L18 Processing

Name all three forming temperatures and explain their characteristics.

Cold working: at or slightly above room temperature; increases strength through strain hardening. Warm working: between room temperature and recrystallization temperature; offers balance between formability and strength. Hot working: above recrystallization temperature; enables large deformations with low force, no strain hardening.

Name four processes each of bulk working and sheet metal forming

Bulk working: Forging, Rolling, Extrusion, Coining. Sheet metal forming: Bending, Deep Drawing, Stretch Forming, Spinning.

Define the term Extrusion in a forming context. What's the difference between forming extrusion and extrusion for preliminary shaping?

Extrusion is a process in which a workpiece is forced through a die to obtain a desired cross-sectional shape. Forming extrusion involves plastic deformation of solids, while preliminary shaping extrusion may refer to shaping molten material (e.g. plastics) into solid forms.

Name two types of extrusion

Direct (forward) extrusion and Indirect (backward) extrusion.

Give at least two drawbacks of impact extrusion

Requires high pressure and temperature, and leads to inhomogeneous deformation conditions.

Explain the rolling process and name the three most common rolling processes

Rolling reduces thickness or changes cross-section by compressive forces through rotating rolls. Three common types: Longitudinal rolling, Transverse rolling, and Thread rolling.

Describe the term "wiping die bending"

A bending method where a punch forces the sheet metal over the edge of a die using cantilever loading.

How is the defect "Flattening" in tube bending processes prevented?

Flattening is prevented by using internal mandrels or appropriate support tools during bending.

Draw a "first stage" deep drawing process naming the relevant components

The first stage includes: Punch, Blankholder, Die, and Workpiece. The punch pushes the sheet into the die while the blankholder holds the sheet in place.

Give 3 advantages and disadvantages of the deep drawing process

Advantages: Low material consumption, simpler tooling, one-piece construction. Disadvantages: High press setup cost, not efficient for small quantities, high radial and tangential stresses.

Name 5 defects of the deep drawing process

Flange wrinkling, Wall wrinkling, Tearing, Earing, Surface scratches.

Which materials are mostly used in the stretch forming process?

Steel, Nickel, Aluminum, Titanium.

Explain briefly the shot peen forming process and give at least two application of this in the aerospace industry.

Shot peen forming uses small steel shots to plastically deform the surface, inducing compressive stress. Applications: Wing skin forming, Tank bulkheads (e.g., Ariane 5).

How thermoplastic composite materials can be formed? Name the most commonly used forming process.

Thermoplastic composites are formed using heat and pressure; the most common method is thermoforming.

Name 5 common plastics that can be machined with the vacuum forming process.

ABS, PETG, PS, PC, PVC.