Week 4: Additive Manufacturing Technologies

Question 1

What is FFF?

Answer 1

Fused Filament Fabrication - an extruder head moves in two directions over a table which is lowered or raised. A filament is extruded through an orifice and complex geometries are created one layer at a time

Question 2

What is SLA?

Answer 2

Stereolithography - a liquid polymer is cured selectively into a solid. A platform is placed in a vat of the polymer and is lowered to create the part layer by layer by the means of an ultraviolet laser.

Question 3

What are SLS and EBM?

Answer 3

Selective Laser Sintering and Electron Beam Melting - non metallic or metallic powder is sintered or melted using a laser (SLS) or an electron beam (EBM) to achieve a desired shape. Build area is being lowered as each next layer is put onto it. SLS is used for plastics and EBM for titanium and cobalt-chrome alloys.

Question 4

What is a composite material?

Answer 4

A composite material is a combination of two or more chemically distinct and insolubale phases with a recognisable interface. The properties abd structural constituents of the composite are superior to those of the constituents acting independently.

Question 5

Describe spray lay up and hand lay up

Answer 5

Open mould processes using a single mould. The materials are placed in proper order (matrix and fibres), brushed and shaped in the mould with a roller. The squeezing action of the roller expels trapped air bubbles and compacts the part. Spray lay up uses - material is sprayed, hand lay up - placed with a brush.

Question 6

Describe filament winding

Answer 6

The resin and the fibres are combined at the time of curing in order to develop a composite structure. Parts are produced on a rotating mandrel. The reinforcing filament, tape, or roving is wrapped continuously around the form. The reinforcements are impregnated by passing them through a polymer bath.