When rapid prototyping or even a limited production run is being considered, the choice lies between SLS and SLA. There is frequently a tendency to automatically opt for SLS (Stereo Laser Sintering) in preference to SLA (Stereolithography), though in truth each has its own advantages. This is partially because no support structures are needed. Nonetheless one must look at the characteristics of the various materials available and the end products from each process before deciding.
A major concern is that SLA parts have a better surface finish and are rather more correctly made. This does not indicate that SLS tolerances are sometimes unacceptable: some distance from it. But where appearance and precision are critical (as they frequently are), then this is a vital consideration.
Generally, like with any other engineering material, the choice truly is dependent on the application. This is just good engineering practice, though availability of kit does also play a role in any practical decision. But if a selected process will end in parts which are bound to fail swiftly in use, then an alternative must be sought. The decision should invariably be excusable with hindsight.
Another thing worth considering in any choice between the 2 is the amount of different materials available for each process. The numerous materials all result in different characteristics for the finished product, and this could play as significant a part in whether a part is adequate for its expected job as the procedure. Don't lose touch with the constant enhancements being made in this regard.
A good starting point is to list the minimum requirements for assorted traits before selecting, Sometimes a particular requirement might point in one particular direction or other, or even cross out both processes as being totally unable to supply parts of the mandatory strength. Having such a list enables a reasoned selection of material and process to be made.
While this sounds plain and is less than common sense, masses of engineering is just that: applied commonsense in action. Usually a structured approach leads to better calls. Listing the factors also makes it much simpler to appraise a call after and see what went right (or wrong). If any factor was coincidentally overlooked, then it won't be so easily forgotten for future choices.
Another vital point is whether the part is to be a prototype or be put into production. More tough wants will naturally apply to production parts. The strengths of the two processes are adaptability, speed, and having the ability to work right from a drawing. This implies that if the part is a prototype or will only have a short production run, these processes will have an edge. Longer production runs might easily lean a call in another direction.
Modern production is becoming more flexible thanks to methodologies like SLS and SLA. The integration these strategies offer with CAD design software simplifies matters considerably. This does not necessarily mean they're the sole ones to be thought about for production, though they'll naturally have a massive advantage for three dimensional printing, as this is precisely what they were reserved for.
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