The Nature of Open Die Forging

Open Die forging: Incremental forging processes for large components

App. An open die forged shaft during heat treatment (Source: Saarschmiede Freiformschmiede)
An open die forged shaft during heat treatment (Source: Saarschmiede Freiformschmiede)

Open die forging includes a number of different forming processes. The shape of the workpiece does not result from the shape of the dies used, but from repeated local forming with geometrically simple dies that are typically moved relative to the workpiece. The shape of the workpiece is created incrementally, i.e. step by step. Usually, this is done when hot forging very large components for the machine and plant building industries, or for the densification of casted ingots. Open die forging is also used where shaping dies cannot be used for economic reasons. For special component shapes, techniques such as rotary swaging processes are used during cold forming of large production volumes.

Open Die Forging: Typical Products and Industries

App. An open die forged shaft, real component. Source: Saarschmiede Freiformschmiede
An open die forged shaft, real component. Source: Saarschmiede Freiformschmiede

Many different open die forging processes are applied in a variety of industries for the production of diverse products. A frequent application is the manufacturing of semi-finished products from casted ingots. Often this centers on the deliberate adjustment of material properties and the densification of pores and blowholes. Another typical application of open die forging is the near net shape manufacturing of large components, such as shafts, crankshafts, disks, rings, shells and containers for the machine and plant building industries. Reactor pressure vessels are a prominent example of sophisticated, safety relevant components made from special materials using open die forging. In the automotive industry, open die forging is used in the manufacturing of (hollow) shafts and other components for engines and powertrains.

Trends and Developments

Where is the development of open die forging heading?

The trend towards ever increasing product diversity and, therefore towards smaller production quantities, combined with an ever decreasing development time, favors open die forging processes as there is no need for the expensive and time consuming manufacturing of shaping dies. Forming simulation favors this trend as it supports the design of open die forging processes, which is often done based on practical experience, and helps to minimize the number of time consuming and expensive test forgings.

The energy efficient manufacturing of semi-finished products and large components is becoming more and more important. It is therefore necessary to minimize the number of heating processes and to use the existing heat where possible so that forging and heat treatment operations are considered holistically. The simulation supports the design of optimized pass schedules and can predict the minimal heating time necessary.

The trend towards lightweight constructions frequently results in the maximum utilization of the load limits of the material and in an increased use of special materials that require sophisticated processing. Especially within the production of semi-finished products, this demands the absolutely flawless, homogenous tuning of the desired properties of the material, while the procedural limits of the material, e.g. the temperature range, must not be exceeded. Within the simulation, the changes in the local material properties during open die forging can be taken into account when designing the process.

Typical Challenges when Open Die Forging

App. Radial forging (Source: SMS Meer)
Radial forging (Source: SMS Meer)

When designing open die forging processes, the pass schedule, including possible intermediate heating, must be planned in such a way as to reach the required final geometry and the required material properties with as little effort as possible. High performance materials such as titanium and nickel based alloys can only be forged within a narrow temperature range.

If your goal is to…

  • Minimize the number of blows, passes and heats?
  • Stay within the “temperature window” for successful forming?
  • Close all pores and blowholes in the cast ingot?
  • Know the resulting material properties prior to the process?
  • Avoid forging errors like fish tail formation?
  • Stay within the load limits of your forging mill?

…then our solution for the simulation of open die forging processes is right for you.

Our Solution for Open Die Forging

App. Control of a cogging press (Source: SMS Meer)
Control of a cogging press (Source: SMS Meer)

The Module Open Die Forging in Simufact Forming

With the Simufact Forming Open Die Forging application module, we offer a software solution that has been optimized for open die forging. Based on application-oriented provided pass schedules, a fully automated closed loop controlled simulation of the process is done for a variety of open die forging variants, including the determination of the necessary number of blows in each pass.

If your process is not covered by the pre-defined variants, it is easy to customize the software so that practically every process with its specific control can be simulated.


App. Open die forging press (Source: SMS Meer)
Open die forging press (Source: SMS Meer)

Use the advantages of Simufact Forming for the simulation of your open die forging processes:

  • Shorter development times with fewer trial runs
  • Comprehensive process understanding
  • High process stability and quality
  • Predictions of component properties
  • Better machine utilization
  • Expansion of the product range
  • Optimum adjustment of the different process stages
  • Higher yield
  • Avoidance of forming errors and cracks
  • Closed-loop process control integrated into the simulation allows the use of production-oriented pass schedules without prior knowledge of the necessary blows,  strokes, and positions


For a functional description of Simufact Forming Open Die Forging, please read our product information:


Simufact Forming Open Die Forging