What Is SLS 3D Printing & How Does It Work | Difference Between SLS and SLM


There are a lot of commonly used 3D printing techniques, in this article, follow us to understand the SLS 3D printing, what is SLS and how does it work? And SLS vs SLM 3D printing, what’s the difference between them?

What is SLS 3D Printing?

Selective laser sintering (SLS) is an additive manufacturing process in the powder bed fusion series. In SLS 3D printing, the laser selectively sinters the particles of polymer powder, fuses them together, and builds parts layer by layer. The materials used in SLS are granular thermoplastic polymers. SLS 3D printing service is used not only for prototype design of functional polymer components, but also for small-batch production. Its versatility makes SLS an excellent alternative to low volume injection molding.


Can You Use SLS 3D Printing for Rapid Prototyping?

SLS is an excellent solution for functional polymer rapid prototyping because it provides a very high degree of design freedom and high precision. Unlike FDM or SLA 3D printing technology, its parts have good consistent mechanical properties. This means that it can be used to produce parts that are very close to end-use quality, so you can use it throughout the production process, from concepts to test models.


Can You Use SLS 3D Printing for Low Volume Production?

Yes, SLS 3D printing is ideal for low-volume production. And SLS can be used to manufacture parts with complex shapes and geometries, as well as parts with various surface treatments and delivery times.

How Does SLS 3D Printing Work?

SLS 3D printing uses small particles of laser sintered polymer powder. The working principle of this process is as follows:

1. The powder box and the construction area are heated to just below the melting temperature of the polymer.

2. Re coat the blade and apply a thin layer of powder to the construction platform.

3. The CO2 laser then scans the profile of the next layer and selectively sinters the particles of the polymer powder.

4. When one layer is completed, the construction platform moves downward and the blade recoats the surface. Then repeat the process until the whole part is completed.

5. After printing, the part is completely encapsulated in an unsintered powder. Before disassembling parts, the powder box must be cooled, which may take a long time, sometimes up to 12 hours.

6. Clean the parts with compressed air or other sandblasting media and prepare them for use or further post-treatment.

What Is the Difference Between SLS and SLM?

SLS and SLM are both powder printing technologies, which are basically the same in printing process, but they are different in molding principle.



SLS (selective laser sintering) technology uses laser to irradiate the material powder to melt the special added materials to achieve the role of binder, so as to combine the metal powder to achieve metal printing.


SLM (selective laser melting) technology directly heats the metal powder through the laser, so that it can be completely melted in the cooling molding technology.



1. Laser: Although the principles of the two technologies are based on the thermal effect of the laser beam, the SLS and SLM lasers use different lasers due to their different targets. SLS technology is generally applied to CO2 laser with long wavelength (9.2-10.8 μ m). In order to melt metal better, SLM technology needs to use laser beams with high absorption of metal. Therefore, Nd-YAG laser (1.064 μ m) and fiber laser (1.09 μ m) and other shorter wavelength laser beams are generally used.


2. Materials: The materials used in SLS technology need to add a certain proportion of binder powder in addition to the main metal powder. The binder powder is generally metal powder with low melting point or organic resin. SLM technology can completely melt materials, so it generally uses pure metal powder. Since the powder of SLS technology is a mixed powder, even the metal materials with low melting point using metal powder as the binder have low general strength, so the sintered parts of SLS technology have low strength compared with the parts of single metal material. In addition, the SLS sintered parts have voids due to the relationship between processes, and their mechanical properties and forming accuracy are worse than SLM.