3D Printing

All 3D printing techniques are based around the same idea. An object is described digitally as a series of layers, the thickness of which depend upon the capabilities of the printing method. The digital representation is used to build up the object in layers. Where physical deposition is employed a cartesian robot is used for the build. The 'print head' is usually index in the x-y plane and the build platform is moved in the z direction. Where laser cure or sintering is employed the xy is often controlled using optical methods and the z is once again controlled by moving the build platform.

Techniques

Stereolithography

The object built up from a liquid (UV cure)
Needs supports for complex shapes, gels often employed

Selective laser sintering

Object built up from a powder (laser)
Does not require supports

Fused deposition modelling

Object built using a fine extruded thread
Needs supports built for complex shapes

Advantages

• Low cost to produce components
• No need to design and make moulds
• Cheap feedstock
• Short time from design to part
• Print derived directly from CAD drawing
• Short design & revision cycle

Disadvantages

• Relatively slow, not as suited to high volume mass production as injection moulding
• Mechanical properties can be less than those found in parts made using other methods of production, in particular the bond between layers is often relatively weak, although this can be mitigated to some extent by careful selection of processing properties.