Open Forging: Overview, Parts, Working, Advantages, Disadvantages, and Applications

There are various ways to deform a metal; one popular one is forging. It is a process by which the metal is first heated, and then the force is applied either by hammer or machine to give a desired shape. 

Earlier, people applied force on the heated metal by striking a hammer to give a particular shape to the metal. But now, forging has undergone significant changes. Today hammering tools are powered either by electricity or compressed air. The most common materials used in forging are carbon steel, aluminum, and stainless steel.

The forging process aims to create sturdy metal parts, which the casting process cannot do. Whenever the heated metal is applied force, the porosity is eliminated, and continuous grain flow is achieved on the metal, which makes it stronger. Hence it has wide applications.

There are various types of forging, like open die, closed die forging, and many more.

Open die forging or open forging is deforming a metal piece between two dies. The upper and lower dies will not wholly enclose the metal piece.

The article discusses more about open forging in detail. So, you can keep reading this article to know more about open forging parts, working, advantages, and applications.

What Is Open Forging?

Open die forging or open forging is a process in which the metal piece is placed in between the upper and lower die. The two dies are usually flat in shape and do not entirely enclose or cover the metal piece. A hammer applies force to deform the metal.

Hence, the metal piece deforms in any direction except where it contacts the dies. The final or deformed metal pieces obtained by the open forging process are not of accurate dimensions or tolerances. 

Hence they need to undergo machining processes once again. Open die forging is mainly for simple products like discs, cylinders, and shafts. Repeated heating, hammering, and machining improve the metal’s grain structure. So the strength of the metal is increased by undergoing an open forging process.

Parts Of Open Forging

Open forging comprises numerous parts, which are listed below.

1. Hammer

There is a hammer or ram which applies force on the metal sheet. It 

2. Workpiece

It is a metal sheet in which force needs to be applied to deform into a particular shape. The raw metal sheet will undergo an open forging process.

3. Die

There will be two dies in the open forging process. The upper die is attached to the ram or hammer, and the lower die is attached to the anvil.

Working Principle Of Open Forging

Open die forging is an essential process in manufacturing. It helps produce simple and sturdy products, including cylinders, shafts, etc. The working principle of open forging is as follows.

1. Heating 

The metal piece is first heated in a forge or heating furnace. It is usually heated from 500 degrees Fahrenheit to 2400 degrees Fahrenheit. The heating temperature is essential as it will determine the final shape of the material without cracking.

2. Placing

Once the metal reaches the appropriate temperature, it will be placed between the upper and lower dies. 

The upper and lower die in the open forging process is flat and will not cover the metal sheet. Hence its name is open forging. The die is open on the sides, allowing the metal piece to move freely.

3. Hammering 

The upper die is attached to the hammer. The force is applied to the metal piece with the help of a hammer. The metal piece will try to expand in various directions except where it is in contact with the die. 

The skilled worker changes the orientation of the workpiece from time to time to obtain the desired shape.

5. Heating

The workpiece is allowed to cool and then heated again in a forge or furnace. It is again placed between the upper and lower die, and hammering is done. The process continues several times till you obtain your desired product.

Hammering is done on metal sheets numerous times, so there is continuous grain flow in the metal sheet. 

6. Machining 

The open forging process produces parts that are not of proper dimensions. Hence machining process is required to achieve the correct dimensions.

Advantages Of Open Forging 

1. Reduce Material Waste

Open forging involves less material waste compared to machining processes.

2. Customization

Open forging allows you to customize the metal completely. Hence this process is utilized by skilled blacksmiths. They apply their creative knowledge to give a unique shape to the metal.

3. Produce Large Parts

The open forging process can produce large parts weighing 136 metric tonnes.

4. Produces Sturdy Products

The heating and hammering process is repeated in an open forging process, which helps reduce air voids in the metal sheet. It even helps to achieve continuous grain flow and thus increases the product’s strength.

5. Versatility

The open forging process helps to make decorative items and industrial components like shafts and cylinders.

6. Fatigue Resistance

The fatigue resistance of the metal improves through this process.

7. Cost

The open forging process can produce metal components at an extremely low cost compared to other forging processes.

Disadvantages Of Open Forging 

• The products made through open forging are not of accurate dimensions.
• The machining process is required after the open forging process.

Applications Of Open Forging

The applications of open forging are as follows.

• The open forging technique is applied to produce high-quality knives and blades.
• It is widely used in the automotive industry. Open forging helps produce automotive components that need custom shapes and high strength.
• The open forging process helps to produce agricultural components like plowshare.
• The shipbuilding industry utilizes this process to make anchor chains, shackles, and many more products requiring high strength and fatigue resistance.
• Blacksmiths utilize this process to make hand tools like tongs and chisels.
• Handcrafted cutlery like spoons and forks can be made using an open forging process.

What Is Close Forging?

Close forging is similar to the open forging procedure but has a few differences. The metal sheet is first heated until it becomes malleable and then placed between the custom shape dies. 

The dies don’t completely enclose the metal sheet. When the force is applied with the help of a hammer, the metal sheet flows easily and fills the die shape cavities. 

Some excess material flows outside during the process, called a flash. The flash first cools down as it will be in contact with the atmospheric air. But the metal inside the cavity is still hot and soft. The flash will restrict this metal inside the cavity to flow outside. 

As a result, the metal will take the complete shape of the die by remaining inside. The skilled worker will remove the flash in the machining process once the metal cools down completely.

Here almost negligible machining process is required after the procedure. Again the obtained metal will have greater accuracy and high strength after the close forging process.

What is The Difference Between Open And Close Forging?

Open Forging	Close Forging
1. Two flat dies compress the metal	1. Two impressed dies compress the metal.
2. Poor utilization of material.	2. Better utilization of material
3. The metal undergoes a machining process after open forging.	3. The metal undergoes negligible or no machining process after close forging.
4. The dimensional accuracy of the metal obtained after open forging is not good.	4. The dimensional accuracy obtained after close forging is good.
5. It is suitable only for simple components	5. It is suitable for both simple and complex components.
6. Cost of the die is low	6. The cost of die is high
7. The process is used for low-quantity production.	7. The process is used for making large quantity production.

Conclusion

The forging process holds a special place in the manufacturing process. The metal is given the desired shape by heating and applying force. 

Open forging is where the dies are complete, allowing the metal to extend everywhere except where it touches the die. It helps produce sturdy metal parts in aerospace, agriculture, and automobile applications.

We have discussed open forging, the components involved, the working principle, advantages, and the difference between open and close forging. We hope the information is helpful.

Thank you for reading this article.