During the process a laser moves along the vat during the epoxy layer by layer. A program instructs the laser based on the 3d cad model loaded into the software.
Once the parts have been completely built they are removed from the tray and placed in a post-curing chamber for final photo-curing.
There are a variety of finishes that can be done to SLA parts. Parts can be sanded, primed, painted, or plated. This requires manual labor as the product that comes out of the machine is not smooth enough.
After 20 years of stereo-lithography being on the market, there is a wide range of materials with varying mechanical properties that allow SLA parts to further try to mimic engineered grade plastics. However, there are still limitation and other processes seem to have left the SLA process behind.
Standard Tolerances for an SLA is: +/- 0.005″ for the first inch, +/- 0.002” on every inch thereafter
Although 3-d printing has become the big buzz over the past few years, the technology is over 30 years old. Given the limitations on quality and speed to make an individual part, 3d printing still lags behind in traditional methods such as injection molding and cnc machining. However, when proving concept and fit with some functionality requirements, 3d printing can be a good choice.
Consider the following chart when deciding which Rapid Manufacturing service is best for your project:
| Process Type | Prototype | Production Parts | Tolerance <.005 in | Quality | Timing | Plastic Material Selection | Price per Piece | Tooling Cost | Tooling Life Expectancy |
|---|---|---|---|---|---|---|---|---|---|
| 3D Printing |
Yes |
Yes
|
Limited
|
Low —
Medium
|
Fastest
|
Limited
|
Mid
|
N/A | N/A |
| Injection Molding |
Yes
|
Yes
|
Yes
|
High
|
Fast — Faster
|
Broad
|
Low
|
Low —
Mid
|
High
|
| CNC Machining |
Yes
|
Yes
|
Yes
|
High
|
Faster
|
Limited
|
High
|
N/A | N/A |
| Cast Urethane |
Yes
|
Yes
|
Limited
|
Medium
|
Faster
|
Limited
|
High
|
Low —
Mid
|
Low
|