STEREOLITHOGRAPHY (SLA)

About SLA 3D Printing

Stereolithography is a 3D printing technology known for achieving highly detailed and functionally accurate parts. The technology utilizes a mirror that is programmed to direct an ultraviolet laser to draw and cure a part’s cross-section onto a vat of photopolymer resin. After each layer, the build platform lowers and a recoater blade wipes over a new layer of material on the top of the tank. Once the part is complete, it is removed from the build chamber, cleaned of support and excess resin and then placed in a UV oven for further curing. This ensures the part reaches its optimal physical properties.

Sinterize Advantage

At Sinterize, we have wide range of capabilities offerred through single, easy-to-use platform so you spend less time sourcing parts and more time on design innovation.

Overview

Stereolithography (SLA) is an additive manufacturing process that belongs to the Vat Photopolymerization family. In SLA, an object is created by selectively curing a polymer resin layer-by-layer using an ultraviolet (UV) laser beam. The materials used in SLA are photosensitive thermoset polymers that come in a liquid form.

SLA has many common characteristics with Direct Light Processing (DLP), another Vat Photopolymerization 3D printing technology. For simplicity, the two technologies can be treated as equals.

A laser beam is directed in the X-Y axes across the surface of the resin according to the 3D data supplied to the machine (the .stl file), whereby the resin hardens precisely where the laser hits the surface. Once the layer is completed, the platform within the vat drops down by a fraction (in the Z axis) and the subsequent layer is traced out by the laser. The resin that is not touched by the laser remains in the vat and can be reused. This continues until the entire object is completed and the platform can be raised out of the vat for removal.

Support structure is always required in SLA. Support structures are printed in the same material as the part and must be manually removed after printing. The orientation of the part determines the location and amount of support. It is recommended that the part is oriented so that so visually critical surfaces do not come in contact with the support structures

Applications

Master copies for vacuum casting and other low volume prototyping techniques
Patterns for investment casting
Low volume/ limited edition products especially for complex geometries
Dental/ jewelry/ art and other sectors which require high detailing and finish
Visual prototypes for photo shoots and market testing

materials

Clear resin

Color	Property	Tensile Strength(MPa)	HDT
Translucent	Rigid	65	58 °C

ABS like White resin

color	property	Tensile Strength(MPa)	Melting Temperature°C
White	Rigid	60	60

Grey Resin

color	property	Tensile Strength(MPa)	HDT
Grey	Rigid	65	60

Flexible Resin

color	property	Tensile Strength(MPa)	HDT
62.63	65.02	4.28	190 – 220

Castable wax Resin

COLOR	PROPERTY	Tensile Strength (MPA)	Burnout Temperature
Green	Rigid	11.6	249 °C

Design Rules

Minimum Wall thickness: 1.2 mm

Minimum details size: 2 mm (for text/ hole diameters etc)

Layer thickness: 0.1 mm – 0.3 mm

Max dimensions: 650 x 600 x 600 mm. Large parts can be created with assembling individual parts by interlocking designs or glueing together.

Standard Accuracy: ± 0.3% (with lower limit on ± 0.3 mm).

Lead Time: Minimum 2 working days for despatch

Surface finish: visible layers with texture.

post processing

Basic: Support Removal, Curing, Sanding, Smoothing

Add on: Primer, Coating/ Painting

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Frequently Asked Questions

Can SLA Models Be Machined?

Yes, SLA parts can be milled, drilled, tapped or lathed.

Is Stereolithography a faster process than Fused Deposition Modeling?

SLA is slower than FDM because the SLA printer’s laser has a smaller surface area and takes more time to complete each layer. In FDM, the printer can print thicker layers, which results in a reduction of time.

What is the main difference between SLA & DLP ?

SLA uses laser to cure liquid resin where as DLP uses UV light to cure resin.

What is the print resolution in SLA ?

30 to 140 microns

Can we print multi colored part in SLA ?

In SLA multicolor is not possible. We can print multicolor parts in PJP technology.

SLA printed part can be exposed to sunlight ?

Since SLA parts are UV cured photopolymers, they don’t stop reacting to light once fully cured. Over time UV exposure will actually cause the parts to start to break down. This break down can weaken mechanical properties and cause parts to yellow. SLA parts are generally not suitable for environments with extreme daily sun exposure over a period of months or years. A good UV clear coat or paint can limit or prevent this breakdown entirely.

Support marks will be there on SLA printed parts ?

No. If we perfectly do sanding on support surfaces there will be no marks or bumps.

Using glue can we stick SLA printed parts?

Yes, we can stick SLA parts. But not applicable for flexible resins.

What is the minimum accuracy we can achieve in SLA ?

30 microns

Are SLA parts costlier than FDM & SLS ?

Yes, Photocurable resins used in SLA are costly than FDM filaments & SLS powder. But with that extra amount we get superior surface finish in SLA.