There is an increasing use of light metals in forging process, such as aluminum alloy. Aluminum forging has been proved forging type in a wide of applications, especially for automotive industry. Compared with aluminum casting, aluminum forging is more reliable for the designer to consider when there is a requirement on strength. The design of aluminum forging can often provide the new part desired light weight and high strength at low cost. These characteristics make companies gradually replace their original parts with aluminum forging. 

So, why aluminum forging? What are the advantages?

Strength

When forged and heat treated, aluminum forgings exhibit some mechanical properties comparable with steel forgings. The strength to weight ratio is therefore far superior. For example, the 2014-T6 aluminum forging has a typical UTS of 485MPa, exceeding that of many grades of steel forgings, and all commonly used aluminum castings. Unlike casting, forging is always porosity free (forging vs casting) thus allowing relatively straight forward heat treatment processes that significantly improve selected mechanical characteristics. The lower cost 6061 aluminum forging attains typical values of 310MPa, which is also superior to, for example, A356 (or 601 type) aluminum casting whether that alloy is semi-solid cast, squeeze cast or gravity cast. Further fabrication by welding is also available with 6061 aluminium, allowing it available for many other applications.

This strength comparison shows that aluminum forging can obtain good strength while keeping the feature of light weight, better than aluminum castings and steel forgings. Due to this advantages, aluminum forging is normally designed to provide optimum grain structure to suit the application. A combination of hot and cold working the alloy can allow strength considerably in excess of the “typical value”, allowing a single process to greatly assist both static and fatigue test results, and so should be considered when assessing a new application.

Cost

When several manufacturing processes are viable from the functional perspective, cost will be a major considering factor. Tooling of aluminum forging is generally cheaper than tooling of aluminum die casting, and the production rate is higher. Offsetting this is generally higher raw material costs, associated with the necessary alloying of raw materials to provide desirable heat treatable characteristics. Consequently, many aluminium forgings are used in highly stressed applications, although this is not always the case.
Surface Finish

Awide range of surface finishes can be produced with forging, from very smooth surfaces to relatively sharp serrations, and this may facilitate further surface finishing or be a functional attribute of the part design. Some alloys, like 6061, have desirable anti-corrosion characteristics without any further surface treatment at all.

Design Flexibility

Unlike casting, not all shapes can be forged in aluminum alloy. Based on the fact that aluminum forgings will come out from a die, tooling designers will provide surprising flexibility on dimensions of final shape in forging equipments. When considering aluminum forging process, it is important to review the “manufacturability” of a proposed design as soon as possible in the design process to ensure that optimum contours are suggested. The increased use of 3D modelling packages and related 2D drawings allow a client to electronically transfer models to a forging business early in the design phase to have suggestions on, for example blend radii and parting-line position to provide optimum strength and die life. Fatigue life may be an issue in some applications, and so if a product is migrating from a steel equivalent, then a review of fatigue stresses may be desirable so that all performance criteria are met with a new aluminium part. Although most aluminium forging in China is “closed-die”, the history of aluminium forging sees a large number of very large “open die” forgings used in the aircraft industry. Consequently the physical size of the component may not restrict the use of a forged component although initially it may appear a daunting task.