Open-Die Forging vs. Ring Rolling: Helping You Choose the Optimal Forging Process

In heavy equipment, advanced manufacturing, and the energy industry, the choice of forging process directly impacts both component performance and manufacturing cost. A well-chosen process not only ensures reliable operation under extreme conditions but also significantly reduces maintenance and replacement costs throughout the lifecycle.

This article compares two common ring forging methods—open-die forging and ring rolling—to help you quickly identify the solution that best fits your project needs.

Open-Die Forging: Versatile Shapes, Strength First

Open-die forging is a process in which metal billets are repeatedly pressed and shaped in dies that do not completely enclose the workpiece. It is especially suitable for large, complex structures and components requiring exceptional strength.

Typical product forms:

●Square, round, rectangular, and hexagonal bars

●Solid shafts

●Pressure vessel shells

●Hollow cylinders

Advantages of open-die forging:

●Wide size range: from a few kilograms to hundreds of tons

●Superior strength and density: ideal for critical load-bearing structures

●Flexible customization: accommodates complex geometries and structural optimization

Ring Rolling: Structural Efficiency, Stable Performance

Ring rolling starts with a pierced ring blank, which is heated and then rolled simultaneously in the radial and axial directions. This process enlarges the diameter, reduces the wall thickness, and produces near-net shape components.

Typical application areas:

●Nuclear, hydropower, wind, and refining equipment

●Petrochemical, aerospace, bearing, and gear transmission systems

Key advantages:

Higher strength: continuous grain flow ensures excellent fatigue resistance

Cost efficiency: near-net shapes minimize machining requirements

High reliability: withstands extreme temperatures and pressures

Excellent thermal stability: enhanced load-bearing at high temperatures

Wide material compatibility: applicable to stainless steels, alloy steels, and aerospace alloys

Partner with Iraeta: Simplifying Your Choice

Both open-die forging and ring rolling have their advantages: the former offers flexibility in size and outstanding strength for large, complex custom components, while the latter provides efficiency and stable performance for batch production with high reliability. The challenge lies in finding the optimal balance between performance, cost, and lead time.

Partnering with Iraeta makes the choice easier

Iraeta operates the world’s largest 22,000-ton open-die press and the world’s largest 22-meter ring rolling mill. With these state-of-the-art facilities, Iraeta has built extensive experience and a proven track record in manufacturing large rings and cylindrical forgings.

On the process side, Iraeta adopts the advanced “forge-rolling” method (open-die forging combined with radial-axial rolling), widely used in Europe and the U.S. This process leverages the densification of forging with the precision and dimensional control of rolling. It enables Iraeta to efficiently handle large-diameter, thick-walled rings, cylindrical forgings, and complex geometries—delivering the perfect combination of strength, reliability, and dimensional accuracy.

In solution design, we work closely with customers to tailor the optimal process route based on design parameters, service environments, and performance goals—achieving the best balance of performance, cost, and lead time.