Open Die Forging Vs. Closed Die Forging

When it comes to metal forging, the two most common methods are open die forging and closed die forging. While each method offers unique advantages and manufacturing capabilities, choosing the proper method for your project depends on a range of factors, including the complexity of the forged parts, volume, and performance properties.

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At Great Lakes Forge, we specialize in open die metal forging. In this guide, we'll break down the differences between open die forging and closed die forging, including the processes, the outcomes, and the applications that tend to work best for each method.

What is the Difference Between Open Die and Closed Die Forgings?

Open die forging and closed die forging are fundamentally different in how they shape metal, the applications they serve, and the outcomes they achieve. Open and closed die forging processes are not interchangeable since they consist of different functionalities and physical parameters. Key differences between open die forging and closed die forging include:

• Open die forging shapes metal in open space, while closed die forging uses molds under high pressures
• Open die forging can create large parts; closed die forging is best for small parts
• Open die forging can produce parts with custom shapes; closed die forging is limited to the mold's dimensions
• Closed die forging achieves tighter tolerances than open die forging
• Open die forging is more cost-effective for low-volume jobs; closed die forging excels in high-volumes

The Open Die Forging Process

As its name suggests, the open die metal forging process is achieved within a relaxed environment free of encasing devices. The metal workpiece is heated at temperatures ranging from °F to °F and gradually shaped into the desired configuration. It is altered through skillful "hammering" or pressing movements until the desired shape is achieved. Open die forging is often used for forging large or custom-shaped parts, including shafts, cylinders, and blocks. It is also compatible with a wide range of superior-quality materials, including 13-8 stainless steel, carbon steel, and more.

Advantages of Open Die Forging

Some of the most significant benefits associated with open die forging include:

• Improved fatigue resistance
• Continuous grain flow
• Longer part life
• Increased strength
• Less chance of voids
• Finer grain size
• Custom shape design capabilities

The Closed Die Forging Process

Also referred to as impression die forging, closed die forging uses a closed, high-pressure environment to fill an enclosed die. The process involves placing heated metal between two dies, creating a precise impression as the material is pressed into shape. This method is ideal for producing complex parts with consistent dimensions and is commonly used for smaller, high-volume components. Closed die forging excels in applications requiring tight tolerances, precise repeatability, and mass volumes.

Advantages of Closed Die Forging

The benefits associated with closed die forging include:

• Dimensions with tighter tolerances and various shapes can be achieved
• More precise, consistent impressions
• Ability to reproduce nearly any shape or size
• Better surface finish
• Reduced need for additional machining
• Cost-effective for large production runs

Choosing Between Open Die and Closed Die Forging for Your Project Needs

Multiple factors should be considered before deciding which forging method is best for your project, including the part's complexity, the production volume, and the tolerance requirements.

Part Complexity

If the part is relatively simple, open die forging will likely be the more cost-effective method. However, if the part is complex, closed die forging may be necessary to achieve the desired shape and tolerances.

Volume of Production

Closed die forging is generally more efficient for high-volume production runs, while open die forging is usually better suited for lower volume or custom orders. Closed die forging requires more specialized equipment and tooling than open die forging, which can affect cost and lead times.

Tolerance Requirements

Closed die forging typically results in tighter tolerances and a smoother surface finish than open die forging. If your part doesn't require tight tolerances, open die forging is likely the more cost-effective forging method.

Great Lakes Forge is Your Source for Superior-Quality Open Die Forgings

If you need custom open die forgings, Great Lakes Forge is your solution. We specialize in crafting durable, high-performance parts tailored to your exact specifications. Our team combines decades of expertise in open die forging with advanced technology to deliver superior results for even the most demanding applications.

In addition to our forging capabilities, we offer a range of secondary services to ensure your components meet the performance characteristics necessary for your application. Secondary services we offer include:

• Heat treating: Heat treating enhances the material properties of your open die forged parts, including strength, hardness, wear resistance, and more.
• CNC Machining & Milling: We use CNC machining and milling equipment to create components with exceptionally tight tolerances and custom dimensions.
• CNC Turning: Our CNC turning capabilities create precise cylindrical components, including shafts, spindles, and more.
• Fast, On-Time Deliveries: We go the extra mile to ensure you get your custom open die forged components with quick turnaround times.

Contact Great Lakes Forge for Expert Open Die Forging Services

Great Lakes Forge is your trusted provider of open die forging services for metal part manufacturing. Contact us for more information on our custom forging service options, or call us at 800-748-, and we'll help you find the best custom forging solutions for your project.

Are you interested in learning more about Open die forging solution? Contact us today to secure an expert consultation!

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.

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Cold 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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