What is an Original Equipment Manufacturer (OEM)?
OEM, or Original Equipment Manufacturer, is a term used to describe a manufacturer of new vehicles. This could be a universally known automaker like General Motors, a heavy duty truck manufacturer such as Freightliner, or a smaller manufacturer of specialty or commercial vehicles. Eagle additionally offers support for new trailer manufacturers.
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Aftermarket is an umbrella term for the collective network of vendors who design and sell vehicular components that are intended to replace the stock manufacturer's parts. When we say ‘aftermarket sales’, we are referencing sales to the spring shops and repair centers that service the end customer. These spring shops service used vehicles and offer replacement products such as new replacement springs. All Eagle springs sold via the aftermarket are designed to the equivalent standards of the OEM using the highest quality processes available. In some cases, we additionally offer heavy duty replacement springs (or the ability to add a taper leaf to the stock spring) which will increase the load carrying capacity of the suspension.
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Heat Treatment is a process in which an enormous furnace reaching up to 1800˚ heats the steel bars of a spring in order to prep the steel for shaping. Once the steel bars reach optimum temperature, they are placed onto ‘forms’ that bend or shape the hot steel for a specific part number. During the same process the steel rotates on a Gogan wheel which dips the steel into a quench oil bath.
After the quench oil bath, the shaped steel is placed into a draw furnace. The draw furnace heats the steel (although at much lower temperatures than original furnace) where the steel is tempered to a specific hardness before the final cooling process.
The steel bars are first heated up to 1800˚, then placed into the form for shaping
________________________________________________________________What is ‘Shot Peening’ and ‘Stress Peening'?
Shot Peening is a metal surface treatment where a controlled stream of small steel balls called “shot” is used to bombard the metal surface of each leaf of the spring. Each shot acts as a tiny peening hammer as it makes an impression on the surface of the metal. These impressions create residual compressive stresses at and slightly beneath the surface, which enable the component to better resist any fatigue or stress corrosion that it might be exposed to once in service.
Cracks will not initiate or propagate in a compressively stressed zone. Because nearly all fatigue and stress corrosion failures originate at the surface of a component, compressive stresses induced by shot peening can considerably increase a spring’s life. The specific properties of the residual compressive stress layer are dependent on the specific shot peening parameters and the tensile strength of the metal being shot peened. Most metals also will increase in surface hardness after shot peening.
Stress Peening is simply an alternative version of shot peening primarily used on parabolic springs and other highly stressed springs. Essentially, a load is applied to each individual leaf of the spring while they are shot peened with a typically larger size shot. This process significantly increases the residual compressive stress level that is achieved in the tension surface of the leaf and equates to a longer life for the spring.
The shot peening equipment specifications are custom tailored for each specific part number to optimize durability and resist stress corrosion
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A parabolic spring design is characterized by fewer leaves whose thickness varies from center to ends following a parabolic curve. In this design, inter-leaf friction is reduced because there is only contact between the spring leaves at the ends and at the axle seat area. Aside from a weight saving, the main advantage of parabolic springs is their greater flexibility, which translates into a smoother ride and longer life.
At the parabolic taper mill, two robotic arms work simultaneously; the first robot picks the hot plate off the conveyor and performs the tapering process. The second robotic arm then places the plate on a table where various forging operations follow.
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At Eagle Suspensions, each and every spring is quality tested before it leaves our shipping dock. One critical component of our quality verification process is the 100% preset and test. During the preset, the center of the spring is ‘bulldozed’ by a robotic arm until the arch of the spring is totally inverted. The load created by the bulldozer ‘presets’ it, while it also tests the spring can handle a load that far exceeds its stated load capacity rating.