Q2 2016 Stereolithography question

Question 1

Fundamental technologies required to establish Stereo-lithography

Answer 1

• high speed computers
• cad, 3d modelling suites
• precise motion control
• uv lasers
• photo-curable polymers

Question 2

Describe how you would build a part from fused deposition modelling for a Referee whistle

Answer 2

• FDM requires support structure so main consideration besides dimensional accuracy is
• minimization of layers (shortens manufacturing time)
• amount of support structure(less material cost, extra time to deposit support structure with dual head, removal of support structure)

-building pea requires a thin support structure to main body of whistle

• orientation needs to be considered in order to produce the part
  1. main internal resonance cavity
  2. open entry for air
  3. open exit for air outlet
  4. outer round shaped body
  5. attachment to build internal ball
  6. lanyard hole

Question 3

Applications in casting industry using different rapid prototyping technlogy

Answer 3

Pattern making

• “quickcast” pattern making using Stereolithography for investment casting
• pattern making for sand/plaster casting

Tool making

• AM technologies use silicone rubbers for mould making used in vacuum casting
• AM technologies use their basic starting material and the mould halves spray painted or plated with a metal coating
• 3D powder printing technology uses a starting material with casting sand like properties and ejects binder to produce mould halves
• 3D powder printing technology uses steel powder and binder to produce a green powder metal part which is subsequently injected with molten bronze, copper, or similar to give it strength.
• Direct metal laser sintering to produce metal mould tooling
• LOM uses sheets of steel or other metal instead of paper.

Question 4

Principle differences between Stereolithography and FDM

Answer 4

Stereolithography

• support structure uses same material as one used to make component
• one laser used to polymerize component structure and support structure

Fused Deposition Modelling

• support structure can be generated from a different material than the one used to make the component, which can be soluble in a solution
• multiple print heads allow different materials to be used

Question 5

Difference between SLS and stereolithography

Answer 5

SLS
-build packet for SLS can be stacked and the entire build chamber can be used as the uncured powder supports the components

Stereolithography

• parts made by stereolithography must originate on the base plate of the build chamber
• parts cannot be stacked due to the liquid resin which in its uncured state cannot be used as support structure