bath, (oil-water, etc.), as may be best suited to that particular steel.
The compounding of the steels used in making springs requires careful attention. Here experts who have made a study of steels and alloys are employed, and the men engaged in this work must generally have had college training.
Rolling mills and forge machines are handled by men who have been trained to operate them. A handicapped man could handle some of the machines, some of which require two good hands while others require but one hand. Some can be operated by men with one leg.
Springs are assembled after being matched and formed, and are then ready for shipment. In assembling springs they must be scaled and oiled. The oil is to prevent rust while the scaling is done to remove the shell-like crust that may form in tempering. The spring bolt bushings are also installed in this department. A man having one good leg and two hands could assemble springs. Spring work as a whole requires a great number of men, some of whom must be highly trained in their special work, while others need no special training. The work is inside, wages are good, and factories run practically the year round. Spring factories are usually located near large automobile centers. While some automobile manufacturers make their own springs, the majority purchase from spring factories.
PLAN No. 1124. FRONT AXLES AND SPINDLES
Front axles, unlike the frame, are forged instead of being pressed into shape. In the pressed steelwork the dies that shape the piece move slowly under great pressure. In the drop-forge work one die is stationary, and the other attached to a large weight operated by power is lifted several feet and released, striking the piece laid upon the stationary die a hard blow, and forging the metal into the shape. Before being placed in the drop forge machine the metal is heated in a blast furnace to the proper temperature.
Front axles are drop-forged from a solid bar of steel. They are forged into an I-beam form which gives them great strength. The end of the axle is forged into the shape of a fork or yoke.
This rough forge work is done by men who are capable of handling the weight of the axle and who can handle the machine. Care must be exercised or the dies will be ruined. Two to three men are usually necessary for each drop forge machine. They must bend the axle to proper shape while it is still hot. The axle is given a rough jig test before it goes to the heat-treatment department. After the axle is forged it goes to the heat-treatment department, where it is heated to take out any internal strain. In forging steel, the structure is disturbed and put under strain, and reheating of heat treatment relieves this strain, giving the steel greater strength.
The men who run these heat-treatment furnaces have been trained for this particular work, and they must move about freely and be able to handle the axles.
From the heat-treatment department the axle goes to the machine shop for the machine-work.