Open Die Forging Vs. Closed Die Forging

When it comes to metal forging, two primary methods are used to shape pieces: open die forging and closed die forging. At Great Lakes Forge, we specialize in open die metal forging to produce durable, high-quality pieces, including various shapes, discs, stepshafts, and more. In this post, we’ll explore 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 & Closed Die Forgings?

Both open die and closed die forging processes provide various advantages for different applications. Depending on your specific requirements, one method may be more appropriate to achieve the best results for your desired part. Since they consist of different functionalities and physical parameters, open and closed die forging processes are not interchangeable.

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 altered through “hammer” or “stamp” movements until the desired shape is achieved. Advanced open die forging can also produce complex shapes in addition to simpler-shaped parts. Open die forging is often used for forging large or custom-shaped parts, including shafts, cylinders, and discs.

Open Die Forging Advantages

Within the open die forging process, metal parts are heated at temperatures ranging from 1900°F to 2250°F and gradually shaped into the desired configuration through the skillful hammering or pressing of the workpiece. 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

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 forging metal is placed between multiple dies within the open die forging process that do not entirely retain the metal. The dimensions will be changed by hammering and stamping the metal through a series of movements until the final measurements are achieved. Closed die forging is often used for forging smaller, high-volume parts, including connecting rods, gears, and bolts.

Closed Die Forging Advantages

Closed-die forging works with the metal’s internal grain structure and can produce more potent longer-lasting products. 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 and superior mechanical properties
• Reduced or no 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.

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 800-748-0271, and we’ll help you find the best custom forging solutions for your project.

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