Cold Forging
Cold forging is a metal shaping & manufacturing process in which bar stock is inserted into a die and squeezed into a second closed die. The process, completed is at room temperature or below the...
Aluminum Forgings: Types, Processes and Applications
Introduction
This article contains everything you need to know about aluminum forgings, including how they are made, how they are used, and the types of aluminum alloys.
You will learn:
- What is an Aluminum Forging?
- Types of Aluminum Forging
- Uses for Aluminum Forgings
- Types of Aluminum Used for Aluminum Forging
- And much more�
Chapter 1: What is Aluminum Forging?
Aluminum forging is a method utilized to process aluminum alloys by exerting pressure and heat to manufacture robust and durable parts. This involves the pressing, pounding, or squeezing of an aluminum billet, workpiece, or cylinder under substantial pressure to create components with enhanced strength. The temperatures employed in the aluminum forging process range from just below to slightly above the recrystallization point, or sometimes even at normal room temperature.
All aluminum forging techniques are considered, including open and closed die forging and rolled ring forging. The selection of a specific forging technique is contingent on the type of product being manufactured and its intended use. Aluminum is exceptionally suitable for numerous applications because of its lightweight nature, strength, ruggedness, corrosion resistance, and forgeability.
The forgeability of aluminum alloys is compared against carbon steel and low alloy structural steel. At ambient temperature, aluminum alloys demonstrate lower deformation resistance compared to carbon steel, which possesses three defined deformation temperature intervals. Aluminum alloys are significantly responsive to temperature nuances, with deformation resistance altering with temperature fluctuations.
Although casting is a prevalent method for shaping aluminum, forging presents extra advantages by infusing deformation energy that refines and augments the alloy's metallurgy. Through forging, the internal microstructure of aluminum ingots is altered, voids and porosity are crushed, and recrystallization is triggered, enhancing the finished product's durability and toughness.
Chapter 2: What are the different types of aluminum forging?
The selection of the appropriate aluminum forging process is vital for harnessing the full potential of this lightweight yet durable non-ferrous metal. Aluminum forging plays a crucial role in various industries—such as automotive, aerospace, construction, marine, and electrical—where reducing overall component mass and improving reliability directly impact performance and efficiency. Aluminum, known for its excellent strength-to-weight ratio, malleability, corrosion resistance, and conductivity, is ideally suited for forging, which is a manufacturing process that shapes and forms metal into high-strength parts using compressive forces. The fundamental concept of forging is to apply pressure—either mechanical or hydraulic—to mold aluminum alloys into precise shapes and sizes that meet demanding engineering specifications.
Forging is broadly classified into hot forging and cold forging, depending on whether the material is forged above or below its recrystallization temperature. From these two base methods, advanced aluminum forging techniques have evolved. These include drop forging, press forging, upset forging, roll forging, rolled ring forging, isothermal forging, open die forging, and closed die forging. Each method is carefully selected based on aluminum alloy grades (such as 6061, 7075, or 2024), component design complexity, mechanical property requirements, production volume, and the final application's needs. Selecting the right forging process is crucial for producing high-performance, cost-effective, and reliable aluminum components used across diverse industries.
Cold Forging
With cold forging, aluminum alloys are shaped into intricate and complex forms without significant heat input. This method leverages the plasticity of aluminum—its ability to undergo permanent, high-precision deformation at room temperature while maintaining excellent surface finish and close dimensional tolerances. Since scaling is minimized and energy consumption is lower compared to hot forging, cold forging is an eco-friendly and economical option for high-volume production of precision aluminum parts.
Although aluminum parts can be produced via machining or cutting, these methods are slower, create substantial material waste, and require costly post-processing. Cold forging, however, achieves near-net-shape manufacturing, drastically reducing raw material waste and machining time. It accommodates highly detailed two-dimensional and three-dimensional designs, creating features such as holes, chamfers, pins, fins, steps, and even delicate geometrical patterns in a single, efficient operation. As a result, the production cycle is shorter while the quality and complexity of the output increase.
The core principle of cold forging involves placing an aluminum billet, bar, or workpiece—typically from ducal or high-plasticity alloys—between upper and lower dies and applying compressive force using mechanical or hydraulic vertical presses. The aluminum is deformed precisely to match the die cavity, providing exceptional dimensional accuracy. This advanced aluminum forming technique produces a wide range of finished products, including automotive alternators, starter motors, gears, transmission shafts, electrical connectors, anti-vibration mounts, sporting goods, motorcycle and bicycle components, and high-strength aerospace fasteners.
Key industries utilizing cold forged aluminum include automotive OEMs, electronics manufacturers, and manufacturers of lightweight, high-performance consumer products, where efficiency and repeatability are essential.
The advantages of Cold Forging Aluminum:
- High interchangeability and component reproducibility for mass production
- Smooth, even surface finish, minimizing the need for secondary finishing
- Precision dimensional control for tight tolerances
- Customized mechanical properties can be imparted
- No pre-heating required, reducing energy costs
- Reduced material waste and enhanced cost efficiency
- Superior grain structure increases fatigue resistance and part longevity
Hot Forging
Hot forging aluminum leverages elevated temperatures to maximize the metal’s ductility and workability while simultaneously enhancing its mechanical properties. This process produces forged aluminum products with a strength-to-weight ratio often outperforming basic steel, while maintaining the corrosion resistance and thermal conductivity for which aluminum is renowned. Hot forging is preferred for creating parts with intricate geometries, excellent structural integrity, and tailored surface finishes, ranging from smooth polished to sharp and textured profiles. It is the go-to aluminum forming process for high-stress aerospace, motorsport, and defense applications demanding exceptional reliability and performance.
During the hot forging process, aluminum workpieces are heated to their recrystallization temperature—typically between 350°C and 500°C (662°F to 932°F). This enables the forging equipment (such as drop hammers or hydraulic presses) to apply significant pressure, molding the workpiece into the die cavity and achieving the desired final shape. The combination of heat and pressure ensures reduced grain size, improved durability, and higher yield strength. The superior grain flow and structural integrity achieved via hot forging make it ideal for safety-critical components found in aircraft, automotive suspension systems, and heavy machinery.
Careful control of die and workpiece temperature is essential during hot forging to avoid strain hardening, cracks, and other defects. Maintaining appropriate heat distribution ensures the aluminum flows seamlessly within the die, yielding parts with uniform density and minimal porosity. Because of these benefits—including enhanced fatigue strength, excellent weldability, and high thermal and electrical conductivity—manufacturers frequently select hot forging for complex or high-volume projects where lightweight, high-strength components are needed.
Drop Forging
Drop forging is a high-speed metal shaping method in which aluminum workpieces are placed between precision die halves and compressed by repeated hammer blows. This dynamic technique is ideal for mass-producing strong and detailed aluminum components. In drop forging, the upper die is attached to a power-driven hammer, while the lower die rests on a stationary anvil. The heated aluminum—often from high-performance 6000 or 7000 series alloys—is struck until it flows and fills the entire die cavity. Any excess aluminum, known as "flash," is squeezed out along the parting lines and subsequently trimmed for material recovery and recyclability, further supporting environmentally sustainable manufacturing.
This method delivers products with superior mechanical strength, excellent toughness, and outstanding fatigue resistance by aligning the metal’s grain structure with the part’s geometry. Drop forging produces components with precise dimensional accuracy and consistency, making it an optimal solution for high-volume production of tools, automotive chassis components, precision sprockets, hardware, heavy-duty levers, and structural brackets. The resulting aluminum forging shows optimal resistance to wear and impacts, with minimal production waste and the flexibility to create complex, close-tolerance designs.
Rolled Ring Forging
Rolled ring forging is a specialized aluminum forging process used to create seamless, high-integrity rings from billets or cylinders. Initially, the billet is upset to increase its diameter while reducing its height, after which it is pierced to form a donut-shaped blank. This blank is then placed on a mandrel and shaped further by rollers, expanding its diameter and refining its wall thickness, all while preserving the continuous, defect-free grain flow that forged rings need for demanding service conditions.
This open die process operates at temperatures above the aluminum's recrystallization point, improving ductility and overall grain structure. The mandrel and rollers work in concert to achieve the required inside and outside diameters, wall thickness, and surface finish—all key factors for the part's final mechanical properties. Forged aluminum rings offer significant advantages over cast or welded rings, including improved tensile strength, shock resistance, impact performance, and long-term durability.
Forged rolled rings are widely used in the aerospace, wind energy, automotive, power transmission, and heavy machinery sectors due to their reliability and safety under extreme mechanical and thermal loads. Typical applications include jet engine turbine rings, helicopter gearbox rings, windmill components, pressure vessel end rings, and specialty equipment for hazardous or mission-critical environments.
Open Die Forging
Open die forging shapes aluminum by working billets or ingots between simple, flat, or contoured dies that do not fully enclose the workpiece. This forging technique is well-suited for producing large, custom aluminum components—such as discs, rings, cylinders, and shafts—with relatively simple geometries and excellent mechanical properties. The repeated impacts and plastic deformation involved in open die forging realign and refine the grain structure, significantly enhancing the toughness, fatigue resistance, and structural integrity of forged aluminum parts. The flexibility of open die forging allows the production of both small and massive custom components, with individual workpieces weighing from several pounds to several tons.
Open die forging is also an optimal solution for short production runs, prototyping, or crafting one-off specialty components for heavy equipment, construction machinery, energy systems, and aerospace. This method lends itself well to applications where superior metallurgical quality, low void content, and resistance to fracture under heavy loads are essential. The open die process may also serve as a pre-forming step, preparing aluminum ingots for subsequent closed die forging, extrusion, or machining to finer tolerances.
Forged products produced through open die forging exhibit improved machinability, outstanding wear properties, and performance that rivals or exceeds both cast and machined products in terms of density and reliability. The process also helps eliminate porosity, inclusions, and internal defects that can compromise safety and function in mission-critical parts.
Closed Die Forging
The process for closed die forging (also known as impression-die forging) utilizes specially machined dies that fully enclose the aluminum billet or blank during deformation. When the upper and lower dies come together, they shape the aluminum to obtain detail-rich profiles and strict dimensional accuracy. Closed die forging can be performed in either a single or multiple stages, depending on the part’s complexity and design requirements. This method works especially well with high-strength heat-treated aluminum alloys—such as 6061, 7075, and 2024—which are widely used in aerospace and performance automotive sectors where precision, safety, and consistency are paramount.
During the closed die forging process, skilled operators or automated forging lines control the force and motion of the dies to achieve grain flow alignment with anticipated service loads. This refining of the billet’s microstructure enhances strength, fatigue resistance, and shock tolerance. Once stamped, the product may only require minimal secondary machining or finishing, minimizing production time and cost.
This forging process is ideal for high-volume production runs because once the dies are manufactured, each part produced features near-identical quality, tightest possible tolerances, and excellent surface finish—significantly decreasing material waste and post-processing costs. Closed die forging can efficiently create parts including connecting rods, precision gears, linkages, suspension parts, brackets, and safety-critical aerospace components.
In summary, closed die forging boosts the cost-effectiveness, consistency, and mechanical properties of common and specialty aluminum products. Eliminating voids and porosity, the process ensures engineered aluminum parts meet the high-impact, lightweight, and fatigue-resistant requirements of modern industries.
Leading Manufacturers and Suppliers
Chapter 3: What types of aluminum are commonly used for aluminum forging?
The range of aluminum options for forging continues to expand, thanks to aluminum's lightweight nature, resistance to corrosion, and excellent strength-to-weight ratio. However, not all types of aluminum are suitable for forging, making it essential to carefully select the appropriate aluminum alloy for a given project. Among the various aluminum alloys available, the 6000 series and 7000 series are the most commonly used for forging.
Choosing the right aluminum alloy for a project depends on several key factors, including the intended application of the product and the specific properties required. Six critical factors should be considered when selecting an aluminum alloy for forging.
- Cost � Although cost is an obvious consideration, it may not be the most important part of the selection process since the design and nature of a product may require a higher quality of aluminum alloy. Manufacturers work with their clients to assist the clients in selecting an aluminum alloy for forging that is economical and is the best fit for a client’s needs.
- Strength � Forged aluminum parts that will be subjected to stress, heavy loads, and harsh conditions require high strength alloys that are capable of withstanding the load requirements and conditions.
- Corrosion Resistance � All aluminum alloys have corrosion resistance to a certain degree. Although this is true, certain alloys have lower resistance due to the compounds used to produce them. An evaluation of the environment where a product will be used can be a major determining factor when choosing an alloy.
- Weldability � The weldability of aluminum alloys varies from very weldable to unweldable in certain conditions. The factors that make welding aluminum difficult are its oxide layer and thermal conductivity, which influence the level of heat energy necessary to weld aluminum. During the initial selection process, manufacturers learn whether welding will be involved in a project and assist clients in selecting a weldable alloy.
- Machinability � Depending on the forging process and the design of a product, some aluminum alloys may necessitate machining to achieve the required tolerance. There is a wide selection of aluminum alloys that can be machined, to a certain extent. The amount of machining plays an important part in which alloy to choose.
- Thermal Properties � Most aluminum alloys have good thermal conductivity, which is three times greater than that of steel, a factor that makes it an excellent material for cooling and heating applications. Various grades of aluminum alloys are excellent at dissipating heat, making them ideal choices for applications that require the removal of heat.
Aluminum Alloys Used for Forging
Similar to other metals, a variety of aluminum alloys can be selected for manufacturing forged products. Over the 170 years since its introduction, aluminum alloys have become the most extensively used industrial metals, with millions of tons produced annually from both new and recycled sources. Understanding the different aluminum alloys and their properties is essential for choosing the most suitable alloy for a given project.
Aluminum Alloy 6061
Aluminum alloy 6061 is part of the 6000 series of aluminum alloys that have the number 6 indicating that the primary alloys in the series are magnesium and silicon, which are present in greater quantities than the other alloying elements. The composition of 6061 is 98% aluminum, 1% magnesium, 0.6% silicon, 0.28% copper, and 0.2% chromium with an assortment of small quantities of other elements.
Aluminum 6061 is known for its weldability, machinability, corrosion resistance, and workability. This alloy comes in various tempered grades, including 6061-O, 6061-T4, and 6061-T6. The designation following 6061 specifies the tempering treatment the alloy has undergone. The letter 'O' indicates that the aluminum has been annealed, while T4 and T6 grades denote higher yield strength due to their specific heat treatments and aging processes.
Aluminum Alloy 6063
Aluminum alloy 6063 is a medium-strength alloy renowned for its architectural applications due to its suitability for intricate and complex designs. Like 6061, alloy 6063 comes in T4 and T6 tempered grades. Being part of the 6000 series, it primarily contains manganese and silicon, with manganese enhancing strength and silicon lowering the melting point.
Alloy 6063 is ideal for applications requiring both lightweight properties and strength. Its low density allows for the formation of complex shapes without adding excessive weight, contributing to its widespread use. Additionally, 6063's lack of copper content provides superior corrosion resistance compared to other aluminum alloys. It also boasts excellent weldability.
Known as architectural aluminum, 6063 can be soft anodized to achieve a visually appealing colored finish, making it popular for building applications. Its resilience to harsh weather conditions further supports its use in demanding environments.
Aluminum Alloy 6082
Aluminum alloy 6082 is a medium-strength alloy, notable for its superior structural strength compared to other 6000 series alloys. This exceptional strength is attributed to the high manganese content, ranging from 0.4% to 1%, which influences the grain structure and enhances the alloy's ability to withstand higher stress levels. This increased strength also improves its machinability.
Despite its high structural strength, alloy 6082 is not typically used for architectural or aesthetic applications due to its poor anodizing qualities. Instead, it is favored for construction purposes, including scaffolding, bridges, transportation, and engineering applications. Like other 6000 series alloys, 6082 is available in various tempering grades, including O, T4, and T6.
Alloy 6082 is valued for its weldability, brazability, corrosion resistance, formability, and machinability. It is commonly used in forms such as rods, bar stock, and machining stock. Though relatively new, the T6 variant of alloy 6082 is widely used in the automotive, aviation, and high-speed rail industries. Its properties make it particularly suitable for hot forging, allowing the production of aluminum products with diverse dimensions. The alloy's excellent processing performance, corrosion resistance, dimensional stability, ease of coating, and effective oxidation further contribute to its versatility.
Aluminum Alloy 7075
Aluminum alloy 7075 is coveted as the highest strength alloy of all the aluminum alloys. Unlike 6000 series aluminum alloys, alloy 7075 has zinc, copper, and magnesium as alloying elements to create strength of 83,000 psi and resistance to stress corrosion cracking, which makes alloy 7075 an excellent material for use in high stress structural applications. Its forgings have superior static strength for use in airframe construction and stressed aircraft parts. The tempered series of alloy 7075 are T6, T651, T7351, and T76.
Alloy 7075-T6 is known for its highest strength among aluminum alloys, though it has lower toughness and resistance to stress corrosion cracking, making it unsuitable for cryogenic applications. Alloy 7075-T73, while offering improved resistance to stress corrosion and exfoliation, sacrifices some of the strength found in the T6 temper. The high strength, low density, excellent thermal properties, and ability to achieve a polished finish make alloy 7075 particularly popular in mold tooling applications.
The 7000 series aluminum alloys, including 7075, are extensively used in transportation applications due to their exceptional strength. Alloy 7075 was originally employed in the construction of fighter jets, contributing to their superior maneuverability. Its high strength has led to its adoption in various products, such as rock-climbing gear, bicycle components, skate frames, lacrosse stick shafts, and hang glider frames. Additionally, alloy 7075 is utilized in the military sector for manufacturing the M16 and AR-15 rifles.
The four aluminum alloys discussed are just a small selection of the numerous alloys available for aluminum forging. These alloys are among the most commonly used due to their essential properties, including strength, durability, corrosion resistance, toughness, and ductility. Their characteristics make them particularly suitable for various forging applications.
| Types and Mechanical Properties of Forgeable Aluminum Alloys Key - ◎ Excellent - 🞅 Good - △ Fair - 🞩 Poor |
|||||||
|---|---|---|---|---|---|---|---|
| Desired Properties | Material | Si Content (MASS%) | Mechanical Properties | Forgeability | |||
| Former Sumitomo Designation | Temper | Tensile Strength (N/mm)² | Proof Stress (N/mm)² | Elongation (%) | |||
| High Strength | 6061 | T6 | 315 | 275 | 19 | ◎ | |
| SG210 | T6 | 400 | 360 | 18 | ◎ | ||
| GS310 | T6 | 390 | 345 | 18 | ◎ | ||
| 2011 | T8 | 410 | 315 | 15 | ◎ | ||
| 2014 | T6 | 480 | 275 | 22 | ◎ | ||
| 2017 | T4 | 440 | 275 | 22 | ◎ | ||
| Abrasion Resistance | 4032 | T6 | 12 | 380 | 315 | 9 | 🞅 |
| SC100 | T6 | 10 | 440 | 390 | 8 | 🞅 | |
| SC300 | T6 | 10 | 480 | 420 | 8 | 🞅 | |
| SC150 | T6 | 15 | 420 | 390 | 2 | △ | |
| High-Temperature Strength | 2618 | T6 | 440 | 370 | 10 | ◎ | |
| CG29 | T6 | 520 | 400 | 14 | ◎ | ||
Chapter 4: What are the benefits of aluminum forging?
Forging is an ancient metalworking technique that has been utilized for centuries to create items ranging from weapons and cutlery to cookware, jewelry, and structural supports. Originally, the process involved hammering metal on an anvil with heat to shape it. While modern forging methods have become technologically advanced, they still incorporate some of the fundamental techniques used by early metalworkers.
Surface Finish
A key advantage of using aluminum for manufacturing components is its smooth, even, and attractive finish, similar to polished silver. While the forging process often yields products with this desirable finish, it can also produce surfaces with sharp serrations and jagged peaks. These variations may necessitate additional finishing or be integral to the product’s intended function and use.
Design Flexibility
The outcome of aluminum forging is heavily influenced by the design and configuration of the die used in production. Aluminum design engineers take client specifications to create dies with precise dimensions and configurations for forging the desired products. The main constraint of the process is the manufacturability of the design. Computer-aided design (CAD) technology allows for pretesting of designs before actual production begins, ensuring feasibility and precision.
Strength
Aluminum forging creates components, parts, products, and instruments that exhibit superior strength compared to those produced through casting and machining. The forging process aligns the grain structure of the component with its shape, thereby enhancing its strength and durability. Forged aluminum is particularly well-suited for applications that demand high resistance to repetitive loading, frequent impact, and harsh conditions, thanks to its exceptional impact resistance and strength.
Cost
Aluminum forging is typically less expensive compared to other manufacturing processes when factors like material cost and lead times are equal. The tooling required for aluminum forging is generally more affordable than that for aluminum die casting, and the process yields a higher production rate.
Mechanical Properties
Forging enhances the mechanical properties of aluminum alloys by altering their microstructure. This results in increased tensile strength, yield strength, toughness, and fatigue resistance.
Durability and Reliability
Unlike other aluminum forming methods that may produce products with porosity and voids, aluminum forging utilizes compressive forces to eliminate these imperfections. This results in increased durability, performance, and reliability of the final products.
Dimensional Accuracy
Aluminum forging avoids issues with shrinkage by heating the metal to just below or above its recrystallization point. The billet or workpiece is processed in its solid form, ensuring precise dimensional accuracy and integrity.
Property Reliability
One of the key advantages of aluminum forging is the retention of aluminum's exceptional properties. Despite the shaping and manipulation involved, the forging process does not compromise any of aluminum’s beneficial characteristics.
Material Waste
Modern manufacturing emphasizes reducing waste, and aluminum forging supports this goal. The flash produced from open and closed die forging can be easily reused and recycled, minimizing waste. Aluminum is highly recyclable and can be processed repeatedly without loss of quality.
High Volume Production
Aluminum forging excels in high-volume production, efficiently creating thousands of complex and intricate shapes in a short period. The timeline from design introduction to finished product delivery can be as brief as two months or less, with minimal waste generated despite large production quantities.
Conclusion
- Aluminum forging is a process that places aluminum alloys under pressure to form high strength, durable parts. The process of aluminum forging involves pressing, pounding, and squeezing an aluminum billet under great pressure to create parts that have high strength.
- The choice of the forging process for aluminum is to ensure that components have all of the positive properties of aluminum where weight and mass must be minimized and reliability is a necessity.
- In general, forging is used to form metals that have been heated to just above their recrystallization temperature and metals that are shaped at room temperature, which are the distinctions between hot and cold forging.
- It must be understood that not all aluminums can be used for forging, which necessitates careful selection of the type of aluminum to be used for a project.
- In the 170 years since its introduction, aluminum alloys have become the most widely used industrial metal with several million tons of it being used every year including new and recycled aluminum.
