Simple and complex metal parts are found in various industries around the globe. From complex aerospace assemblies to simple garden tools used to beautify our lawns, numerous metal products are created using a metal forging process that makes the materials strong and durable enough for the task at hand.
Typical metals used in the forging process include carbon, alloy steels, aluminum, stainless steel and copper alloys. Selecting the appropriate metal ensures that the forged product will meet design specifications and be crafted to the necessary quality. In addition, you want to select a metal that will work for the specific application without experiencing any negative effects such as corrosion, extreme wear and tear, or mechanical failure.
How the Metal Forging Process Works
Manufacturers forge metal by using heat combined with compression methods, such as rolling, hammering, and pressing, until the metal takes the desired shape. There are different methods for forging metal, with each providing different advantages to the production line. Common methods may include:
- Drop forging. Drop forging involves using a hammer and a die to mold the metal into the desired shape. Drop forging may use either open or closed dies, depending on the project details.
- Press forging. Press forging uses multiple dies instead of one die as is used with a hammer. Continuous, slow pressure is applied using hydraulic or mechanical means until the metal takes the desired shape.
- Roll forging. Also known as roll forming, roll forging involves the use of cylindrical or semi-cylindrical rolls with shaped grooves that compress a metal bar into the required shape.
The above methods are often combined with heat to make the metal more ductile. Hot forging allows the manufacturer to change the mechanical and structural properties of the metal to provide certain qualities, such as tensile strength or ductility. This method can also help to further remove impurities in the metal that could cause voids or cracks.
What Metals Can Be Forged?
Determining what metals can be forged will depend largely on the provider that you hire and their production capabilities, though technically, all metals can be forged. Each metal has different properties and reactions when heated or forged using certain methods. Due to these differences, some manufacturers will specialize their processes to work with specific metals, such as aluminum, steel, or titanium.
Here are some common metals used in metal forging.
- Alloy steel. Alloy steel is a broad term referring to a variety of steels that have had their properties altered or enhanced by alloying the steel with additional metals, such as silicon, manganese, or nickel. These added metals may provide specific characteristics such as corrosion resistance, malleability, or thermal/electrical conductivity. Alloy steel offers exceptional wear
resistance and strength for forging metal parts.
- Aluminum. Aluminum has good corrosion resistance, allowing it to be used in challenging environments, such as those found in aerospace applications. The metal also has good stability at lower temperatures and its low density gives it a favorable strength-to-weight ratio.
- Carbon steel. Carbon steel contains higher levels of carbon to offer more increased strength than regular steel. The metal also performs well in high-temperature and high-pressure applications.
- Microalloy steel. Microalloy typically contains additives of vanadium, titanium, or niobium. Microalloy steel develops excellent toughness as it cools, and typically does not require post heat treat to achieve increased mechanical properties.
- Stainless Steel. Stainless steel has exceptional corrosion resistance, heat resistance, strength, and durability. All of these properties get further enhanced when the metal undergoes a forging process.
- Titanium. Titanium is a lightweight metal with exceptional strength. The metal offers superior resistances to corrosion and high temperatures.
Metal Forging from Cornell Forge
Deciding on the right metal to use will depend on your part and how it will function in its intended application. If you need help selecting the right metal for your product, the team at Cornell Forge can help. Our metallurgist and technicians are knowledgeable regarding available forging techniques and how each method will interact with specific metal materials. Please contact us with any questions or request a quote today.
Forging changes a metal workpiece through compression at either cold, warm, or hot temperatures. Cold forging improves the strength of the metal by hardening it at room temperature. Hot forging results in optimal yield strength, low hardness, and high ductility by hardening the metal at extremely high temperatures. Whether to use hot or cold forging depends on the finished component’s function, industry, and production volume.
Hot Vs Cold Forging
While cold forging compresses metal at room temperature, hot forging requires high heat. A primary differentiator of cold and hot forging is that the high heat of hot forging allows the metal to take on more elaborate and complex forms than cold forging.
The hot forging temperature varies depending on the type of metal. Hot forging starts with heating the dies to prevent any loss of temperature during the process and ensure crystallization doesn’t occur until forming is complete. Heating causes the metal to become more ductile. When the pressure of the dies squeezes the hot metal, the structure transforms into a more refined grain that results in increased yield strength and ductility.
Factors to consider when hot forging include:
- Cooling. If the metal cools to a temperature lower than the minimum threshold, it completes the forging. The metal must be reheated if this occurs before achieving the final shape.
- Tolerances. Dimensional tolerances with hot forging are less precise than cold forging.
- Dies. Hot forging dies are custom-made to the customer’s part specifications.
Cold forging uses a displacement process to shape the material into the desired shape. Compressive force squeezes the metal between a punch and die at room temperature until the material conforms to the die’s contours. Cold forging techniques include rolling, pressing, drawing, spinning, heading, and extruding.
Factors to consider when cold forging include:
- Material volume. Careful control over the material volume prevents stress and damage, particularly in closed forging, as the excess has nowhere to escape.
- Bonderizing. This coating process improves material flow during the process to reduce force, stress, and friction while improving surface quality.
- Annealing. Annealing softens the metal, improving the material flow. It can be applied as an intermediate process when work hardening occurs before the forging process is completed.
- Lubrication. Lubrication is critical during cold forging. High-viscosity oil protects against metal-on-metal friction and applying thin oil dissipates heat.
Advantages & Disadvantages Of Hot And Cold Forging
Advantages of hot and cold forging include:
- Hot forging. Increased ductility for more complex parts and allows for more options for customization
- Cold forging. Creates no waste, requires little to no finishing work, maintains dimensional accuracy, and results in high surface quality.
Disadvantages of hot and cold forging include:
- Hot forging. Additional cost for heat treatment, less precise dimensional tolerance, risk of warping
- Cold forging. Few options for customization, risk of residual stress, may require heat treatment
High Quality Forging From Cornell Forge
Cornell Forge Company is an ISO 9001:2015 certified facility that has been providing forged steel and alloy products for over 90 years. Our family-owned business has earned a reputation as a leader in the forging industry, producing the highest quality hot forged products. With a talented, experienced staff and a commitment to rigorous quality standards, we can help you reduce machining times, waste, and costly production steps. For more information, contact us today, or request a quote to get started.
Forging is a manufacturing process that uses compressive forces to form metal into the desired shapes and sizes. Industry professionals employ a variety of different forging techniques—depending on the material and the product being forged—each of which carries its own advantages and best uses.
The following blog provides an overview of the different types of forging methods available, outlining what they entail, their key advantages, and their typical applications.
Forging operations can be classified into four main types:
Open Die Forging
Open die forging employs the use of two flat or simply shaped dies to apply pressure to the base material from both sides. The application of repeated high-level compression or hammering to the die forms the material into the desired shape. As the dies used do not completely enclose the base material (hence the open die designation) and allow for lateral movement, the process can accommodate the creation of larger and heavier components.
Compared to other forging processes, open die forging produces very little material waste and final products with more consistent grain structures and higher fatigue resistances. The aircraft and railway industries often make use of the process to manufacture large and heavy components, such as cylinders, rollers, and shafts.
Impression Die Forging
Similar to the open die forging method, impression die forging—also known as closed die forging—uses dies to shape material into the desired parts and products. However, unlike open die forging, the dies employed completely enclose the base material. Additionally, in comparison, the process requires much greater compressive forces to ensure the die cavities are fully filled and form the complete part.
Impression die forged parts are typically smaller than open die forged parts. However, they exhibit tighter tolerances (including for near-net shapes) and higher quality surface finishes, both of which contribute to lower production costs for larger production runs due to the reduced need for secondary machining operations. The automotive, mining, and oil and gas industries often rely on the process to produce precision parts such as fittings, flanges, and engine components.
Learn About Our Alloy Forging
While some forging methods require the application of heat to the base metal, there are also a variety of cold forging processes available. Some examples of cold forging methods include bending, cold heading, cold drawing, coining, and extrusion. These processes are used to create a wide range of parts and products in varying designs.
Compared to hot forging techniques, cold forging produces pieces with tight tolerance dimensions and good surface finish quality without the need for heat treatment or more costly materials. The automotive industry commonly uses cold forging to manufacture components with unusual or complex geometries, such as steering and suspension components, braking components, axles, clutches, gears, and pinions.
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Seamless Rolled Ring Forging
Similar to other die forging methods, rolled ring forging compresses dies to shape material. However, rather than using flat dies, the process utilizes curved dies—typically two opposing rollers—to form ring-shaped components.
The rolled ring forging process allows for continuous production, which allows for higher productivity and lower production costs. Additionally, rolled ring forged components exhibit greater lifespans and superior surface finishes than other forged parts. Due to their high durability, they are often used in heavy mining equipment, aerospace engines, wind power generators, and railway equipment.
Get the Expert Help You Need From the Team at Cornell Forge
At Cornell Forge Company, we are pleased to provide some of the highest quality forged components in the industry. With over nine decades of experience, we are well versed in every aspect of metal forging, including closed die forging. For more information on the types of forging available or assistance on an upcoming forge fabrication project, contact us or request a quote today.
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