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Stretch Forming vs. Stamping: Understanding the Differences

stretch forming machine

Stretch Forming and Stamping are two metal forming processes that are used to make curved shapes on metal sheets. Although they might appear similar, they have significant differences when it comes to the process, types of shapes that they can create and the materials that they can work with. In this article, we’ll explore the differences between stretch forming and stamping in-depthly.

The Process of Stretch Forming and Stamping

Stretch forming and stamping are often employed in the manufacturing of various industries such as the automotive, aerospace, and architectural industries. Both of these processes are used to create metal parts that can be used for various applications.

Stretch forming, as previously discussed, is a process that involves clamping a metal sheet onto gripper jaws and then stretching it over a die, achieving complex shapes and curves. This process is often accomplished using either a hydraulic or mechanical press.

Stamping, on the other hand, involves a punch and die system to deform the sheet into the desired shape. The punch applies a strong force onto the sheet, while the die supports and guides it, finally achieving the desired shape. The punching power is applied to cut, form, or pierce metal sheets.

Types of Shapes Stretch Forming and Stamping Can Create

Stretch forming and stamping are designed to create curved shapes on metal sheets but have specific types of shapes they can create.

Stretch forming is ideal for creating bends and curves on large metal sheets, whether they are flat or extruded. This stretch forming process can maintain some of the material’s structural integrity by smoothing out any stress risers that may occur from their bending, thus eliminating the need for welding individual pieces into assemblies. Stretch forming can create intricate shapes and curves that are challenging to achieve through other methods, enabling manufacturers to create original high-complexity parts.

Stamping, on the other hand, excels in the production of complex parts with relatively simple shapes uniformly. The process is excellent for standardizing the output and can be used to create high volumes of identical, consistent parts. It can create thin and lightweight cold-formed sheet metal parts, something that can be achieved through deep drawing. The tooling required for stamping is relatively inexpensive than in stretch forming.

Advantages of Stretch Forming and Stamping

Advantages of Stretch Forming

  1. Precision: Stretch forming produces highly accurate and consistent shapes.
  2. Efficiency: Stretch forming can produce complex shapes in a single step, reducing the need for multiple forming operations.
  3. Strength: Stretch forming results in material with higher strength and durability than other forming processes.
  4. Versatility: Stretch forming can create various shapes, including gentle curves, compound curves, and sharp angles, making it an excellent choice for complex geometries.

Advantages of Stamping

  1. Cost-Effective: Die stamping can produce parts in higher volumes at a low unit cost.
  2. Flexibility: Stamping offers a wide range of complex and non-complex shapes.
  3. Precision: It produces tight tolerances with highly precise dimensions.
Stretch Forming Process of Aluminum Alloy Automobile Roof Rack【Stretch Forming Machine】

Top 5 Differences Between Stretch Forming and Stamping

ProcessStretch FormingStamping
Shapes CreatedComplex curves and shapesSimple and complex shapes
ToolingExpensive dies for new geometriesStamp tool is low cost
StrengthHigh strength and durabilityLower strength material
MaterialsMostly used for high-strength materialsWorks well with thinner materials
Process timeLonger process time per partFast process time per part

Top 4 Key Takeaways

  • Stretch forming and stamping are two metal forming processes used to create curved shapes on metal sheets.
  • Stretch forming is ideal for complex shapes like gentle curves, compound curves, and sharp angles on large metal sheets.
  • Stamping excels in the production of complex parts with relatively simple shapes uniformly with tight dimensions and is more cost-effective in producing parts in higher volumes.
  • The differences between these two processes include the shapes they can create, the tooling cost, strength, materials, and process times.

Final Words

Stretch bending and stamping are two different metal forming processes that create unique impressions and shapes on metal sheets. While stretch forming can create complex shapes, stamping can produce consistent parts with precise dimensions, although it requires little investment in tooling. Understanding their differences is essential in identifying the right metal forming process that suits the required applications.