Difference between Open-Die Forging and Closed-Die Forging
Contents
Comparison between Open-Die and Closed-Die Forging
Summary:
Steel could be processed by various forging processes, there are the two most used forging processes are Open-Die Forging and Closed-Die Forging. The major difference between them is forging dies.
Comparison Chart
| Open-die Forging | Closed-die Forging |
|---|---|
| In this method, the workpiece is compressed between the two flat dies. | In this method, the workpiece is compressed between the two impressed dies. |
| The cost of dies is low. | The cost of dies is high. |
| The process is simple. | The process is complex. |
| During the process there is poor utilization of the material. |
During the process, there is better utilization of the material. |
| After the process, machining of components are required. |
After the process, machining of components are not required. |
| The dimensional accuracy of the obtained products is not good. | The dimensional accuracy of the obtained products is good. |
| This process is used for low quantity production. |
This process is used for high quantity production. |
| It is suitable only for the production of simple components. | It is suitable for the production of simple and complex components. |
Open-Die Forging
- It is the simplest and important forging process.
- The shapes generated by this process are simple like shafts, disks, rings, etc.
- An example of open-die forging in the steel industry is the shaping of a large square cast ingot into a round cross-section.
- Open-die forging operations produce rough forms of workpiece hence, subsequent operations are required to refine the parts to final shape.
- Open-die forging process can be depicted by a solid workpiece placed between the two flat dies (lower die is fixed and upper die is moving) and reduced in height by compressing it. This process is called as upsetting or flat-die forging.
Open-Die Forging
- The deformation of the workpiece is shown in Fig. 4.26. Due to the constancy of volume, any reduction in height of the workpiece increases its diameter.
- It is caused by the frictional forces at the die-workpiece interfaces and it can be minimized by using an effective lubricant.
- Some of the important operations performed in the open-die forging process are Fullering, Edging, Cogging.
Closed-Die Forging
- Impression-die or closed-die forging is performed with dies which contain the inverse of the required shape of the component.
- Initially, the cast ingot is placed between the two impressed dies. As the die closes to its final position, flash is formed by the metal.
- This flash flows beyond the die cavity and into the small gap between the die plates.
- The formed flash must be cut away from the final component in a subsequent trimming operation but it performs an important function that, increases the resistance to the deformation of the metal.
- The initial steps in the process are used to redistribute the metal in the work part to achieve a uniform deformation and required metallurgical structure in the subsequent steps.
- The final steps bring the component to its final geometry. Also, when drop forging is used, a number of blows of the hammer may be used for each step.
- As flash is formed during the process, this process is used to produce more complex components by using dies.