What Is Metal Forging?
Metal Forging is the process of shaping a piece of metal using continuous pressure, often used to tool steel or iron. The extreme pressure may require rolling, pressing, or hammering the workpiece to shape it into the desired part. Common examples of forged parts include rolled steel bars and beams.
Press forging is one of the most used processes. Instead of hammering or rolling the material, a press is used to shape the part. To compress the material, the press generates significant force. Some presses may use 50,000 tons of pressure.
After forging the part, the new shape has a denser structure, making it stronger and more resilient. Many types of forging exist. The press forging methods are often categorized based on the temperature at which the parts are forged. The main categories include cold, warm, and hot forging.
Hot Forging vs. Cold Forging
A wide range of metalworking processes is available to forge parts. The type of forging depends on the specifications of the part and the requirements for the production run.
Most metal forging involves the use of extreme heat to soften the metal. With hot forging, the metal may be heated up to 2100 degrees Fahrenheit. As the metal is more pliable, less pressure is needed to form the metal.
After pressing the material, it cools and hardens. The finished part is often much stronger compared to its original form. However, hot forging provides less precise tolerances compared to cold forging.
With cold heading, the metal is not heated. It is formed near room temperature, which makes it better suited for working with softer metals. The main benefits of cold forging include faster production rates and increased interchangeability.
Common Forging Methods
Drop forging is the process of dropping a large hammer onto the heated metal to form it into the shape of a die. Some dies are molds with distinct shapes while others are flat surfaces. The two most used methods of drop forging are open-die forging and closed die forging.
With press forging, a press is used to apply force instead of a hammer. The press travels at a slower speed compared to the hammer, allowing it to reach deeper into the material. The metal workpiece is affected uniformly.
Compared to drop forging, press forging provides many useful benefits. It offers greater accuracy and capacity, making it suitable for large parts. Some presses are automated, which reduces labor and overall costs. It is also a more economical solution for high-volume production runs.
Roll forging is another forging process, mostly used to produce steel bars and long parts. The forging process involves two cylindrical rolls that deform a bar stock. The heated material passes through the cylindrical rolls until the desired shape and size are achieved. This generates less material waste compared to some drop forging methods and allows for favorable grain structure.
Closed Die Forging vs. Open Die Forging
Traditional smith forging is a type of open die forging. This process requires the workpiece to be placed between two surfaces, such as an anvil and a hammer. The hammer strikes the workpiece to form it.
Modern open die forging often involves the use of two dies. The workpiece is sandwiched between the dies but is never fully constrained. Advantages of choosing open die forging include:
- Continuous grain flow
- Reduced chance of defects
- Increased strength and fatigue resistance
- Finer grain structure
Closed die forging (impression forging) compresses the workpiece in a die that contains cavities. The workpiece is constrained in the die. When force is applied, the metal fills the space in the die cavity. As the metal is compressed, excess material is forced out of the die, creating flash. After forging the part, the flash is removed. This method can be used to produce parts weighing up to 25 tons. It also produces near net shapes, limiting the need for finishing.
When Should You Consider Using Metal Forging?
Forging is a vital part of our economy, with parts being forged for use in fields like national defense, automotive manufacturing, mining metals and oil, even surgical and dental instruments can be made of forged metal. Forging has been used for millennia and continues to provide solutions for industries across the globe. Forging may lead to cost savings compared to other metal fabrication processes. These methods are also suitable for use with a variety of materials. However, stainless steel and iron remain the most used materials.
Our Metal Forging Capabilities
At The Federal Group USA, our forging plants are equipped with state-of-the-art presses, including:
- Mechanical press
- Hydraulic press
- Screw press
The mechanical press uses cranks and toggles to create a preset stroke. A mechanical press is faster compared to a hydraulic press, which uses a piston and fluid pressure to generate force. However, the hydraulic press provides greater flexibility and capacity.
These presses allow us to forge weights from two ounces to more than 100 pounds. Our facilities allow us to use a variety of forging methods, including net shape and near net shape forging.
If you’re considering a metal forging project, you may also find our article comparing castings and forgings to be helpful. You can also always contact The Federal Group USA via email or give us a call at (800)759-2658 to get more information about our metal forging capabilities or to request a quote. You can also take a look at some of our previous work in our Forged Parts Gallery