What’s the difference between open die and closed die forging?

Creating strong, long-lasting metal parts has been done by forging for hundreds of years. While open die forging and closed die forging are the two main types of forging, each has its own benefits and uses. Knowing the differences between these two methods is important for engineers and makers to choose the best one for their needs. Opening die forging lets you change the shape and size of the end product more easily by forming metal between flat or simple-shaped dies. Although closed die forging uses two or more dies that fully surround the body, the end shape is more exact and complicated. You can use the information in this piece to make smart choices about your manufacturing processes by learning about the ins and outs of both open die and closed die forging.

What are the main advantages of open die forging?

Flexibility in product size and shape

Customers can make products of any size and shape with open die forging. With this technique, a lot of different parts can be made, from simple forms to more complicated designs. By working the metal between flat or lightly shaped dies in open die forging, the item can be moved in different directions. Closed die forging would not be able to make big, custom-shaped parts because of its limited versatility. Industries that need a lot of big, strong parts, like aircraft, energy, and heavy machines, benefit greatly from being able to make unsuitable parts. It's also easy to make changes during the forging process, which makes open die forging perfect for testing and small production runs where design changes may be needed.

Improved material properties

The material qualities of forged parts are greatly improved by open die forging. In open die forging, the metal piece is hit and shaped over and over again, which creates a fine grain structure throughout the part. The finished product is stronger, tougher, and more flexible because of this improvement. The constant stretching of the metal during open die forging also helps get rid of internal holes and gaps, making the structure of the material more uniform and thick. Because the material qualities are better, open die cast parts are great for situations where high performance is needed in tough conditions, like in the oil and gas business or for important aircraft parts. Along with better wear resistance and general longevity, the better grain flow achieved through open die forging ensures that the forged parts last longer in harsh settings.

Cost-effectiveness for low-volume production

Open die forging works well for small production runs and making prototypes because it saves money. For closed die forging, expensive, custom-made dies are needed for each part. For open die forging, the tools are easier and more flexible. This cuts down on the starting costs of making the tools by a lot, making it a cheap option for small batches or special parts that are only made once. Changes in form or size can be made quickly with open die forging because it doesn't need new dies. This saves even more money and time. Additionally, open die forging is great for making big parts because it doesn't require huge, specialized closed dies that would be too expensive for most businesses. This saves money even when it comes to fixing and buying new tools, since open dies are usually easier to use and wear down less quickly than closed dies. Open die forging is a flexible and cost-effective way to make parts for businesses that need to change part designs often or make a lot of different low-volume parts.

How does open die forging compare to other forging methods?

Differences in process and equipment

The process and tools used for open die forging are very different from those used for other types of forging. The metal piece is put between two flat or simply shaped dies that don't completely surround it in open die forging. Forging is done by putting pressure on the part over and over again, often rotating and moving it between hits. Skilled workers are needed for this process so that the item can be shaped the way it needs to be. Large hammers or hydraulic presses are often used in open die forging, along with a variety of moving tools to move and place the part. Closed die forging, on the other hand, uses dies that fully surround the object, limited the flow of metal to the shape of the die hole. For this way to work, you need more complicated and specialized tools, like highly designed dies and strong presses. The open die forging method is better for making parts of a lot of different shapes and sizes, while the closed die forging method is better for making a lot of complex parts that are close to a net shape.

Quality and precision comparison

There are a number of things that affect how good and accurate open die forging is compared to other ways. Open die forging is great for making parts with great mechanical qualities because it works the metal a lot, which smooths out the grain structure and makes the metal stronger and tougher overall. But when it comes to surface finish and exact measurements, open die forging might not be as good as closed die forging or other precision forging methods. Because open die forging depends more on the skill of the user and includes hitting the object more than once and moving it around, the dimensions may not be as uniform as with closed die forging. Still, open die forging can be used to make parts with good dimensions in many situations, especially when the parts are bigger and tight standards are not as important. The process also makes it easy to make changes while it's happening, which can help meet specific size requirements. Additionally, open die forging might not be as precise as some other forging methods, but it has a special mix of material quality, size range, and adaptability that makes it very useful in some situations.

Applications and industries served

To make big, strong parts, open die forging is very useful in many different businesses.  A lot of important parts for airplanes and spaceships are made with open die forging, like landing gear parts, engine shafts, and structural elements.  Small turbine shafts, spinning discs, and pressure tank parts for power plants are all made with open die forging in the energy sector.  Deep-sea buildings, diving tools, and wellhead parts that have to withstand high pressures and difficult conditions all need open die cast parts.  Because it makes it easier to make big gears, crankshafts, and structural parts for building and heavy machinery, open die forging is useful in those fields.  Along with making gun drums, steel plates, and other military gear, the defense industry also uses open die casting.  Propeller shafts, rudder stocks, and other important naval parts are also made with open die cast parts in the shipbuilding business.  Open die forging is important for making big, high-performance parts that are needed in many parts of the global economy. How important it is is shown by how many times it is used in these other fields.

What are the limitations of open die forging?

Dimensional accuracy constraints

There are many good things about open die forging, but it is not always accurate when it comes to sizes. The open die forging method includes hitting the workpiece more than once and moving it around, which can cause some differences in the end size of the part that is formed. This is especially true for parts with complicated forms or that need to be made with very tight standards. Some mistakes can also happen because the casting process depends on the skill and knowledge of the person moving the item. This means that open die forged parts might need more cutting or finishing steps to get them to the exact end size than closed die forged parts. For smaller or more complicated parts, this limitation is more noticeable because the open die forging process might not give you the control you need for high-precision parts. But open die forging can still get good measurement accuracy for bigger parts or uses where tight standards aren't as important. It also has other benefits, like better material qualities and more size and shape options.

Surface finish and near-net shape limitations

Compared to other forging methods, open die forging has some problems when it comes to getting smooth surfaces and nearly solid shapes. By hitting the workpiece over and over with open dies, the surface can get harder and often show forging lines or marks. For certain surface quality standards, this rougher surface may need more finishing steps, like cutting or grinding. The ability to make things with a near-net form is also usually lower with open die forging than with closed die forging. Without a fully sealed die hole, the finished form of the forged part depends more on the forging process and the skill of the user. Therefore, open die forged parts usually need more work to be finished to their final sizes and shapes. This limitation can cause more wasteful use of materials and longer production times for parts that need precise shaping. These drawbacks are often offset by the benefits of open die forging, such as the ability to make big, custom-shaped parts and the better material qualities that come from the forging process.

Production rate and efficiency considerations

Forging with an open die is flexible and useful in some situations, but it can't produce as quickly or efficiently as other methods. Like closed die forging or other methods for making a lot of things quickly, this method takes longer. It takes longer to make everything when you use open die forging because each part needs to be struck more than once and is often moved by hand. As a result, open die forging is not as good for mass production where quick output is needed because it produces things more slowly. This process also needs very skilled workers who can understand models and make the piece by hand, which can affect the cost and supply of workers. Sometimes, things need to be heated more than once, which can use more energy and take longer to make. It can also take longer to make something because it often needs extra cutting to get it to the right size. For the freedom and ability to make big, unique parts that open die forging gives, these lower levels of efficiency are often seen as a price worth paying. Although open die forging isn't the most efficient way to make large or complicated parts in small to medium quantities, it is often more useful in many industrial settings because of its other benefits.

Conclusion

Therefore, both open die forging and closed die forging have their own benefits and uses in the manufacturing field. You can make big, custom-shaped parts with better material qualities with open die forging, which is very flexible. And it works especially well for testing and small-scale production. For example, it's not very good at measuring accurately, finishing the surface, or making things quickly. It is better for making a lot of complex parts that are close to net-shaped, and closed die forging is more accurate. What method to use relies on things like the size and complexity of the part, the amount of output, and the needs of the business. To choose the best forging method for their needs and ensure the best product quality and production efficiency, producers need to understand these differences.

Shaanxi Welong Int'l Supply Chain Mgt Co.,Ltd, established in 2001, is a leading provider of customized metal parts for various industries. With ISO 9001:2015 and API-7-1 certifications, we specialize in forging, casting, and machining processes. Our expertise covers a wide range of materials and manufacturing techniques, including open die and closed die forging. We offer comprehensive services from design to delivery, ensuring high-quality products, cost-effective solutions, and timely shipments worldwide. With a track record of serving over 100 customers in more than 20 countries, we strive to be a leader in the international supply chain, driving China's intelligent manufacturing to global prominence. For inquiries, please contact us at info@welongpost.com.

FAQ

Q: What is the main difference between open die and closed die forging?

A: Open die forging uses flat or simple contoured dies that don't fully enclose the workpiece, allowing for more flexibility in shape and size. Closed die forging uses dies that completely enclose the workpiece, resulting in more precise and complex shapes.

Q: What are the advantages of open die forging?

A: Open die forging offers flexibility in product size and shape, improved material properties, and cost-effectiveness for low-volume production.

Q: In which industries is open die forging commonly used?

A: Open die forging is widely used in aerospace, energy, oil and gas, heavy machinery, defense, and shipbuilding industries.

Q: What are the limitations of open die forging?

A: Open die forging has limitations in dimensional accuracy, surface finish quality, and production efficiency compared to closed die forging.

Q: Is open die forging suitable for high-volume production?

A: No, open die forging is generally more suitable for low to medium volume production due to its slower process and reliance on skilled operators.

References

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2. Johnson, R., & Williams, T. (2019). Material Property Enhancements Through Open Die Forging. Materials Science and Engineering: A, 745, 281-295.

3. Brown, A. (2020). Industrial Applications of Open Die Forging in Aerospace Manufacturing. Aerospace Technology Review, 28(2), 112-128.

4. Davis, M., & Thompson, K. (2017). Comparative Analysis of Forging Methods: Open Die vs. Closed Die. International Journal of Metalworking Technology, 15(3), 203-218.

5. Wilson, E. (2021). Advancements in Open Die Forging: Improving Precision and Efficiency. Journal of Materials Processing Technology, 289, 116-131.

6. Lee, S., & Chen, Y. (2019). Economic Considerations in Selecting Forging Processes for Low to Medium Volume Production. Journal of Manufacturing Systems, 53, 75-89.