Digital Design Tools (plastics)

Question 1

Rapid prototyping

Answer 1

Making 3D solid objects from a digital file. The object is made using additiv processes, where the object is created by building up successive layers.

Question 2

Methods of digital manufacture

Answer 2

• stereo lithography
• laser sintering
• fused deposition modelling (FDM)
• 3D printing

Question 3

Stereo lithography

Answer 3

The component is built up in layers of liquid photopolymer. When the liquid photopolymer us exposed to ultraviolet light from the laser beam, it cures or solidifies. The platform moves down and the process is repeated

Question 4

Laser sintering

Answer 4

In this process powder is spread over a platform by a roller and then a laser sinters selected areas, which makes the powdered polymer melt and then harden.

Question 5

Fused deposition modelling (FDM)

Answer 5

In this process, a polymer filament is passed through a heating element, melted and extruded. Each slice of the model is drawn from a continuous length of molten filament. Typical build up materials are acrylonitrile-butadiene-styrene (ABS) and polylactic acid (PLA).

Question 6

3D printing

Answer 6

In this process a thin layer of build material, typically plaster or starch based, is gradually glued together by a print head that can also colour the material.

Question 7

Digital technologies

Answer 7

• CAD (computer aided designs)
• CAE (computer aided engineering)
• FEA (finite element analysis)
• virtual modelling
• draft analysis

Question 8

CAD

Answer 8

Used to create and explore ideas through 2D and 3D drawings. The advantages of using CAD are:

• changes can be made quickly
• drawings can be rendered in different colours and materials
• components from built in or online libraries can be used
• designs can be shared electrically

Question 9

CAE

Answer 9

The broad use of computer software to aid design engineers in analysis of tasks.

Question 10

FEA

Answer 10

Allows products to be modelled in a virtual environment and tested for weaknesses such as areas that might need reinforcing with stiffening ribs.

Question 11

Virtual modelling

Answer 11

Used to see how a liquid polymer would flow into and around a mould cavity. Such factors as polymer injection pressure and cooling time can be considered.

Question 12

Draft analysis

Answer 12

Concerned with calculation the optimum draft angle required for a product to be easily released from a mould cavity.