Difference between SLA and SLS in Rapid Prototyping
Rapid Prototyping (RP) is a manufacturing technology used by steel fabrication Australia that quickly generates models or parts. There are more than ten different processes, such as stereolithography (SLA), laminated object manufacturing (LOM), selective laser sintering (SLS), fused deposition modelling (FDM), solid ground curing (SGC), three-dimensional printing (3DP_Binder Jetting), ballistic particle manufacturing (BPM), etc. Among them, SLA is the earliest and most widely used technology, accounting for about 70% of all rapid prototyping equipment. This blog will explain the difference between SLA and SLS processes.
SLA – Characteristics and Disadvantages
Stereolithography is the earliest rapid prototyping process, with high maturity and time-tested. The material used is resin and laser of a specific wavelength is used to solidify the resin. The prototype is made directly from the CAD digital model, with fast processing speed, short production cycle, and no need for cutting tools and molds. It can process prototypes and molds with complex structures, and has a strong impact on micro molding. SLA can make CAD digital models intuitive and reduce the cost of error repair. When providing samples for experiments, it can verify and check the results of computer simulation calculations. It can be operated online and remotely controlled, which is conducive to production automation.
SLA has a few disadvantages such as, it is expensive to build, use and maintain. The SLA system is a precision device that operates liquids and has strict requirements on the working environment. Most molded parts are made of resin, which has limited strength, rigidity, and heat resistance, and is not conducive to long-term storage.
SLS – Characteristics and Disadvantages
A variety of materials can be used in SLS. In principle, this method can use any powder material that reduces viscosity when heated, and can produce any shape through materials or various types of coated particles containing binders to meet different needs. Since a variety of materials can be used, the selective laser sintering process can directly produce complex-shaped prototypes, cavity mold three-dimensional components or parts and tools based on designs created using technical drawings. The overhanging layers that appear during the lamination process can be supported directly by the unsintered powder. Since the process does not require a support structure, most of the powders used in the SLS process are relatively cheap, so the cost of the SLS model is relatively low.
It only takes a few hours to dozens of hours from CAD design to the completion of parts processing. The entire production process is digitalized and can be modified and manufactured at any time. This feature makes it particularly suitable for the development of products such as pressure vessels.
The SLS process has some drawbacks. Since the raw material of SLS process are in powder form, the prototype is built by melting the powder layer by layer through heating. Therefore, strictly speaking, the surface quality of the prototype is not good enough as in powder form. Polymer materials or powder particles generally emit odorous gases during laser sintering and melting. Sometimes more complicated auxiliary processes are required. SLS technology varies depending on the materials used, and sometimes more complicated auxiliary processes are required, such as preheating the raw materials for a long time, cleaning the surface powder of the model after the modelling is completed, etc.
The Verdict
Due to the diversity of molding materials, the SLS process is suitable for a wider variety of application fields as compared to SLA, such as prototype design verification, mold master, precision casting investment, casting shell and core, etc. Combined with traditional process methods, SLS can realize functions such as rapid die casting, rapid molding, and small batch manufacturing, injecting new vitality into traditional manufacturing methods. Thus, SLS seems to have the edge over SLA for now!
