Forged rims gets its name from the process of forging a single piece of aluminium into the shape of the wheel rims.
Forged wheels do tend to carry a higher price tag than cast wheels due to the expense of the forging process. However, they provide greater long-term value thanks to their superior structural integrity.
No other metalworking components (including castings, machined bars and plates, weldments, and other fabricated assemblies) permit this degree of grain control and subsequent property enhancement. In castings, grain flow cannot be optimized since grain direction is characteristically random as a result of the solidification process. Similarly, machined components exhibit discontinuous grain flow. Because of extensive metal removal, grains are broken at the part surface, and the surface is where facture usually initiates.At best, grain orientation in machined parts is unidirectional, taking on the prior patterns of the original bar, billet, or plate.
Orientation of grain flow-alignment of the metal microstructure with the geometry of the part being forged is directly responsible for developing maximum tensile strength, toughness (impact strength), fatigue resistance and, ultimately, the greater service life expectancy that is characteristic of forged netshaped parts. In most forgings, the initial grain flow direction (longitudinal and the strongest) is oriented within the part along the axis that will see the highest in-service loads. However, grain-flow modifications made by judicious use of tooling and forging techniques can be utilized to maximize strength in other directions without sacrificing properties along the principal direction.
Some metals and alloys exhibit a “grain-flow sensitivity,” which is reflected by the degree of isotropy of the material being forged. Materials with high grain-flow sensitivity exhibit greater differences in properties between the longitudinal and transverse grain-flow directions. (This does not imply that forgings are strong in only one direction, since tests show that properties in any direction usually exceed those of non-wrought products, like cast- ings.)
Reduced testing is another important benefit derived directly from the integrity of forgings.The extreme strain rates generated during forging immediately identify the presence of defective raw material so that forgings are virtually “self-testing.” Because of the part-to-part uniformity of forgings, manufacturers do not have to ascertain the quality of every incoming component before putting parts through further in-house processing. This benefit is especially important with outside purchased components that are subsequently machined. While forgings readily lend themselves to quality control sampling plans, many castings need to be 100% tested to ensure their integrity.
Design engineers routinely find they can take greater advantage of the ultimate property values of forgings
Unique design can be achieved because of less material is required to create wheels via the forging process resulting in a lighter product than comparable cast wheels. Forged wheels are also stronger than their cast counterparts, which means forged wheels can be made in larger sizes that cast wheels can’t support.