SLS and FDM – a comparison

Victoria Malmgren3D-printer, SLS1 Comment


There are different types of 3D printers based on different technologies, but what they have in common is that they fall under the production category of “additive manufacturing”.

Unlike conventional methods, such as milling, sawing, and turning, where a piece of material is machined to remove undesired material, a 3D printer creates a component by adding material in layers. This approach gives makers the freedom to create complex geometries that were previously not possible to manufacture.

Traditional manufacturing methods are, of course, not going away. Instead, 3D printing and additive manufacturing have found a new place in the manufacturing industry. A place where more complex objects like functional prototypes and fixtures for component assembly can be produced. Let’s have a closer look at additive manufacturing, FFF/FDM, and SLS. 

Strong growth and new industries

Powder Bed Fusion is expected to have grown 15,4% each year between 2021- 2025. We will most likely see 3D printers in more industries being used by more professionals. Today, additive manufacturing can be used in the production of spare parts in the industry, as well as for orthoses and other exciting healthcare applications. As more people will use 3D printing technology in the future, it will become increasingly important to know which technology is suitable for which purpose. 

Additive manufacturing techniques are many and varied. There are technologies that use different materials, that are fast to use for different applications, and that can print multiple objects at once. Based on the nature of the object, the cost, and the quality of the object, a comparison can be made between these techniques. 

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Fused Filament Fabrication (FFF) or Fused Deposition Modeling (FDM)

FFF (Fused Filament Fabrication) and FDM (Fused Deposition Modeling) are very similar processes, where FDM is a proprietary technology by Stratasys, Ltd. FFF/FDM based on the printer melting a plastic thread (thermoplastic polymer in filament form) and laying it out in a predetermined path. This process is accomplished one layer at a time until the object is finished. The printing itself takes a few hours, and it usually requires the object to be built with a support structure that is then removed. The finishing process can, therefore, often take a long time. The key is the overall time. 

FFF/FDM-printed objects are not of the same quality as SLS-printed objects in terms of strength and resistance of the object to, for example, UV light, liquids, or electricity. The strongest feature of FDM technology is that it is cost- and time-effective if one wants to make a single item and that there are many different materials available. In addition, FFF printers are sometimes referred to as “desktop printers” because of their small and compact size. Their small footprint can be an advantage in some situations. 

Taken together, all these features mean that FFF/ FDM technology is mainly used for simple prototyping.

FDM Print

Prototype from an FDM 3D printer

Selective Laser Sintering (SLS)

Selective laser sintering (SLS) technology is also based on the layer-on-layer method. The difference is that this technique uses powder instead of wire.  A laser sinters the powder into a predetermined pattern based on a CAD model. Printing with SLS technology usually takes longer than the equivalent FDM technology, but post-processing is faster. 

The main reason for choosing SLS technology is to obtain prints with excellent mechanical performance. An SLS printer can produce very sophisticated objects. It can be a single print that prints all the moving parts – pre-assembled in one piece! – and can also withstand external influences better than an FDM print. SLS 3D printer objects are preferred for end products and functional prototypes. SLS-printed objects are most widely used in the industrial sector. 

Prototype from an SLS 3D printer

The disadvantage of SLS 3D printers can be that they usually require a larger area and more industrial safety and ventilation systems than FDM printers. Wematter has solved this issue by CE-certifying all our equipment, which means they meet the safety standards for household appliances. Powder packaging and powder refill are in a closed ecosystem and the system is plugged into standard 230V sockets and a network connection. 

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About Wematter

Swedish 3D printing company Wematter’s pioneering solution gives hospitals, offices, and workshops access to a comprehensive system. For the first time, employees can easily print components themselves with the same strength and quality as traditional technology. Wematter’s proprietary end-to-end solution enables customers to accelerate product development and in-house volume production. At the same time, the system creates the conditions for increased flexibility, lower risk, and reduced manufacturing and development costs.

One Comment on ““SLS and FDM – a comparison”

  1. Pingback: 5 common myths in SLS 3D printing

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