SLA Process / SLA Models
Injection Moulding | Vaccum Forming | Selective Laser Sintering | Ultrasonic Welding
The stereolithography process is one of the most widely used rapid prototyping techniques for making plastic SLA models and begins with STL files created from a 3D CAD design. The supports required for overhangs and cavities are automatically made by SLA process software.
The support & SLA model files are cut into thin horizontal slices and sent to a machine which performs the SLA process using a computer controlled laser to draw the bottom layer onto the surface of a liquid polymer that hardens in the places hit by the laser. See the SLA Diagram to the right.
This is lowered to the depth of the next layer which is drawn directly on top of the previous one. This is repeated until the SLA model and stereolithography process are finished. Supports are removed manually once SLA models have been taken from the machine . The slicing method used by the SLA process causes visible layers on SLA models - these are removed by sand blasting.
SLA Process
When considering using the stereolithography process please bear in mind the following :-
1. The accuracy, ± 0.1-0.2% and layer thickness, 0.125-0.2 mm are both dependent on how fast you need SLA models.
2. SLA models created by the stereolithography process are sensitive to UV light.
3. Several, including flexible resins are available - specify if you need SLA models for aesthetics and part evaluation or durability and robustness. Various finishing grades are available, plus painting and texturing e.g. rough spark/high gloss.
4. The SLA process is suitable for creating SLA models with good surfaces and fine detailing which can be used to check 3D CAD models and for limited functional testing e.g. testing the 'fit' in your assembly. For functional models with snap fits, living hinges etc use SLS models.
5. SLA models can also be used to make Polyurethane moulds and 10-20 models vacuum cast from them in resins close to the final moulding material and colour. UL94V0 fire retardant models are also available.
