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Reverse Curve Bending of Metal Profile

Reverse curve bending is also known as an S-Curve. In this type of bending, the radius center changes from one side of the part to the other. With reverse curve bending, it’s ideal for there to be a few feet of straight between the two curves, but some steel sections can still be successfully bent without the straight.

In the realm of metal fabrication, various bending techniques are employed to create unique shapes and structures. One such technique is reverse curve bending, which involves the formation of a metal profile with a reverse or inwardly curved shape. This process is often utilized in architectural, decorative, and artistic applications, where distinctive designs and visual impact are desired. In this article, we will explore the process of reverse curve bending, its applications, considerations, and the factors that contribute to successful metal profile bending.

AISC Design Guide 33 Curved Member Design Section 2.2.4

A reverse-compound curve, also known as an S-curve, has two or more arcs in the same plane joined tangentially with reversal of curvature. Completed I-shaped and HSS members with reverse-compound bends, are used in the same applications as compound bends.

To fabricate these members, the member is removed from the machine after the initial bend is completed, turned over, and placed back into the same machine, or a different machine, to complete the second bend. Due to the difficulty in fitting the member into the machine after the first bend is completed, a straight segment between the tangent points of each curve may be required. The minimum straight segment length varies with the member geometry and the bending machine. S-curves can also be formed by bending two straight members and splicing them together at the tangent point.

Understanding Reverse Curve Bending

Reverse curve bending, also known as inward bending, involves the manipulation of a metal profile to create a concave or reverse curve shape. This technique is typically used to achieve decorative and artistic elements in architectural designs, furniture, sculptures, and other metalwork. Reverse curve bending requires precise control of the bending process to ensure the desired curvature is achieved without compromising the structural integrity of the metal profile.

The Process of Reverse Curve Bending

The process of reverse curve bending involves several key steps:

  • Material Selection: The choice of metal is crucial, as different materials have varying properties and behaviors during the bending process. Commonly used metals for reverse curve bending include steel, aluminum, and copper.
  • Design and Planning: The desired curvature and dimensions of the reverse curve are carefully determined during the design and planning phase. Factors such as the radius of the curve, the thickness of the metal profile, and any specific design requirements are considered.
  • Preparing the Metal Profile: The metal profile is prepared for bending by ensuring it is clean, free from imperfections, and appropriately sized for the intended curvature. This may involve cutting, shaping, and deburring the profile as needed.
  • Bending Techniques: Various bending techniques can be employed for reverse curve bending, including manual bending, press bending, and rolling. The specific technique chosen depends on factors such as the complexity of the design, the thickness of the metal, and the equipment available.
  • Precision Bending: Reverse curve bending requires careful manipulation of the metal profile to achieve the desired inward curvature. This is typically achieved by gradually applying force to the profile at specific points or along its length, using specialized tools or machinery.
Reverse Curve Bending of Metal Profile
Reverse Curve Bending of Metal Profile (Aluminum)

Applications of Reverse Curve Bending

Reverse curve bending finds application in a wide range of industries and creative endeavors:

  • Architectural Design: Reverse curve bending adds a unique and eye-catching element to architectural structures, including building facades, handrails, and decorative elements.
  • Furniture and Interior Design: Reverse curve bending is employed in the creation of furniture pieces, such as chairs, tables, and lighting fixtures, to introduce distinctive shapes and visual interest.
  • Art and Sculpture: Artists and sculptors utilize reverse curve bending to bring their creative visions to life. The technique allows for the creation of flowing, organic shapes and intricate details in metal artworks.

Considerations for Successful Reverse Curve Bending

Reverse Curve Bending: 5 Steps, 3 Apps and Considerations
Reverse Curve Bending: 5 Steps, 3 Apps and Considerations

To achieve successful reverse curve bending, certain considerations must be taken into account:

  • Material Properties: The properties of the chosen metal, including its malleability, ductility, and strength, will impact the feasibility and outcome of the reverse curve bending process.
  • Bending Equipment and Techniques: The selection of appropriate bending equipment and techniques is essential to achieve the desired reverse curve shape accurately and efficiently. This may involve utilizing specialized tools, machinery, or partnering with experienced metal fabricators.
  • Precision and Quality Control: Reverse curve bending requires precise control over the bending process to ensure consistent results and maintain the structural integrity of the metal profile. Quality control measures, such as checking for defects, surface imperfections, and dimensional accuracy, should be implemented throughout the bending process.


Reverse curve bending of metal profiles offers a unique and visually captivating element in various creative applications. With careful planning, precise execution, and the selection of suitable materials and bending techniques, metal fabricators can achieve stunning results in architectural designs, furniture, and art. Reverse curve bending allows for the creation of distinctive shapes and curves, adding aesthetic appeal and artistic expression to metalwork projects. By understanding the process and considerations involved in reverse curve bending, designers and fabricators can unlock new possibilities in metal fabrication and unleash their creativity.