Request a quote

Forge Innovations

Hot Off The Press

Open Die Forging Process
August 15, 2022

Open Die Forging vs. Closed Die Forging

Finding the right forging method for your metals requires knowing your options. Here is the complete guide on open die forging vs. closed die forging.

As of 2022, the global metal market is worth around $3,949 billion. This makes sense considering the number of applications metal has in our daily lives. Metal is a staple of our existence, from movable bridges to aluminum space equipment to consumer electronics.

Open die vs. closed die forging are two metal forming options for those who want to have custom metal parts manufactured. Here, we will discuss these two metal forming processes and how they impact grain flow and utility. Read on to learn which approach best meets your needs.

What Is Open Die Forging?

Open die forging is a metal forming process that uses multiple dies. None of these dies completely enclose the material as the component is being shaped. Instead, the dies hammer the metal over and over until the forger creates the desired end shape.

Before the process begins, the metal is heated in a furnace. This makes it malleable so that dies can alter its shape.

Hammering and pressing the metal lets you achieve any shape. Assuming that the expert making the material understands metalworking, they will know exactly how to change the billet's dimensions without needing to fully enclose the metal. Open dies are simpler than closed dies because they do not require a specific shape to contain and shape the metal.

Open Die Grain Flow, Benefits and Downsides

The grain flow structure is one of the most significant open die forging benefits. As the metal is worked into the desired shape, grain flow is strengthened as it follows the contour of the piece. The grain flow movement is possible because force is applied to the metal during various forging operations, including upsetting, drawing out and/or rolling.

These methods of forging create a final product that is not porous. In fact, the final product will be stronger and more durable due to its even grain flow and improved microstructure.

Some other open die forging benefits include:

  • Continuous grain flow and finer grain size
  • Consolidation of voids in the material
  • Greater fatigue resistance for long-term use
  • Eliminates shrinkage and similar defects
  • Less material waste (eco-friendly)
  • Better production scheduling as different parts can run through the shop at the same time


There are also a few disadvantages:

  • Usually requires some machining to create the correct dimensions
  • The inability to create shapes with intricate inner passages
  • Rough surface finish (unless refined later)


Open die forging is the most conventional metal forging process available. As a result, despite its shortcomings, it is ideal for R&D, prototypes, oversized components or small-run applications.

How Is Closed Die Forging Different?

Closed die forging is a slightly different process than open die alternatives. It is not a free forging process. Instead, it is often called "impression die forging" because it uses a die impression to give the metal its shape.

Like open die forging, the metal for closed die is heated in a medium frequency induction heating furnace. However, it is then placed in an enclosed die molded in the desired shape of the final product. Then, the metal is compressed and formed into the end product through high pressure or multiple hammer impacts.

Molding dies are made with precision machines before a metal preform is placed between the top and bottom dies. Depending on the component type, machining might not be needed after the end product is removed from the die. This is because the closed die process creates intricate components depending on the detail of the dies.

Closed Die Advantages and Disadvantages

Like open die forging, internal grain flow is formed since material reduction is involved in creating the product.

There are some things closed die forging excels at:

  • A cost-efficiencies are realized with this method for large production runs
  • Little machining is required in most cases (for close tolerances)
  • The ability to create tighter tolerances


Still, other areas are lacking compared to open die forging. These downsides include:

  • High costs are associated with the manufacturing of the dies making this process too expensive for short production runs (since the die production costs are high)
  • The time to produce the dies can push out your deadline
  • Constrained capacity in closed die shops (Once a run is booked, they are locked into that one part until production is complete)


Ultimately, certain applications require closed die forging methods. However, it is less conventional than open die methods.

Which Metal Forging Process Should You Choose?

Open die forging is generally used for products manufactured in small quantities, require large sizes, and are critical for the end user or R&D. Generally, open die forging shapes are easy and used for more straightforward shaped products (rather than complex ones).

Some examples of products made from open die forging include:


These products are often used in shipbuilding, mining, defense and energy industries. However, they are also used in the machines that manufacture semiconductors, food/beverage equipment, industrial machinery, paper and more. Furthermore, with a skilled Forge Development team, like the one at Scot Forge, many complex shapes can be manufactured through the open die forging methods.

On the flip side, the closed-die forging process is generally reserved for creating smaller and more complex products and large production runs.

Some items made by closed die forging techniques include:

  • Forged fittings
  • Lifting hardware
  • Rigging hardware
  • Small/precise car parts
  • Valves


Because of the precision level, closed die forging is essential in industries like commercial aircraft and automotive markets. In general, forgings keep users safe from part malfunction due to the contoured grain flow resulting in higher strength components.

Get Started With Metal Forming Today

While finding the perfect metal piece for your applications can be challenging, it doesn't need to be. Custom forging services can give you tailored parts that meet your precise specifications.

Scot Forge is committed to creating components you can rely on from quality to delivery. Request a quote to learn if forgings fit your project's needs and the best method of manufacture available to you.