Open Die vs Closed Die Forging

The process of forging metal has greatly developed over the centuries. From ancient Mesopotamian craftsmen to today’s high-precision automated systems, forging metals has facilitated the growth and development of humanity for over 6000 years.

And throughout forging’s rich and interesting history, two main types of forging have emerged:

  • Open die forging
  • Closed die forging

So what are these two different techniques and what are their applications in the real world?

Here’s everything you need to know about open die and closed die forging:

What exactly is forging?

Before we dive into the details, let’s take a look at what forging actually is.

Forging is the process of manipulating metal via extreme heat (up to 1250 degrees C), compression, and hammering to create new shapes and structures. Various different types of metal are used depending on the desired shape, durability, or function of the final product.

Common metals used for forging are:

  • Carbon Steel
  • Alloy Steel
  • Stainless steel
  • Aluminium
  • Copper
  • Brass
  • Nickel
  • TItanium

Open die forging

Open die forging, involves the hammering of hot metal on an anvil or between two dies that are not enclosed. This allows the metal to be shaped through the process of hammering and compression. As the force is applied to the hot and pliable metal, the metal moves into spaces that are not enclosed until the final shape is achieved. A series of hammer strikes in a certain order and position will achieve certain results, while the shape of the dies also plays a role in determining the final shape and structure of the metal.

Advantages and drawbacks

Open die forging is ideal for certain outcomes and also has some drawbacks compared to other techniques:


  • Better structural integrity and fewer voids or holes
  • Better microstructure
  • Versatile size of working metal shapes
  • Improved grain size
  • Greater strength and durability


  • Lacks intricacy and precision
  • Extra machining is often required to finish off the final product
  • Can lack consistency

Open die forging applications

Open die forging has an extremely high number of applications in the modern world. As the descendant of ancient smith forging, the technique has become highly developed as a technique for producing highly versatile pieces. Open die forging is responsible for the near-net shapes of large components like discs, crankshafts, cylinders, containers, and rings for large-scale equipment powering agriculture, mining and manufacturing industries.

Closed die forging

Closed die forging (also known as impression die forging) involves similar pressure and hammering as open die techniques, however, the dies are fully enclosed – forcing the hot metal into a specific shape. Closed die forging can follow a series of closed die moulds to fine-tune the end result. The desired shape will determine the process from what metals to the number and order of dies used. Both mechanical and hydraulic systems can be used in closed die forging depending on the complexity and scale of the project.

Advantages and drawbacks

Compared to open die forging, closed die impression forging offers a different approach that has some unique pros and cons:


  • Higher accuracy and precision
  • Wastage metal (flash) to increase pressure on the die thus improving the flow of metal into crevices
  • Easier to reproduce like for like models
  • Better finish compared to open die forging methods


  • Small projects and unique moulds can become expensive
  • More costly due to energy needs and setup
  • Some size limitations

Closed die forging applications

Closed die forging is widely used for a variety of different industries that require complex, accurate, and large scale parts. From agriculture, aerospace, automotive, nautical, oil, and gas to military and medical, the application of closed die forging is enormous. Wherever there’s a need for accurate, strong, and durable metal components, closed die forging techniques will play a critical role in delivering those parts.

Open Die vs Closed Die Forging: which is better?

While both open and closed die forging techniques rely on hammering, pressure, and temperature to deform the metal, the two methods are uniquely placed to deliver components with different purposes. Open die forging can quickly deliver on more straightforward projects that require improved structural integrity. Closed die, on the other hand, is better for more complex projects demanding a higher degree of precision and accuracy.

Depending on the component in question, the method and processes involved will also change – often other techniques such as rolling, isothermal, or precision forging methods will be used instead to achieve highly specialised outcomes.

Final thoughts

As two main forging techniques, open and closed die forging are essential to our way of life. They form the building blocks of modern industry, manufacturing and contribute to economic growth and development. Both techniques involve different approaches that have pros and cons depending on the kind of project.

With the stiff competition out there, choosing an Australian forging manufacturer for your fabrication and component needs can prove to be a difficult choice. Get in contact with your local Forging manufacturer for your forging needs. Always make sure they use local materials and have the production capacity to deliver your parts on time and as expected.