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Distinguishing Stretch Forming from Metal Spinning in Metalworking

stretch forming machine

In the realm of metalworking, various techniques are employed to shape metals into desired forms for different applications. Two such techniques, stretch forming and metal spinning, serve as pivotal methods for manipulating metal sheets or components. Understanding the nuanced differences between these approaches is crucial for selecting the most suitable method for specific fabrication needs.

Stretch Forming

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Stretch forming is a metal forming process that involves stretching a metal sheet or extrusion over a form die to achieve the desired shape. This method relies on the application of tensile forces to elongate the material while keeping it in contact with the form:

  • Process: The metal sheet is clamped at its edges and then stretched over a die using mechanical or hydraulic forces. As the material is elongated, it conforms to the shape of the die.
  • Advantages: Stretch forming allows for the creation of complex shapes with precision and consistency, making it ideal for producing curved or contoured components.

What is a stretch forming machine?

stretch forming machine
stretch forming machine

A stretch forming machine is a specialized piece of equipment used in metalworking to form and shape metal sheets or extrusions by stretching the material over a form die or a curved surface. It is particularly effective in producing curved or contoured components with precision and consistency.

The machine typically consists of a frame or bed where the metal workpiece is placed and secured. It includes clamping mechanisms to hold the edges of the metal sheet or extrusion in place during the forming process. The stretch forming machine employs hydraulic or mechanical force to stretch the material, allowing it to conform to the shape of a die or mold.

The forming process involves gradually elongating the metal workpiece over the die using controlled stretching forces. This action causes the material to follow the contours of the die, resulting in the desired curved or shaped component.

Stretch forming machines offer versatility in shaping various materials, such as aluminum, steel, and alloys, into complex and curved profiles. These machines find applications in industries such as aerospace, automotive manufacturing, architectural construction, and marine industries, where curved or contoured metal components are required for specific applications. The precision and repeatability of stretch forming make it a preferred method for creating consistent and high-quality curved parts used in various engineering and design projects.

Comparison of Stretch Forming and Metal Spinning

AspectStretch FormingMetal Spinning
ProcessInvolves stretching a metal sheet or extrusion over a form dieRotating a metal disc or tube against a mandrel
Forming MethodApplies tensile forces to elongate material over a dieApplies compressive forces to shape material
Complexity of ShapesSuited for creating complex shapes and contoursIdeal for producing simpler, symmetrical shapes
Equipment RequirementRequires specialized machinery for stretchingRelatively simpler equipment for spinning
ApplicationsCommonly used for curved or contoured componentsSuitable for producing bowls, cones, and cylinders

Metal Spinning:

Metal spinning, also known as spin forming or spinning, involves rotating a metal disc or tube against a mandrel while shaping it using compressive forces. This method is particularly effective for producing symmetrical shapes:

  • Process: A metal disc or tube is clamped onto a spinning lathe and shaped against a mandrel or form tool as it rotates. The material is gradually formed into the desired shape through pressure and manipulation.
  • Advantages: Metal spinning is adept at creating symmetrical shapes like bowls, cones, and cylinders with smooth surfaces and uniform thickness.

Key Differences:

  1. Forming Method:
    • Stretch forming applies tensile forces to elongate material over a die.
    • Metal spinning utilizes compressive forces to shape material against a mandrel or form tool.
  2. Complexity of Shapes:
    • Stretch forming is ideal for creating complex shapes and contours.
    • Metal spinning is better suited for producing simpler, symmetrical shapes.
  3. Equipment Requirement:
    • Stretch forming typically requires specialized machinery designed for stretching metal sheets or extrusions.
    • Metal spinning can be accomplished with relatively simpler spinning lathes or equipment.


Stretch forming and metal spinning stand as distinct methods in the metalworking industry, each offering unique advantages and catering to specific fabrication needs. While stretch forming excels in creating complex and contoured components with precision, metal spinning is more suitable for producing symmetrical shapes with smooth surfaces. Understanding the differences between these techniques enables manufacturers to choose the most appropriate method based on the desired shape, complexity, and application requirements, ensuring efficient and accurate fabrication of metal components for various industries.