Page 61 - Module DMV20173

3.0 SHEET METAL PROCESSES

EXERCISE 4.4

Explain why the drawability of a material is higher in the hydroform process than
in the deep-drawing process?

3.4.3 SUPERPLASTIC FORMING

1. Superplastic alloys can be formed into complex shapes by superplastic forming—
a process that employs common metalworking techniques—as well as by
polymer-processing techniques (such as thermoforming, vacuum forming, and

blow molding.
2. The very high ductility and relatively low strength of superplastic alloys offer the
following advantages:

a. Complex shapes can be formed out of one piece, with fine detail, close
tolerances, and elimination of secondary operations.
b. Weight and material savings can be realized because of the good
formability of the materials.
c. Little or no residual stresses develop in the formed parts.

d. Because of the low strength of the material at forming temperatures, the
tooling can be made of materials that have lower strength than those in
other metalworking processes, hence tooling costs are lower.

1. Diffusion bonding / superplastic forming
1. Fabricating complex sheet-metal structures by combining diffusion
bonding with superplastic forming (SPF/DB) is an important process,
particularly in the aerospace industry.
2. Fig 3.34 shows the types of structures made by diffusion bonding and

superplastic forming of sheet metals. Such structures have a high
stiffness-to-weight ratio.
3. The SPF/DB process improves productivity by eliminating mechanical
fasteners, and it produces parts with good dimensional accuracy and low

residual stresses.

BPLK 93 DMV 20173