Stereolothography - SLA

Question 1

Stereolithography - SLA?

Answer 1

Fabricating a solid plastic part out of a photosensitive liquid polymer using a UV laser beam to solidify the polymer.

Question 2

Stereolithography - SLA Category?

Answer 2

VAT Photopolymerisation

Question 3

SLA - Principle/ Method

Answer 3

1 - Scanning the liquid Surface of a Bath of Photo-sensitive polymer resin with an ultraviolet (UV) laser beam that causes the resin to cure in the shape of a layer of the part.

2 - Lowering the platform by the slice thickness after each new layer is formed at the surface.

3 - Final curing cycle in a UV oven to complete photo-polymerisation.

Question 4

SLA - Process Characteristics?

Answer 4

1 - Layer thickness 0.05mm - 0.5mm.

2 - Capable of producing hollow and solid prototypes.

3 - Prototype must start to be built on the tray for support structure.

Question 5

SLA- Surface Finish and accuracy?

Answer 5

1 - Smooth Surface Finish.

2 - Stair stepping and FaceTing depending on layer thickness.

3 - 0.025mm - 0.05mm per 25.4mm of part dimension.

Question 6

SLA - Materials.

Answer 6

1 - Photo-Sensitive polymers (resins)

• Versatile in allowing time mimic a wide variety of engineering plastics (ABS, Polycarbonate)
• Material Spectrum to address requirements such as accuracy, durability and rigidity.

2 - Special application resins

• Resins Filled with non-crystalline nano-particles for improved strength or detail resolution.

Question 7

SLA - Applications?

Answer 7

1 - Functional prototypes, mimic production parts used in functional testing.

2 - Presentation models e.g. design reviews.

3 - Casting pattern for investment casting of metal part.

4 - End use production parts, even assemblies.

5 - Rapid tooling used to create limited-run tooling.

Question 8

SLA - Advantages?

Answer 8

1 - Fast implementation of prototypes in early stages of product development.

2 - Single stage production process produces smooth surfaces even without finishing.

3 - Low material consumption: Non-hardened synthetic resin can be reused.

4 - Multi part assemblies are possible and very high detailed products made.

5 - Cost effective production.

Question 9

SLA - Limitations?

Answer 9

1 - Depending on material, components may be brittle.

2 - Support structures can limit design freedom.

3 - Components are only UV resistent to a limited extent.

Question 10

SLA - Variation?

Answer 10

1) Micro - Stereolithography

• More highly Focused laser (as small as 1um)
• Layer thickness - 10um
• Photopolymers with much lower viscosity to ensure uniform layers.