Manufacturing Process.
Raw Materials.
The raw material which is used to create the spring of shock absorber is alloy spring steel. It is an AISI 6150 steel which is also commonly known as Chromium-vanadium steel. It is composed of (in weight percentage) 0.48-0.53% Carbon (C), 0.70-0.90% Manganese (Mn), 0.035%(max) Phosphorus (P), 0.04%(max) Sulfur (S), 0.15-0.30% Silicon (Si), 0.80-1.10% Chromium (Cr), 0.15min% Vanadium (V), and the base metal Iron (Fe). .
The Manufacturing Process.
The following description focuses on the manufacture of steel-alloy, coiled spring. .
1. Coiling.
Hot winding. Thicker wire of measured diameter is coiled into springs after the metal is heated to make it flexible. Standard industrial coiling machines can handle steel bar up to 3 in (75 mm) in diameter, and custom springs have reportedly been made from bars as much as 6 in (150 mm) thick. The steel is coiled around a mandrel while red hot. At this stage, the steel is too brittle to function as a spring, and it must subsequently be tempered.
2. Quenching.
Then, the coiled metal it is immediately removed from the coiling machine and plunged into oil to cool it quickly and harden it. The steel was heated to Austenitic region. When suddenly quenched, the Martensite is formed. This is a very strong and brittle structure. Thus, the spring needed to be temperered.
3. Tempering.
To increase the toughness of the spring, it has to be reheated to a pre-determined temperature that produces a finished hardness that will resist sagging, while being ductile enough to avoid breakage. According to Foundation of Materials Science and Engineering by William F.Smith and Javed Hashemi book, the alloy steel have to be tempered in temperature between 400-700°C to become a spherodite steel which is a good choice of metal condition to withstand shock.
Finishing.
I. Grinding. If the design calls for flat ends on the spring, the ends are ground at this stage of the manufacturing process.
